A Ga-doped SnO2 mesoporous contact for UV stable highly efficient perovskite solar cells

Abstract

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 TiO₂ (m-TiO₂). One of the major causes of performance loss in these m-TiO₂-based perovskite solar cells is induced by UV-radiation. This UV instability can be solved by replacing TiO₂ with SnO₂; thus developing a mesoporous SnO₂ (m-SnO₂) perovskite solar cell is a promising approach to maximise efficiency and stability. However, the performance of mesoporous SnO₂ (m-SnO₂) perovskite solar cells has so far not been able to rival the performance of TiO₂ based perovskite solar cells. In this study, for the first time, high-efficiency m-SnO₂ perovskite solar cells are fabricated, by doping SnO₂ with gallium, yielding devices that can compete with TiO₂ based devices in terms of performance. We found that gallium doping severely decreases the trap state density in SnO₂, 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-SnO₂ based perovskite solar cells is underlined by stability data, showing a marked increase in stability under full solar spectrum illumination.