It’s been a dream of sci-fi fans for years: the flexible, semi-transparent digital newspaper that can fold up and be placed under your arm. That dream is a tad bit closer to reality today as Chinese researchers have released a video of their recent developments in creating the necessary materials for further developing flexible and transparent silicon semiconductors. The best way to wrap your head around it? Imagine if a sheet of Jolly Rancher was turned into Cotton Candy.
When looking ahead at the intersection of wearable technologies and Moore’s Law, it might come with little surprise that not only are computers becoming smaller and more fashionably acceptable, but, like recent developments in user interfaces—more invisible. Flexible displays have been seeing their own share of attention in recent memory, but little can be done when the rest of the system can’t flex along with it.
Chengxing Wang of Sun Yat-sen University in Guangzhou, China and his colleagues recently found success in creating flexible and transparent silicon ‘paper’ by placing silicon monoxide powder inside of a crucible and vaporized it at a temperature of 1600 C degrees. Using a stream of argon gas to push the vapor to the top of a crucible, the cooling reaction formed particles of silicon and silicon dioxide that resulted in the silicon sticking together in the form of nano-wires held together like fiber in traditional paper or steel wool. Ultimately, despite sharing the same rigid crystal properties seen in the chips of today’s most advanced electronics, the resulting paper-like structure is able to bend freely without snapping. Due to the unique nano-scale properties of the paper, light is able to pass through freely giving the final material transparent properties.
Currently, Wang and his crew are focusing on creating large sheets of the nano-wires with uniform thickness that can be used for industrial applications. Having the new silicon paper is one thing, but transparent, too? That’s like getting an XBox and a Playstation for Christmas.
If the flexible transparent and free-standing paper-like materials that would be expected to meet emerging technological demands, such as components of transparent electrical batteries, flexible solar cells, bendable electronics, paper displays, wearable computers, and so on, could be achieved in silicon, it is no doubt that the traditional semiconductor materials would be rejuvenated. Bulk silicon cannot provide a solution because it usually exhibits brittleness at below their melting point temperature due to high Peierls stress. Fortunately, when the silicon’s size goes down to nanoscale, it possesses the ultralarge straining ability, which results in the possibility to design flexible transparent and self-standing silicon nanowires paper (FTS-SiNWsP). However, realization of the FTS-SiNWsP is still a challenging task due largely to the subtlety in the preparation of a unique interlocking alignment with free-catalyst controllable growth. Herein, we present a simple synthetic strategy by gas flow directed assembly of a unique interlocking alignment of the Si nanowires (SiNWs) to produce, for the first time, the FTS-SiNWsP, which consisted of interconnected SiNWs with the diameter of 10 nm via simply free-catalyst thermal evaporation in a vertical high-frequency induction furnace. This approach opens up the possibility for creating various flexible transparent functional devices based on the FTS-SiNWsP.
-Chunlei Pang, Hao Cui, Guowei Yang, and Chengxin Wang
(source: ACS Publications)