Effects of ZnSe modification on the perovskite films and perovskite solar cells based on ZnO nanorod arrays

Abstract ZnO as electron transfer layer in perovskite solar cells (PSCs) has a lot of advantages including high electron mobility and low processing temperature. However, because of the reported instabilities of perovskite layers deposited on ZnO, the application of ZnO in perovskite solar cells has been restricted. In this paper, highly ordered ZnO nanorod arrays have been synthesized by a polymer soft template method, and then modified by ZnSe via a successive ion layer adsorption and reaction method (SILAR). Field emission scanning electron microscope, X-ray diffractometer, UV–vis spectrophotometer, fluorophotometer and photovoltaic measurements were used to study the effects of ZnSe modification on the morphology, structure, light absorption and charge transfer of perovskite films and the performance of the PSCs based on ZnO nanorod arrays. The photoelectric conversion efficiency (PCE) of the PSC with ZnSe modification significantly enhanced by 27%, as compared to that of the pristine one, which is attributed to the suitable band alignment, better carrier separation and higher charge transfer efficiency with ZnSe modification. Meanwhile, ZnSe modification can also improve the air stability of the PSCs. This study promotes the development of ZnO nanorod arrays based PSCs with some new approaches and provides a useful reference.