At New Scientist Live 2018 Dr. Jess Wade gave a fascinating talk on the future of plastic electronics, showing a deep passion for the topic and detailing just how interesting plastics in the manufacture of electronics can be. The talk detailed the production, development, construction, and technology behind various types of polymer-based goods.
Smart Tech has come a long way in just a handful of years, developing from heavy cumbersome devices barely capable of making a phone call to 3-D printed flexible circuits built into polymer patches for application to a variety of surfaces. Smart materials have a range of meanings but within technology, the current dream is a flexible display screen that can be bent and withstand the ravages of modern living without sacrificing clarity and pixel depth. The concept has existed for quite some time but the questions are, how close and how feasible is the reality? Enter Dr. Jess Wade and her passion for smart polymer materials!
Starting at the beginning, it’s important to take a look at the current run of materials. Sure smart devices have come on leaps and bounds but are they being hamstrung by the medium they are based upon? Silicon is a miraculous material, capable of so many different things, but it’s fairly brittle and inflexible. This is due to its complex molecular structure when used in creating devices. Silicon Doping (no, not the Kim Kardashian kind) is the introduction of different elements, eg. Phosphorus, into the molecular structure in order to augment its properties.
Humans have been doing this kind of thing since we discovered alloys in the Bronze Age, however now that we have far greater control and understanding we are able to incite a whole range of property enhancements. These enhancements have been instrumental in getting Silicon based smart devices to where they are today, but they’re reaching their limits.
Carbon! Carbon is another incredible material that we seem to discover new uses for every other Monday, which is handy considering it’s one of the most abundant elements on Earth. Manipulation of Carbon-6 atoms has been making waves in the form of carbon nanotubes and graphene sheets, materials that seem to have near endless applications.
Carbon nanotubes are amazing structures, capable of electronic conduction, thermal insulation and incredible tensile properties considering their size and weight. Being 50,000 times thinner than a human hair, carbon nanotubes should be hilariously brittle, however weight for weight they are ridiculously durable. This surprising property allows them to be used in a wide range of materials and for a huge number of purposes.
Graphene is a single layer of carbon atoms arranged to form a hexagonal lattice structure. This structure bestows the material with some incredible properties, amongst them is the ability to withstand larger forces than it’s cousin, the carbon nanotube. In fact, it is listed as the strongest material ever tested, on a weight for weight basis of course. As well as it’s unparalleled durability, graphene sheets are nearly transparent and efficient conductors of heat and electrical charges. These properties allow these materials to be applied to an ever-expanding range of products, however, further research into how to utilize them is necessary.
Polyethylene was worthy of a Nobel prize upon its discovery and it’s no surprise why, a careful blend of carbon and hydrogen giving rise to one of the most versatile polymers on the planet? It quite literally reshaped the face of the Earth, not in entirely great ways but that’s a different kettle of frogs altogether. The unique structure available in the form of benzene rings make them great for operations as a conductor and allowing easy movement of delocalized electrons, meaning they can be used in a range of electrical devices with differing effects based on what you tack onto the benzene ring.
Dissolving conjugated organic structures into acetone or a similar liquid is giving rise to a distribution method called Spin coating, capable of creating a surface only a couple of molecules thick. Such surfaces retain their conductive properties and their flexibility, allowing them to be used in creating some interesting devices.
OPV materials are an exciting development that uses an electron donor material and an acceptor material. These materials can consist of just three layers, making it possible to form flexible solar cell materials. The other material making headlines amongst Solar Cell manufacturers is that of Perovskite, a mineral found in most common everyday rocks. It has some incredibly useful properties when it comes to harnessing solar radiation, however, it comes with some massive drawbacks at the moment. Perovskite-based cells are highly efficient but they often contain lead (highly toxic) and leak chlorine gas (also pretty bad for you). Polymer Ink Printing is another highly exciting method but features far lower efficiencies at present. It does, however, allow for exceptionally fast layering and is rapidly improving as our understanding deepens.
But what does that have to do with flexible smart tech? Well, pretty much everything. Solar panels are becoming commonplace, if not mandatory in most locations. The ability to apply these materials to far larger surfaces and make them more flexible, resistant to damage and easier to maintain, has huge implications for the development of technology as energy becomes more readily and cheaply available. Not to mention such layering techniques being combined with other cutting edge techs to develop that mythical flexible smartphone or device that can be folded up and put in a pocket or whatever.
OLED technology is one such advancement that is making that dream a reality one step at a time. OLED materials are fantastic in their ability to emit light when electrically stimulated, however, they aren’t as efficient or effective as possible. OLED devices emit light when excited but only is emissive singlets, releasing just part of the energy. There are studies and research being conducted into improving this property and exploring OLED materials that are able to make use of emissive triplets, tripling the available energy and therefore much better images can be produced.
OLEDs are by no means new, having been used by the tech-giant Samsung for years, they are however rapidly improving and becoming more and more commonly used. What makes OLED materials even better suited for use in displays and screens is the fact that there is no backlighting necessary. As the material itself emits light, there is no need for any form of backlighting device, allowing for thinner material production. Due to this, they have been shown produce higher contrasts in low light environments than LCD surfaces.
In order to identify and test the limits of new and undiscovered materials, AIs are being used in order to help expedite the process. Simulating thousands of different material compositions in a fraction of the time it would take for a lab to test each one manually. These intelligent systems are changing the game when it comes to discovering new technologies and materials.
AIs are useful but not the only things being looked at for inspiration. Humans have been drawing ideas from the natural world ever since we first developed cognitive thought, it’s only natural for us to continue that process after it has served us so well for so long. Naturally occurring nanostructures discovered in animals and insects, such as monarch butterflies, are being investigated in order to aid manufacture of higher resolution displays with more vibrant colors.
Butterflies and Peacocks are known for their impressive and vibrant colorations, what’s more, is that these properties are observable from virtually any angle with little to no distortion. Being able to apply these aspects to a flexible smart-screen would be instrumental in its development and might just be achievable by manipulating chiral molecules in order to alter polarisation of light. Thanks to the structures involved in a large range of OLED compounds, chiral molecules can be easily found and manipulated in order to achieve the desired effects.
Of course, flexible screens and similar devices would be amazing and like something straight out of a sci-fi movie, but plastic electronics are capable of far more. Research being conducted into “Textile Muscles” are gaining momentum, experimenting with fabrics that can expand and contract when an electrical charge is applied. These materials can, therefore, be used to simulate muscle tissue interactions and be used to aid in treating people suffering from muscular damage or other related disorders. These textiles may still be in their early days but there have been some highly impressive results so far!
We may still be quite some time away from owning a smart device that bends and flexes or can be worn around our wrists like some kind of futuristic bracelet terminal computer, but we are making progress. We are expanding our knowledge regarding various polymer-based materials, infusing them with different compounds and elements in order to augment their properties in new and exciting ways.
15 years ago mobile phones were “dumb” and bulky, 10 years ago they were much smarter and beginning to get smaller and sleeker. 5 years ago they were thinner and even smarter with curved displays just beginning to be introduced, now they are thinner and smarter than ever with the majority of them boasting higher resolution displays than ever thought possible. Imagine just where we will be in 5 years time, let alone 10 or 15.