Scientists Show A Way To Create Optical Chips And Solar Cell Details From Perovskite

It’s not a common thing in modern science when the results of one research give significant application results in three different fields of technology. Physicists from ITMO University and their colleagues from Far Eastern Federal University (FEFU) succeeded in conducting a series of experiments on laser processing of perovskite. They used their results to show how to create solar cells of any color, churn out millions of nanolasers for future optical transistors, as well as inscribe information that can only be read by those who it was intended for. The results were published in Small.

Perovskites are a class of materials with a specific crystalline structure. They were first discovered in the first half of the 19th century in the Ural region as a mineral that consisted of calcium, titanium and oxygen atoms. From then on, perovskites were applied in both nonlinear optics and the manufacturing of semiconductors. Now, they are rapidly winning the ground in the fields of solar power industry and photonics: in 2013, research on the use of these materials made it into Science’s top ten breakthroughs, as new organic-inorganic perovskites already pose a competition to silicon and gallium arsenide.

Perovskites can be used to create tiny lasers that are smaller than the size of the lightwave they emit. At the same time, these light sources can be easily adjusted in the visual band, or, to put it simply, their signal can be of different colors. But there’s a price to pay: it’s quite hard to create miniscule perovskite structures, something of tens of nanometers in size. This hinders the active industrial introduction of this material.

Laser etching
Apart from a high sensitivity to etching reagents, perovskites have another feature: extremely low heat conductivity. Perovskites transfer heat even worse than glass. So, scientists from ITMO University and Far Eastern Federal University (FEFU) proposed a method for processing perovskite with the help of a laser.

Researchers from St. Petersburg prepared the material which was then processed at Far Eastern Federal University with the help of a femtosecond laser and a precise positioning system. Scientists from Vladivostok, who are very experienced in nanostructuring, created laser beams with a specific profile.

Colored solar cells, nanolasers and information inscription

An ultrashort impulse from a femtosecond laser doesn’t heat a wide area while cutting a nanostructure in a tiny location where the scientists need it. Experiments showed that a femtosecond laser can not just cut through the material but also make grooves of various forms that are about several hundred nanometers wide without affecting the material’s optical properties.

In the associated research, scientists described several applications for the new technology. The first is to inscribe information on a perovskite in such a way that it would be possible to read it only under specific conditions.

But that’s not all: a laser can also be used to change a perovskite’s visible color without using a colorant. The material can appear yellow, black, blue or red depending on your tasks.

Finally, the third application is the manufacturing of nanolasers for optical sensors, and in the future - for optical computers, as well, where information will be transferred with the movement of photons rather than electrons. Finding a solution for the fast, cheap and simple manufacturing of such elements is one of the problems that stands in the way of a new age of computational technology that’s based on light.