A Ga-doped SnO mesoporous contact for UV stable highly efficient perovskite solar cells

Increasing the stability of perovskite solar cells is a major challenge for commercialization. The highest efficiencies so far have been achieved in perovskite solar cells employing mesoporous TiO 2 (m-TiO 2 ). One of the major causes of performance loss in these m-TiO 2 -based perovskite solar cells is induced by UV-radiation. This UV instability can be solved by replacing TiO 2 with SnO 2 ; thus developing a mesoporous SnO 2 (m-SnO 2 ) perovskite solar cell is a promising approach to maximise efficiency and stability. However, the performance of mesoporous SnO 2 (m-SnO 2 ) perovskite solar cells has so far not been able to rival the performance of TiO 2 based perovskite solar cells. In this study, for the first time, high-efficiency m-SnO 2 perovskite solar cells are fabricated, by doping SnO 2 with gallium, yielding devices that can compete with TiO 2 based devices in terms of performance. We found that gallium doping severely decreases the trap state density in SnO 2 , leading to a lower recombination rate. This, in turn, leads to an increased open circuit potential and fill factor, yielding a stabilised power conversion efficiency of 16.4%. The importance of high-efficiency m-SnO 2 based perovskite solar cells is underlined by stability data, showing a marked increase in stability under full solar spectrum illumination. Increasing the stability of perovskite solar cells is a major challenge for commercialization.