Defects and passivation in perovskite solar cells

This organic-inorganic hybrid perovskite materials have attracted great attention by virtue of their high absorption coefficient, low cost and simple film deposition technique. Based on these advantages, perovskite solar cells have reached an impressive power conversion efficiency over 25%. However, the low-temperature process inevitably leads to a large number of defects in the perovskite film. These defects would exacerbate the carrier recombination, induce crystal degradation, phase transformation and seriously affect the performance of devices. Studying the defects in perovskite film is of great significance for the development of high-performance perovskite solar cells. Herein, the authors summarise the causes, distribution and features of defects, as well as their effects on the performance of perovskite solar cells. Furthermore, some defect-passivation strategies on perovskite film or the device, including grain boundary passivation, surface passivation, capping layer modification and charge transport layer passivation, are discussed, respectively. Lastly, some remaining challenges in the commercialisation of perovskite solar cells are proposed.