CH₃NH₃PbI₃ deposited on rubrene/pentacene bilayer by two-step method and its photovoltaic performance

Abstract Optimizing the underlayer used as an active layer in perovskite solar cells is important for improving their cell performance. We previously demonstrated the usefulness of a rubrene/pentacene bilayer as an underlayer in CH 3 NH 3 PbI 3 (MAPbI 3 ) cells prepared by alternative vapor deposition of PbI 2 and CH 3 NH 3 I (MAI). In the present work, to examine the applicability of this rubrene/pentacene bilayer for the deposition of MAPbI 3 via a new method involving immersing a PbI 2 evaporated film into an MAI solution is used to prepare MAPbI 3 films; this method is referred to as a two-step method. Adjustment of the parameters of the two-step method used to prepare MAPbI 3 films on rubrene/pentacene bilayers led to cells with a higher power conversion efficiency compared with that of cells with MAPbI 3 films deposited directly onto poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), without rubrene/pentacene bilayers. The rubrene/pentacene presumably promotes the suppression of recombination at the interface between MAPbI 3 and the hole transport layer.