Tree of Water and Power

The following text is a treatise and account of 12 months practical and experimental research and development, in the form of a science and history lesson; it explains and outlines the principles behind the drive to produce TWP, a cost-efficient system and apparatus intended for mass-production and widespread adoption.

Albert Einstein said, “If you can't explain it to a six year old, you don't understand it yourself.” Even so, many technological enterprises are so complex, that nobody is qualified enough to comprehend it. This phenomenon is exploited of course, a story as old as the Emperor’s New Clothes, in which the tailor was paid handsomely. So let’s swallow this pill :) We will try to add a spoonful of sugar to make the medicine go down. Like a tree, there will be some tangents; also like a tree, we will eventually arrive at a point.

Beginning with a light subject.. pun not intended. This joke might make more sense by the end of this section, but since you haven’t got there yet, I will say that light is made of photons and photons are quantum particles, as are electrons. Photons are light, and electrons are ‘electricity,’ and since one of the functions of our apparatus is to generate electric electrical energy from light, the basic principles of this mechanism should be understood.

The word ‘Quantum’ is ubiquitous now in society. It represents the frontier of human understanding, yet we see it used for marketing, techno-bamboozling, even self-help books, and no normal person is expected to understand it. We are not encouraged to understand it, and the language used to describe it is as secretive as the Latin that was once used by doctors to write their prescriptions. Like religion, the new priesthood are the ones reading the scriptures; they are the purveyors of ‘truth.’ With quantum physics, the truth is kept not by priests but by people in lab coats, or professors in university classrooms. Our daily lives have been shaped and influenced by some of these chalk-wielding brainboxes that have explored the mysteries of the same phenomena we are all experience every day and may take for granted; matter, energy, and the patterns of nature.

You might ask if quantum physics is relevant to solar R&D. Quora has answered this question:

Q: “How useful is quantum mechanics in solar energy”
A: “For a theoretical understanding of how photovoltaics work, having some understanding of quantum mechanics is absolutely central to getting anything done, such as computing the theoretical efficiency of a given cell for a given light spectrum. It’s a 100% quantum effect.”

By the end of this section, you will understand what quantum physics is (which may not be quite the same as ‘understanding quantum physics’); why it is called quantum physics, and what makes it different to regular physics. There will be no math and there won’t be a test at the end of this. It’s a complex subject as evidenced by Richard Feynman’s description - “There was a time when the newspapers said that only twelve men understood the theory of relativity. ... On the other hand, I think I can safely say that nobody understands quantum mechanics.” Feynman was a professor at Caltech here in Pasadena, and won the Nobel prize for his contributions to Quantum Electrodynamics (the interaction of light and matter).

Interesting loosely related fact: It can take a photon millions of years and longer to reach us from across the galaxy. The light we see may have been emitted before the dinosaurs existed. However, since time passes more quickly the faster we travel, and a photon travels the speed of light, a journey that seems like millions of years for us, seems like only a moment to the photon. In that sense, photons do not experience time. That’s relativity.

Dictionary definition of quantum: a discrete quantity of energy or any physical quantity.

So, ‘quantum’ as a word can be described as a fixed irreducible single unit of something. It can’t become smaller than it is, and it can only get larger by adding multiples of itself. Like Lego. It’s an absolutely fixed unit.

Atoms are made up of protons, electrons and also neutrons. If an atom was the size of a cathedral, the particles wouldn’t even be the size of flies, yes these particles move so vigorously that they would have the properties of a cathedral in terms of ‘volume’ - not because the particles are solid, but because they generate magnetic fields, the same magnetic fields we are familiar with in iron magnets, only the distance is different.

Electrons are considered elementary particles; they are indivisible, and nobody truly knows what they are. Protons and Neutrons on the other hand, can be further subdivided (by smashing them using particle accelerators) into quarks; nobody know what they are either. Electrons whiz, vibrate, or ‘appear’ (in two places at the same time, like photons), around the nucleus of an atom, (at approximately 1% the speed of light in a hydrogen atom, but are capable of moving at almost the speed of light) while the electron itself is also spinning. Einstein published a paper describing electrons as singularities, or in other words, ‘little black holes’ whereby electrons and black holes could be described in the same way, mathematically. There are many that reject this premise, but their reasoning is as unsatisfying as the premise itself is inspiring.

Hydrogen is the simplest atom; it is the lightest element, and the first element in the universe to be formed before all the heavier elements were fused from hydrogen in the furnaces of stars. A hydrogen atom consists only of a single proton and a single electron. The electron in this atom is the same as all electrons everywhere - they're all identical. If you remove the proton from this same hydrogen atom, it will be the same as any other proton in any other atom. All electrons and protons are the same. All the elements heavier than hydrogen on the periodic table were made with the building blocks of hydrogen electrons and protons.

Newton gave us the rules of physics that are accurate enough to get to the moon, launch satellites, and space probes. It seems like everything we can see and touch adheres to these rules so faithfully that they would seem like the be-all and end-all of physics. Except it has its limits, and not just when it comes to ‘non-newtonian’ fluids. Without a little help from Einstein’s relativity, GPS satellites would be out of synchronization, as their velocity actually means they experience time at a different rate to the ground.

We are used to various rules which seem to be incontrovertible in the physics we deal with every day - gravity; momentum; friction; thermodynamics; acceleration; volume; mass; density; temperature; pressure and many other constants. They are reliable too. Hold your hand out, release an apple, and it will fall down to the ground. It will not float into space. Now do it a thousand times and see how reliably it does this every time. Heat water to make a coffee, and it always boils. Every time. No two ‘objects’ are ever the same; snowflakes, fingerprints, DNA, even twins; they’re always slightly different, whereas quantum particles of the same type are identical.

The rules change for the molecules, the atoms, the electrons, protons and neutrons. Everything else above these particles in scale is divisible but these particles are not (yes, protons and neutrons can be divided into quarks but they would cease to be protons and neutrons). Photons are also indivisible and identical to one another (although their energy level and wavelength can change, which correspond to both amplitutude and where they fall on the electromagnetic spectrum). Photons and electrons interact; photons can excite electrons to a higher ‘orbit’ which is the principle driving photovoltaic applications and excited electrons can emit photons, which the principle driving electroluminescent applications. It works backwards too; high-energy gamma radiation (photons) can be used to make electrons, though we will not be doing that experiment. On a fundamental and pragmatic level, matter and energy are interchangeable. You might even think of matter as ‘captured light’ or as Yoda said, “Luminous beings are we. Not this crude matter.”

These indivisible quantum particles are not governed by the classic laws of physics: gravity; momentum; friction; thermodynamics; acceleration; volume; mass; density; temperature; or pressure; they are not even 100% reliable; sometimes the proverbial pot boils, sometimes it doesn't. When you shine photons though glass, a certain amount of these photons will go through the glass, and some will be reflected back. Do we know which photons will pass through and which will be reflected? No - we must use probability to predict the behavior of large numbers of these particles. Unlike releasing an object with our hand, and watching it fall to Earth, which we expect to occur 100% of the time, with quantum mechanics there is uncertainty. All the rules of classic physics do not apply, there is an entirely different set of rules which must be learned. These rules can be pretty crazy and unintuitive; as Richard Feynman said, “Nothing you’ve experienced can prepare you for this.” The kookiest quantum behaviors and theories boggle the mind. Electrons can even become entangled when you bring them close together, and then when you separate them by any distance, like psychic twins, the one shares the other’s feelings; excite one electron, and the other gets excited at the exact same time, and the signal between the electrons travels faster than the speed of light; it’s instantaneous. This is quantum entanglement.

Linus Pauling was a professor at Caltech, in Pasadena, 1927–1963. He was a top-drawer smarty-pants; ranked as the 16th most important scientist in history, author of “chemistry's most influential book of this century and its effective bible,” The Nature of the Chemical Bond; and the only person ever to win two unshared Nobel prizes. Pauling pioneered and co-founded the field of quantum chemistry, which is the quantum mechanics of chemical reactions. Angela Merkel, PM of Germany, has a PhD in quantum chemistry. On a related side-note, Merkel has shut down several of Germany’s oldest nuclear power plants offline, and plans to permanently close all of them by 2022, with complete dependence on renewables. Her qualifications make these actions all the more interesting.

We established that electrons are in all matter, and that electromagnetic radiation (light, infrared, ultraviolet, radio, x-rays etc) is made of photons. You could say that photons and electrons are the most mobile and active of these quantum particles. Photons whiz around through vacuums and matter at the speed of light (and experience no time) and in our world, electrons usually orbit an oppositely charge nucleus, though with some encouragement they will travel along a copper wire, though actually quite slowly (as slow as 1mm/second) however the signal is transmitted at practically the speed of light (much like a quantum Pez dispenser) or faster even. The fact that the electrons travel so slowly (along a wire) but provide so much energy shows you just much power is ‘in’ them.

Electrons are negative in charge, and protons are positively charged, so it would be intuitive to think they are counterparts, but they are not. Protons have far less mobility than electrons, and in fact, electrons already have an equal and opposite counterpart - the electron hole. It is what is sounds like, it is the absence of an electron, but somewhat confusingly, this counts as a ‘positively charged particle’ or ‘quasiparticle’ and is the meaning of the plus-sign on any battery you might see. The negative symbol is for the electrons.

Electrons are the driving force in all chemical reactions, bonds and physical properties. Electron states dictate colors, flavors, friction, magnetism, even water surface tension. Besides the obvious electronics, motors, and communications devices; adhesive tape, soap, cooking, organic life-cycles, everything that involves the properties or behaviors of matter. According to wikipedia, oxidation (whether it is an apple cut open, or iron rusting) is described simply as, ‘the loss of electrons.’ Vitamin C is an antioxidant, and it does this by donating electrons. Electricity is essentially the movement of electrons; therefore vitamin C is electricity; you can taste the electrons, mmm. Interesting fact, Linus Pauling encouraged Richard Feynman to consume vitamin C for his health later in life. Pauling was a well-known advocate of vitamin C, an obsession that might have been hard to understand otherwise without knowing the quantum mechanics behind it all. An interesting side note to further demonstrate that electrons play a part in everything including biology; the blue dye ‘Methylene blue’ is used as an “alternative electron acceptor” to treat methemoglobinemia and other more exotic conditions. Prussian blue dye is used to treat thallium and cesium poisoning (both radioactive), although it’s not entirely clear whether either works as an electron receiver or donator. Literature tends to play it safe and suggest that it “plays a part in the transfer of electrons.” Since the first atomic explosions in 1945, every living thing on the planet contains cesium 137; the next time you see someone chugging a blue gatorade or necking blue M&Ms, they might not seem as crazy. The fact that substances’ color can be indicative of their electron state and therefore function, is notable, but not constant; zinc oxide and white lead are both white, but one of them is a food additive and the other is poison.

Linus Pauling created the periodic table of electronegativity which is still used today. All the elements on the periodic table have varying abilities, or tendencies to either donate or receive electrons. This phenomenon is utilized in diodes. Diodes are more interesting than they sound; lasers are diodes, solar panels are diodes, televisions are diodes, light emitting diodes are diodes. It might be worth knowing what a diode is. The most common type of diode is a semiconductor that creates a bias for the flow of electrons in a particular direction. This semiconductor is most often made of a single ceramic, but which has been doped with different impurities on each end, or side, of the diode. One half, or part, is doped to be biased towards electron-donation (n-type), the other is doped for electron-receiving (p-type). A silicon solar panel is made of two flat surfaces of silicon, the upper half and the lower half being doped with different impurities. When photons excite the free electrons that exist between the boundary between these two differently doped semiconductors, they are compelled to travel along the electron gradient created by the imbalance at the interface between the two semiconductors.

Devices that utilize the programmability of materials by combining semiconductors of varying properties, including electronegativity, are able to perform various and countless functions without any moving parts - they are solid-state. A simple example of a solid-state would be a security light with a motion sensor; a more complex example would be a modern television (unless you count buttons), a touchscreen smartphone, or a solar panel. Most technology seems to evolve towards the solid-state version of itself, since the introduction of the transistor. A transistor is a semiconductor which acts as a switch, with no moving parts. This allowed for the miniaturization of electronics and the microchip revolution. Computers have always essentially been machines with countless switches, either switched on or off, 1 or 0. With enough switches, highly complex functions can be performed. The switches are more clearly visibly in the first computer, Charles Babbage’s Analytical Engine. An interesting side-note; Ada Lovelace, the daughter of poet Lord Byron, was the first person to write an algorithm for Babbage’s machine, which makes her the first ever computer programmer.

In the transistor, those same ‘switches’ did not require moving parts; they could switch on and off very, very quickly; be vastly more numerous, and extremely tiny.

Vinyl-cut stencil for electron-collecting electrode

Tiny Distances and Surface States

Since electrons are responsible for the bonds between atoms and molecules, most of the electrons in an ‘object’ are occupied and unavailable, holding onto other atoms. If there are a surplus of electrons, or electron holes, we can say that the material is ‘charged.’ An atom or molecule with a net negative or positive charge is called an ion. Anions are negatively charged, cations are positive.

In a negatively or positively charged object, these surplus electrons or electron holes, gather on the outside of the object. There, they are available, to either migrate to another object, or travel through, or more accurately, across, its own surface. When electricity travels ‘through’ a metal wire, the electrons are actually traveling on the surface of the wire, between the metal and the insulation (if there is one).

It is possible to make a material which is mostly only ‘exterior’ surface area, and not much else, such as a single molecule layer of graphene. These single-molecule-thick materials are often called 2-dimensional materials and are readily available. When graphene is a single molecule thick, it becomes an unparalleled superconductor. In this quantum world, tinier can be better; much like an Edison lightbulb glows brighter when the filament is thinner. In a silicon solar cell, all the electrons are being excited at the interface between the differently doped semiconductors, and not inside the materials themselves; it could be inconceivably thin and it would still function as well, as long as the interface between the two materials was the same. The only functional part of the solar panel is actually, literally, 2-dimensional, and even a moderately thin solar panel, is either mostly wasted, or support material so the cell doesn’t collapse under its own weight.

Electrons are very, very small things. By their nature they are smaller than atoms, because atoms are made of electrons and not the other way around, and atoms are still very small things themselves. We know that an object’s ‘surplus’ and ‘available’ electrons hang out on the surface, where they seek balance by being attracted to oppositely ‘charged’ materials and being repelled by similarly charged ones. We can demonstrate this practically by rubbing a balloon on our heads; or placing a comb next to lightly flowing water, to see this magnetic effect at a distance. Water is positively charged, and is attracted to the electrons (which are negative in charge) that collect on the increased surface area of the comb. You can also observe where there is no attraction between materials, like water rolling off teflon. Both are positively charged, and do not attract, they repel. This allows increased surface tension of the water, which is the point in scale where the behavior of water can be observed as being more strongly affected by quantum effects than by Newton’s laws of physics. This is also the case with capillary action which is caused by adhesion, and adhesion is a result of the quantum effects of electron interactions. Interestingly, adhesion, officially at least, remains a mystery. That’s right, nobody really know why things stick to each other. The best we have are ‘theories of adhesion’; no less than five different forces are considered to be significant but so far there is no consensus as to how much of the consequence is due to which force. It’s good to remember that we don’t and can’t know everything; far from being limiting, this reminds us that there is potential for improvement in almost all things.

These tiny electrons can be stored, or gathered for later use, but you can’t put them in your pocket and not in a plastic bag, and you can’t hold them in your hand. Well you can, but all the electrons on your hand are otherwise occupied. Storing electrons (and electron holes) is only useful if you are able to retrieve them for later use, when you want to charge your phone or switch on your flashlight (forgetting for a moment that batteries exist and that they are an abstract concept that doesn’t help us understand how electrons are stored). Since electrons are so tiny, they need tiny spaces to store them. They can actually be stored using an empty space, or gap, between two conducting surfaces; the electrons aren't stored in the gap; the electrons and electrons holes gather in ‘numbers’ on either side of this gap, or empty space, but they never touch. This gap needs to be very small, because electrons are small, and they must be close to each other to be able for their forces to interact (without touching). It is these gathered electrons and electrons holes which can be recalled for later use.

When there is an increase in numbers of electrons and holes on both sides of the gap between the conducting contacts, we are building up a ‘charge’ ie. charging the battery, or charging a capacitor. Often, a ‘spacer’ is used to maintain, or enhance the effect of, this gap, especially by using a dielectric material instead of simply air, paper, plastic, glass or ceramic.

This is the concept of a capacitor. If you look at the symbol for capacitors, it looks like a gap between two plates. A capacitor stores electrical charge for later use, in innumerable devices we use every day. Capacitors are recognizable as one of the more important and mass-produced components in electronic circuitry, but the story of the capacitor is also the story of the battery too.

The first ever electrical battery capable of producing a continuous current was made by Italian physicist Alessandro Volta in 1799; his battery consisted of many alternating zinc and metal discs stacked on top of each other with tiny gaps between them, using brine-soaked cardboard or felt spacers to maintain the gap distance.

The first use of the term battery is credited to Benjamin Franklin in 1748, as published in an 1767 account titled, “History and Present Status of Electricity.” by Joseph Priestly, inventer of soda water, and discoverer of oxygen (or dephlogisticated air as he called it). Franklin and Priestly were both members of the UK’s Lunar Society and were in frequent correspondence. Franklin placed multiple ‘Leyden Jars’ in series to increase their power, calling them a ‘battery’ comparing them with a ‘battery of cannons.’ The Leyden Jar was invented in 1745 by German cleric Ewald Georg von Kleist, because he thought electricity might be a liquid, and so he attempted to ‘bottle’ it. And it worked like a treat, even if the reasoning was unsound. The Leyden Jar is filled with water or other fluid, and a metal rod is is part submerged in the build and part extending out the neck of the bottle. On some versions the inside and outside is lined with foil. It would later be discovered that the electrical charges were building up not within the fluid, but on the surface of the glass.

These Leyden Jars could be made to spin cylinders using static electricity and perhaps some other experiments, but mostly people were impressed by how they could be electrically shocked when they touched it. Electricity was still a mysterious force and there were no applications for it yet. The jars supposedly generated up to 60,000 volts in short bursts, which meant eventually people stopped wanting to touch them. Imagine being Benjamin Franklin’s houseguest in the age of parlor tricks. “Hey, come here and hold this..”

Many electrical engineers are not aware of what a capacitor, or a resistor, or a diode, is made of, or how they work; they only know their function as part of an overall circuit design. There’s no shame in this; a mechanic knows how to put a car together but they may not know how to make the parts. No one person can know everything; it takes a world full of specialists to create the magic of our modern day experience. For our purposes we must demystify this subject because it is important for our story.

Ceramics are what these components like this are most often made of. What’s a ceramic? According to wikipedia, it’s a “solid material comprising an inorganic compound of metal or metalloid and non-metal with ionic or covalent bonds...” Thanks wikipedia, that sounds cool and might make sense if you’re a brainiac, but not helping to clarify things so much. The dictionary definition of ceramics is even worse: “made of clay and hardened by heat” and the dictionary definition of ‘clay’ is a “stiff, sticky fine-grained earth, typically yellow, red, or bluish-gray in color and often forming an impermeable layer in the soil. It can be molded when wet, and is dried and baked to make bricks, pottery, and... ceramics.” And, we come full circle; according to the dictionary, ceramics are made of clay, and clay makes ceramics. Any more questions?

Let’s start with clay, which we’ll call by its longer name, Aluminum Silicate Hydroxide. You’ll notice that it has aluminum in the name, which is metal; it has some silicate, which is silicon and oxygen; silicon being a metalloid, which means it has ‘metal-ish’ qualities. It’s also got the word hydroxide at the end, which is oxygen and hydrogen. Since it has ‘oxide’ at the end, we also know it’s lost some electrons along the way.

More simply, we can say that many or most ceramics are metal oxides. Glass is made of silicon dioxide, and shares some physical qualities and processing technique with ceramics. Silicon is used as a semiconductor for microchips, and silicon is a ceramic, according to wikipedia’s snappy definition of it. Other ceramics, which are also metal oxides, are also semiconductors, such as titanium dioxide and zinc oxide. These particular ‘electro ceramics’ are of interest to us because they have some unusual properties. As metals they were once conductive, but as oxides, they are semi-conductive. Not all oxides are semiconductors, aluminum oxide for example is an insulator, even though aluminum is a great conductor. Besides titanium dioxide and zinc oxide being ceramics and semiconductors, they are something else entirely: they are regular white pigments.

The history of pigments is very interesting indeed, yet in some ways it is a short story. Stable pigments are not that common in nature; when they are found they are appropriately treasured and have been prized since antiquity. From familiar pigment sources like indigo to more unexpected sources such as seashells, insects, and mummified remains; everything at hand has been tried. However industries require steady and reliable sources for pigments on a large scale, and there are surprisingly few pigments to choose from. Most colors can be obtained by mixing a few key primary pigments.

Let’s take the history of white pigments. At first we had chalk, like cavemen. This is calcium carbonate, and it’s still used today on blackboards. Then we had lead white which was used for thousands of years before the dangers became apparent. Lead white was replaced by zinc oxide, and zinc oxide was replaced by titanium dioxide. Those are the only four choices for white pigment and all of them are derved from metals; two of them are metal oxides, the other two are metal carbonates, and carbonates contain hydrogen, oxygen, and carbon.

If you’re looking at something right now that is white, perhaps a mug or something made of plastic, then it almost certainly contains titanium dioxide. It’s in ceramics, plastic, food, toothpaste; whatever is white, that we wish to remain white ie. a stable pigment. Zinc oxide is also in food, cosmetics, and is an active UV-blocking ingredient in sunscreen, and the main ingredient of calamine lotion. It really gets everywhere :-) Most of these pigments are used for ink and paint, worldwide.

At the risk of sounding like an informercial, that’s not all! Titanium Dioxide and Zinc Oxide have some amazing qualities besides being white-colored semiconductors. They are also photocatalytic. A catalyst is something that facilitates a chemical reaction without being consumed; a photocatalyst facilitates a chemical reaction in the presence of light. In fact, the phenomenon of photocatalysis was discovered first in titanium dioxide, and its ability to split water molecules into oxygen and hydrogen in the presence of sunlight. Titanium Dioxide is also used as a photocatalytic antibacterial coating on some hospital equipment (thin enough to be invisible and not white-colored); when it is exposed to light, specifically UV, the photons excite the electrons in the titanium dioxide into a more excited orbit, and they electrocute the germs and mold on the surface. It can also be applied as a thin transparent layer to make self-cleaning windows, by breaking up organic matter with its electrical charge when exposed to UV. You can see the electrons in titanium dioxide (almost any white object) become excited and emit photons when it is exposed to a UV blacklight - they fluoresce.

Zinc Oxide is also a photocatalyst, but it is also piezoelectric which means it produces an electric charge when it experiences mechanical stress (when it is bent); and it is also pyroelectric, which means that it produces an electric charge when it experiences changes in temperature. Interestingly, bones are also both piezoelectric and pyroelectric too. Since Titanium Dioxide is photocatalytic, and zinc oxide is piezoelectric and pyroelectric, it’s difficult to know how much charge is generated by which material in our prototypes, when they are both part of the same device, since the overall effect is cumulative and synergistic.

PVDF, or polyvinylidene difluoride, is a polymer which is used widely for its piezoelectric and pyroelectric properties. They are used in solid-state weighing scales (since pressure changes its resistance it can be used to measure weight) and is also used as a binder for electrodes for lithium-ion batteries. We have used both PVDF and zinc oxide successfully for a dye-sensitized solar cell (DSSC) and an all-inorganic perovskite solar cell. Even though PVDF is a polymer, it comes in fine powder form, and is extremely printable as a pigment

Titanium Dioxide and Zinc Oxide are catalytic ingredients in both these types of solar cell (DSSCs and PVSCs), but they are just a piece of the jigsaw. By themselves they would not come close to being competitively efficient in terms of generating an electrical charge. As for the remaining ingredients there are multiple schools of thought when it comes to increasing the efficiency of the cell overall:

The name says it all, it’s sensitized with dye. But why? Intuitively it would seem that black materials would absorb more light and white materials would reflect more light, and there is some truth to this, but it’s not the whole story. Black materials can absorb visible light and emit infrared; infrared radiation from the black material appear might appear invisible or ‘black’ to us, but it would appear white if we saw infrared light. On top of this, infrared radiation is better at carrying heat energy than other (visible) parts of the electromagnetic spectrum, so a black material can experience heat energy loss faster. Better absorbers are also better radiators.

Colors reflected that are on the visible spectrum are a clear indication that visible light is being absorbed and not re-emitted or reflected. It helps to think about what makes any material a particular color. We established that color is dictated by electron states. If a material is red, it’s not just because it reflects red light (it does do this, but white materials also reflect red light, along with green and blue together, which makes it white). A red material reflects red light but also absorbs blue light and green light, which leaves only red light reflected. Instead of reflecting the blue and green light, these blue and green photons are absorbed by the electrons, which excites the electrons into a higher and more excited orbit around the nucleus. If the electrons get excited enough, they can move along a circuit like an electron pez-conga-line, with a little encouragement from some appropriately doped semiconductors (including titanium dioxide and zinc oxide) controlling the direction of electron flow. Using different metals with different work functions for the electrodes (one biased for electron donating, and the other one biased for electron receiving) further encourages electron flow in the desired direction, increasing the current.

Our DSSC utilizes 3 different dyes mixed together; phthalocyanine blue, phthalocyanine green and rhodamine 6G red. All these dyes emit light under UV radiation demonstrating their sensitivity to photons, and when combined together they appear dark grey, but under UV light they emit red, green and blue light to make an attractive white light. That’s not useful in itself but it is a very unusual property to see in action. The dyes are organic, which means they are based on a carbon molecule, and are therefore readily synthesized and available. That’s all organic means; it doesn’t mean it’s safe to eat. In fact inorganic materials can be safer, it’s case by case. These dyes are exceptionally stable. Phthalocyanines are used for car paints, and Rhodamine G is used for tracking river systems and in dye-lasers.

DSSCs are technically less efficient than silicon solar cells at peak power but have the potential to generate more energy overall because they do not have a cut-off point; they are able to generate electrical current in lower light levels, even from artificial light sources, when silicone cells would stop working completely.

Perovskite solar cells emerged from the development of dye-sensitized solar cells. It is natural to assume that it is the natural replacement, however both fields are so young that there is no single authority on the subject. The materials in a PVSC are all layered and differently doped inorganic semiconductors sandwiched between two conducting electrodes of different materials, much like a DSSC. It is similar to a DSSC, but it doesn’t use dye as a photon absorber, it uses perovskites.

Perovskite, a little confusingly, is the name of a mineral, calcium titanate, but also the name of any material with the same crystal structure (the arrangement of the atoms) as calcium titanate. These materials are typically metal oxides, semiconductors and ceramics, and some naturally occurring mineral compounds.

Like the word ‘quantum’ there is a reasonable amount of hype around perovskites. There is a lot of press saying that lead is a critical ingredient to achieve maximum efficiency but that’s not unanimous. The highest performing prototype PVSC currently has lead in it, but the slight increase in performance is far outweighed by the potential liabilities of manufacturing massive volumes of lead-containing product.

It’s entirely possible to add one type of cell to another and increase the efficiency of the combined cells. The effect is cumulative, the output is not limited to a device’s lowest performing element, as you would think intuitively. The highest performing solar cells in the world are perovskite solar cells attached to conventional silicon solar cells. Hybrids are a good thing. The same happens with dog and animal breeding strangely, the phenomenon is called ‘hybrid vigor.’ or ‘heterosis.’ The interface between two layers of differently doped semiconductors (where all the action happens, as we established earlier) is called a ‘heterojunction.’

There is a great deal of flexibility in the architecture of the cell; it comes down to convenience and value - more important than technical efficiency over surface area is the resulting cost per kilowatt hour; the only technical measurement of consequence.

There are only so many ways to make artificial light. It was a big accomplishment when we did it the first time with fire, and we tend to make a big deal every time we come up with a new way of doing it, and rightfully so. It’s dark half the time, and light is more important than just being able to read a book at night. Light is security in the darkness; it is refuge; it is a hallmark of civilization. After fire came the electric lightbulb of course; Thomas Edison was not the first apparently; there were supposedly 22 people before him that also made lightbulbs. However he did do it best, which is why we associate him with the lightbulb exclusively. There are dozens of variations on this same lightbulb design, and then there are few alternative such as fluorescent lamps :-( and of course we now have pleasant LEDs. Electroluminescent (EL) cells are, by the strictest definition, LEDs (light emitting diodes) because they are diodes, and they emit light. However the term is used to describe a different kind of design. LEDs are small and very bright. EL lighting is any size, flat, and lower in the brightness density as a result. It’s functionality as lamp is improved with surface area. If EL lamps had the same light density as LEDs, they would be blinding. A common example of an EL lamp would be an exit sign in an office or hotel which remains on constantly thanks to its reliability and low power requirements, and of course the instrument panel in your car.

EL lighting architecture is extremely similar to solar cells of all kinds, as well as capacitors; they are thin, wide and flat devices. The electrodes are flat and on the top and the bottom like bread in a sandwich; the active materials are the filling in between them. In fact, an EL light is technically already a capacitor and a diode; they were born to be combined in some way it seems.

EL lamps are slightly different to solar cells in that they do not require electrons to flow through the circuit. They require the phosphor layer’s electrons to be excited momentarily (by bashing them through a kind of membrane that is the capacitor gap), before being allowed to collapse back on themselves into their original orbit. When the electrons collapse, they emit a flash of light, then they stop. EL lamps require high voltages with low currents (low power overall) alternating current only (AC) at a high frequency, to create as many flashes over time as possible to create a continuous light. The EL lamps in digital watches had tiny transformers in them to output 600 volts from their batteries. A stun gun is able to produce 100k volts from a 9V battery; the current is reduced accordingly. It is still enough to create a much larger electric ‘arc’ because of the high voltage. Also, a stun gun hurts more when you touch it, than a 9V battery :-) All EL lamps require a small transformer or dedicated power supply to function. These can be powered by 9 volt or AA batteries, or for a large number of EL lamps, a neon-light power supply would perform the same function with more power.

Phosphors are a group of materials that emit photons when their electrons are excited by an increased electric charge, or if another electron from an outside source collides with it, or passes through it. An electron gun in a cathode ray tube television (CRT) works this way. In a CRT the electron gun fires electrons straight towards the viewers’ eyeballs and brain, but on the way to their destination, they excite the electrons within the phosphors that are embedded in the television screen, creating pretty pictures to distract us while electrons turn our brains to jelly. Phosphors still exist in modern flat televisions and telephone screens and any kind of digital display. There are no phosphors that emit white light; they generally emit a narrow spectrum (a single color) and multiple types of phosphor with multiple types of dopants to achieve a full spectrum white. Phosphors are made of ‘transition metals’ which includes some metal oxides. Metal-doped Zinc sulfide is the classic electroluminescent phosphor. They all have their various and characteristic colors which can be mixed together to provide the desired hue. The recipe for the phosphors in old black & white televisions, is zinc sulfide and yttrium oxide doped with silver, aluminum and copper. After 70 years of the technology, may of the recipes are now known, but the EL industry is not forthcoming with their application techniques and trade secrets, understandably. However this means the entire field of EL is still shrouded in mystery and there is not even a consensus on exactly why the mechanism behind electroluminescence works, and not much on how.

The oldest known metal casting in history is a copper frog, 3200 BC, cast in Mesopotamia. China has been casting since at least 1300 BC. India since 500 AD. Since none of us were there, these dates might be completely inaccurate, but we can at least establish that humanity has been casting for a long time; longer than we’ve been counting to ten (earliest evidence of decimal system is 3100 BC, in Egypt, whereas Mesopotamians had a base 60 system, circa 3400). Again, I wasn’t there, but that’s the consensus.

In that time, we’ve had ample opportunity to establish techniques and methods for best practice. There are multiple variations of metal casting, but they are similar in the sense that it involves pouring molten metal into a fire-and-heat-proof mold, such as sand or clay or both mixed together.

The casting process involves making patterns. Patterns are a ‘positive’ (not a ‘negative’ like photograph film) of the final shape; that is, it resembles the final piece being cast. Each cast object requires at least two patterns, one for each side of the object. Those patterns of both sides of the object are used to make an impression into a sand/clay mixture and then removed, leaving a negative impression in the sand (which contains some clay). Those two ‘sides’ are put ogether to make a single mold which molten metal is poured into. The sand mold can then be broken apart leaving a single piece of cast metal, which then has to be finished and polished. If the cast metal is to have a hollow core, a negative pattern of the hollow core must be made to create a positive cast of the core made of sand, and this sand (clay helps it stay together) core is then placed inside the main negative sand cast before molten metal is poured into it.

Once the patterns exist, they become templates that can be used to cast items ad infinitum.

3D printers that remind me of a Spinning Jenny. My daughter calls them, technically correctly, the ‘robots’

In order to make an impression into sand for sand-casting, that very first pattern has to be sculpted. The pattern is made traditionally by hand-carving a hard but workable material, such as wood. By the nature of the process, this first stage takes time, but castings from the pattern can be made quickly and are mass-producible.

Wood is traditionally used to make patterns, but plastic can also be used, specifically in our case, 3D printed parts. TWP has ten branch connector patterns (20 halves), each with several critical dimensions; it would require several hundreds, possibly thousands of hours of skilled labor to hand-sculpt and finish. 3D printed parts are faster, more accurate, and dimensionally consistent.

3D printing is only decades old but has quickly matured to a point where the benefits are undeniable; it has permitted previously unobtainable or unrealizable concepts to be manifestable, and quickly. It allows for countless iterations of prototypes that would otherwise be impossible due to cost and time restraints.

Machined aluminum connectors

The Renaissance’s Printing Press

Johannes Gutenberg invented the printing press in 1440. The emergence of this technology at once meant that all accounts after that point became more reliable and indelible; it was practically the beginning of crystallization of records. If only a single book in an entire print run survives time, the matter of record is preserved. It can be reproduced and shared again, ad infinitum. It is not only of benefit to the fidelity of the information, but it is of benefit to all people that would now have access to the body of humanity’s experience, simply because of high volume production capabilities and subsequent low cost. Most of the information in this body of text is available because it was printed at some point in history.

It’s difficult to fully appreciate the impact of the printing press on humanity’s quest for knowledge and understanding, unless we imagine what it would be like without it. Before the printing press, knowledge was hand-written, and unreproducible without writing it again for each subsequent copy; greater amounts of information meant the greater the obstacle to its reproduction and therefore propagation.

For instance, ‘Journey to the West’ is a 16th century Chinese novel written by Wu Cheng'en. The story is about a Buddhist monk named Tripitaka who is instructed to make a pilgrimage to obtain the Buddhist scriptures from India. It is a fantastic story full of magic and monsters, but is inspired by real life events about a Chinese monk in the 7th century who travelled to India to obtain better translations of Buddhist scriptures. The Buddhist scriptures are called ‘The Tripitaka’ and the body of work is so large, it takes several years to read from beginning to end, let alone translate. (it’s not even completely translated into English yet). Now imagine there are no photocopiers, and you have to not only read it, understand it, and translate it, but also write it all down again. Then you have to carry it back to China on horseback. The real Buddhist priest spent 13 years on his pilgrimage. To say that information was previously more costly and harder to obtain, would be a massive understatement. Before the printing press, handwritten and illustrated books containing some of the secrets of the universe must have been more valuable than gold, jewels, or even palaces. They were hand-painted by artisans with rare pigments, adorned with jewels, and had gilded pages; they must have seemed magical and precious beyond riches.

According to National Geographic, the printing press is the most important invention in history, so, well done, overachieving Johannes Gutenberg; although National Geographic would say that; they are a printed magazine after all. Also, according to National Geographic, the lightbulb is the second most important invention in history. Interestingly, we are combining the two; we are producing a light source that can be made with a printing press.

The pigments which were mentioned earlier; which are also ceramics; which are also electroceramics; which are also semiconductors; which are also pigments used in wall paint, oil paints, plastics, dish ware, make-up, and food etc. are the exact same pigments used the different printing industries; it is only the type of solvent and viscosity that vary. This means that besides being able to print images and words, print presses are capable of producing intelligent and solid-state functional devices without any retooling or special equipment; all the engineering is executed via circuit design and material/pigment design.

Sik-screening station

Silk Screen Printing Prototypes

Since all pigments are the same in all inks and paints, the testing method for print functionality does not have to be the same as that used for manufacturing. That is, it is impossible to efficiently make a single print on an offset printing press; it can take hundreds of sheets in order to ’make ready’ the press so that it will print correctly. That would mean 100s:1 wastage for every single iteration. Silk screen printing is a process whereby it is efficient to make a single print at a time, necessary when making repeated iterations for experimentation for R&D.

Although the Chinese have been silk screen printing for a thousand years, it has only been popular in the west for about a hundred years, since the introduction of light-sensitive emulsions; one could say it took a remarkably long time to become popular.

Prototype electroluminescent cell

Salt Batteries and Supercapacitors

As mentioned previously, the first ever battery was the voltaic pile, made by Alessandro Volta in 1799, and that this battery is technically a capacitor. Before Volta, it was Luigi Galvani in 1780 that first discovered the electrical phenomenon that led to the voltaic pile. He found that if he put two different metals together, one made of copper, the other zinc (what we would now call electrodes, with different work functions) and then placed those metals onto the leg of a frog, that the frog’s leg would move. He called it animal electricity. A charge was built up on the metal rods, and they discharged into the frog’s leg causing the muscles to contract. In fact the phenomenon requires an electrolyte to be present, which is contained within the frog’s leg; they are the same electrolytes we have in our body: sodium, potassium, calcium, bicarbonate, magnesium, chloride and phosphate.

Alessandro Volta developed this idea and responded with the voltaic pile, a non-biological battery made of alternating zinc and copper discs interleaved with paper soaked in saltwater (which is an electrolyte solution). His accomplishment was achieving this without the use of a frog in any way. In an example of an early energy arms race, Luigi Galvani believed that electricity was a phenomenon exclusive to living (or previously living) organisms, and responded by making a 100% biological battery, made from a number of dead frogs in series. Volta won that race, as evidenced by the fact that we do not insert frogs into our remote controls and our smoke alarms; nor do we all live in a frog-matrix-like world that provides for all our energy needs.

One of the common denominators in Volta’s voltaic pile and Galvani’s frog battery, is the electrolyte. Batteries require electrolytes, and have done since the very first frog battery. Salts dissolved in a fluid eg. water or blood, makes an electrolyte solution. Sodium is a volatile and unstable metal until it teams up with chloride, iodide or a sulfate, and then becomes a ‘salt’; likewise with calcium, magnesium and potassium. Lithium, sodium and potassium are alkaline; potassium is the alkaline referred to in ‘alkaline batteries.’ The lithium manganese oxide in lithium batteries, is technically a salt; salts comprise of cations and anions; lithium is the cation and oxide is the anion. Many lithium salts are used as medications, including lithium carbonate, lithium acetate, lithium sulfate, lithium citrate, lithium orotate, and lithium gluconate.

Interesting fact about lithium: along with boron (an essential ingredient for life on Earth) and beryllium, lithium cannot be made inside stars, because these elements are intermediate steps in other fusion reactions; they are the only elements that get ‘skipped.’ Only after the stars explode, and the heavier elements are then exposed to the intense radiation of a black hole or neutron star, can these remaining elements be created. It’s a long and winding road to get to where we are.

In the interest of clarity, we should establish the difference between batteries and capacitors... zzz... sorry but it is an important distinction, albeit with little visible consequence to the consumer; they both provide power on demand, they just do it in different ways, which results in different behaviors. Ultimately, in terms of language, anything that provides electrical power will be referred to by people as a ‘battery’ even if this is not technically accurate. So, here we go, hold on tight for this next part, we’re almost finished..

A circuit with a capacitor actually has a gap in the circuit; a tiny gap, as we've covered, where opposite charges (electrons and electron holes) can build up on either side of this gap. No charged particles actually cross this gap, so there is not a flow of electrons or holes, they merely build up at these contact plates, and when they are discharged, they leave the way they came. Imagine a rubber membrane in a water pipe. You can force water into the pipe, and that water will exert pressure on the membrane, allowing force to pass through the membrane, but not allowing water to pass through it (electrons in our case). The membrane is under tension, so when pressure on the water is released, the stored energy in the rubber membrane pushes the water back out the way it came in. This is actually an established analogy of what happens with electrons and holes on both sides of this ‘gap.’ In reality this gap can be the gaps within a porous material, such as carbon, or the gap between two strips of foil rolled up with some paper in between, or a miniature maze-like network where the two contact plates run parallel to each other to obtain the maximum surface are possible. Surface area can be increased as much as 100,000 fold, just by using a textured surface rather than a smooth one.

In contrast there is no gap in the circuit with a chemical battery. The electrical circuit, ie. the pathway for electrons and electron holes, is unhindered; the circuit passes though the electrolyte, which is usually liquid or liquid-like, like saltwater. The electrical ‘charge’ is contained and transmitted within this electrolyte matrix. The electrolyte contains both positively and negatively charged particles (ions) which attract and transport both electrons and electron holes; like tiny magnets in which opposite poles attract.

The practical difference is that capacitors can charge almost instantly, and discharge completely just as instantly. This is actually quite desirable, but in some ways, less efficient than a chemical battery. There are hybrids being developed, and there are some that believe that the future lies in extremely high surface area supercapacitors that can charge in an instant, but will discharge slowly and steadily. Much like the various photovoltaic cells, there are multiple methods to store an electric charge once you understand the mechanism. (Insert frog joke.)

Prototype electroluminescent cell

Solid-state Electrolytes

Car batteries have liquid electrolytes, and cannot be turned upside down otherwise they leak. Alkaline batteries are called dry cells because they don’t have a liquid electrolyte, but they still use a pastes or gels which arguably are not that dry, and still have the potential to explode if the battery is overcharged, discharged or heated.

In both Alessandro Volta’s voltaic pile battery, and Luigi Galvani’s frog battery, the electrolyte is liquid, or at least moist, or soggy. This is still the case, and modern batteries require a sealed enclosure to contain these wet electrolytes, or they would quickly dry out and cease to function.

Alessandro Volta experimented with his own pile battery in which the salt water had dried up, and noticed that it still kind of worked, but it was Johann Wilhelm Ritter was the first to publish, in an “albeit obscure journal” (thanks again, Johannes Gutenberg) the phenomenon of the ‘dry’ battery pile in 1802, three years after Volta invented the pile. Ten years after that in 1812, Giuseppe Zamboni invented the ‘Zamboni pile’ which was designed to be a dry battery based on Johann Wilhelm Ritter and others’ observations. However, it did utilize honey. Is that cheating a little? It’s true that honey does not dry out nearly as fast as water, but it’s still wet, or at least I wouldn’t exactly call it dry, or solid. (Honey is reputed to un-spoilable; 3000 year-old honey in the Egyptian pyramids was apparently still “perfectly edible”) The somewhat-dry Zamboni was capable of producing a high voltage, but a low current. It turns out that a less ‘mobile’ electrolyte reduced the current, but not the voltage; a Zamboni pile is still capable of producing thousands of volts, and they were still being manufactured until about 30 years ago for specialized and military applications. A pair of Zamboni batteries power the “Oxford Electric Bell” which has been ringing continuously since 1840; it is the Guinness World Recorder as "the world's most durable battery.”

There are several salt-themed batteries being developed; sodium batteries, salt water batteries, molten salt batteries and more. I say salt-themed, because all batteries would seem to require some kind of salt, of which there are many different kinds to choose from. Salt is defined as a compound (a combination of elements) with equal or “related numbers” of anions and cations (negatively and positively charged atoms or molecules). Salts that we use in our bodies are sodium chloride, potassium iodide etc, as we have covered. Just sodium by itself isn’t technically ‘salt,’ chemically speaking (pure sodium is a metal that combusts when exposed to air). Salts are crystalline compounds when they’re dry, but when dissolved in a medium, these anions and cations ‘disassociate’ freeing them to hold a ‘charge’ from other sources, and an allows an electric current to flow within the medium. If a salt solution dries up, the salt recrystallizes as the anions and cations re-attract and hold onto one another; at this point they are not available to perform the same function as when they are dissolved and separate. It’s worth noting that the elements that make up a ‘salt’ are on the opposite ends of Linus Pauling’s electronegativity scale, so they’re really attracted to each other as a compound, when they’re not dissolved in a fluid. In theory if sodium was separated from sodium chloride, it would burst into flames in contact with water.

The entire field of solid-state electrolytes (SSE) as far as I can observe, is disparate and divided. It’s not exactly a glamorous subject, not like quantum physics or rocket science; it is a blindspot of sorts. SSEs have been described as the “holy grail” for battery development, even though technically speaking, the second battery ever invented uses an SSE and has been operating without interruption since 1840. There are numerous parties that have produced, or are developing SSEs. IBM is developing a solid-state ‘quantum’ battery “made from materials that can be extracted from the sea, which outperforms today’s technology across the board,” This could be a word for word description of what we have achieved so far with our prototype; our functional solid-state electrolytes are also obtainable from the ocean; sodium iodide and potassium iodide, which are both used as medicine.

There are few incentives for the big battery producers to change their existing business model, since the battery market as it currently exists is thriving. I’m not suggesting any kind of conspiracy, it’s just that a change of state requires inducement, for either humans or electrons.

TWP Anodized Aluminum Components

TWP Research and Development

Congratulations, the science and history lecture is over, you got to the end of it. Now let’s try to have a Mr. Miyagi ‘Wax-on, wax-off’ moment. The following should make much more sense to you than if you skipped everything up until this point.

As of May 2020, we have designed and built the following:

• Functional prototype for a printable DSSC (dye-sensitized solar cell)
(that also converts UV into full spectrum visible white light)
• Functional prototype printable PVSC (perovskite solar cell)
(Both DSSC and PVSC are also piezoelectric and pyroelectric)
• Functional prototype for a printable EL cell (electroluminescent cell)
• Functional prototype for a printable, solid-state electrolyte*
• All TWP’s 3D printed tree branch connector patterns
• Combined DSSC with solid-state electrolyte**

**We have produced a functional prototype of a pigment-printable, dye-sensitized cell which is at the same time, a photovoltaic, piezoelectric, and pyroelectric, self-charging, solid-state battery. *The electrolyte is a combination of sodium iodide and potassium iodide dissolved into a water-based flexible resin polymer commonly used as a pigment binder for printing onto fabrics. Solid electrolytes of this nature are called ‘fast ion conductors.’ We measure a 0.6V open circuit voltage from an area the size of a large stamp.

Only half the cells electroluminesce on the prototypes: The functionality and uniformity of the electroluminescent layer is sensitive to 1/1000th of an inch. Any variation in thickness, gap, or piercing of the layers during fabrication, can be critical. The next stage of prototype needs to be made on a small-scale printing-press; however before this can be done multiple iterations were by hand (just as any large-scale print-job requires a ‘proof’ before printing high volumes) with the expectation that not all the cells will function, exactly because they are made by hand and not a machine; it is next to possible to flawlessly reproduce the effect of a camera, photocopier or printing press with a paint brush. However these early-stage prototypes demonstrate proof of concept, enough to begin printing on a scaled-down lithography press, using the same techniques exactly as traditional large-scale lithography presses. The prototypes demonstrate that when the cell design and circuit is applied uniformly, and without errors (much like an impression by a printing press) there is functionality.

Other points worth noting:

• The EL cell is rated for greater power; at low light/power levels like we're using to test prototypes, the light is blue, but appears white with greater brightness/more power.

• LIke a neon light, EL requires a transformer to convert low voltage DC into high voltage, high frequency AC. The power source we are using for hand-made prototypes with uninsulated circuits is a 9V battery, for safety.

• The EL cell, the solid-state electrolyte cell, and solar cell, all utilize the same circuit; only the materials are different. The circuit design is a template for countless apllcations that require increased surface area.

• The solid-electrolyte cell and the DSSC utilize graphite, which is the traditional material for electrodes in some batteries. When graphite is subjected to sufficient shear forces (such as a blender) graphene is produced. In fact the graphene that won the Nobel Prize was harvested from graphite using scotch tape. When graphite is blended and distributed uniformly within a medium with sufficient viscosity at proportions that yied the optimum percolation level, a graphene network within the medium can be created. Independently, the terms ‘graphene’ and ‘perovskite’ are used heavily as marketing tools by battery and solar cell developers.

12 months of research and development has been conducted by myself, and co-funded by Kevin Davis who works at a famous space agency here in Pasadena, and is the drill-operator for a rover currently on Mars.

Implementation

The next stage for TWP is to build a showcase demonstrating both the mounting structure and the energy cells in combination. Prototype construction of the mounting system is complete, patent application has been filed.

— Michael Simon Toon