A team of Chinese and US scientists from Shenzhen Institute of Technology, Shijiazhuang Tiedao University, Peking University, Argonne National Laboratory, Institute of Metal Research, and University of Washington, have grown a monocrystalline version of a perovskite solar cell.
The created cell is reportedly of high quality and firmly incorporated on FTO/TiO2. To create it, the team has taken advantage of capillary effect and temperature gradient during the growth process. This achievement is considered to be critical, since FTO/TiO2 is regarded as the most extensively used electron-collecting substrate for perovskite solar cells, making the succeeding device fabrication straightforward. Although it won’t replace monocrystalline silicon cells anytime soon (the new cell’s efficiency is only 9%), it’s the first time perovskite has been grown as a single cell.
Perovskite-based cells are commonly based on polycrystalline CH3NH3PbI3 films. As with any polycrystalline structure, it is more susceptible to defects that can lower performance. The single crystalline CH3NH3PbI3 film, however, could help in that arena. It exhibits exceptional photovoltaic properties; The time-resolved photoluminescence, measured directly on FTO glass substrate with poor electron extraction, exhibits a much extended carrier lifetime in single crystalline CH3NH3PbI3 film compared to the polycrystalline one. The charge carrier lifetime drops considerably when a TiO2 electron collecting layer is added on top of FTO glass, thanks to the effective electron extraction at the TiO2/perovskite interface. The device this exhibits photovoltaic conversion efficiency of 8.78%, considered to the highest reported to date for a single crystalline perovskite solar cell. The team highlighted that the system is capable of being further improved, and with constant optimization of devices and materials, they assume that the single crystalline perovskite solar cells will compete with their polycrystalline counterparts in the predictable future.