Physicists at ITMO University have discovered a new way to use transparent materials in solar cells while maintaining their efficiency. The new technology is based on doping methods, which change the properties of materials by adding impurities but without the use of expensive specialized equipment.

The results of this research have been published in ACSApplied Materials & Interfaces (“Ion-gated small molecule OPVs: Interfacial doping of charge collectors and transport layers”).

One of the most fascinating challenges in solar energy is the development of transparent thin-film photosensitive materials. The film can be applied on top of ordinary windows to generate energy without affecting the appearance of the building. But developing solar cells that combine high efficiency with good light transmittance is very difficult.

Conventional thin-film solar cells have opaque metal back contacts that capture more light. Transparent solar cells use light-transmitting back electrodes. In this case, some photons are inevitably lost as they pass through, degrading the device’s performance. Furthermore, producing a back electrode with appropriate properties can be very expensive,” says Pavel Voroshilov, a researcher at ITMO University’s School of Physics and Engineering.

The problem of low efficiency is solved by using doping. But ensuring the impurities are applied correctly to the material requires complex methods and expensive equipment. Researchers at ITMO University have proposed a cheaper technology to create “invisible” solar panels – one that uses ionic liquids to dope the material, which changes the properties of the processed layers.

 ”For our experiments, we took a small molecule-based solar cell and attached nanotubes to it. Next, we doped the nanotubes using an ion gate. We also processed the transport layer, which is responsible for making The charge from the active layer successfully reaches the electrode. We were able to do this without a vacuum chamber and working under ambient conditions. All we had to do was drop some ionic liquid and apply a little voltage to produce the necessary performance. ” added Pavel Voroshilov.

 In testing their technology, the scientists were able to significantly increase the battery’s efficiency. The researchers believe the same technology could be used to improve the performance of other types of solar cells. Now they plan to experiment with different materials and improve the doping technology itself.