Self-passivated perovskite solar cells with wider bandgap perovskites as electron blocking layer

Organometallic halide perovskite solar cells (PSCs) have attracted great attention in the past few years owing to their rapid increase of the conversion efficiency and solution-processable fabrication. However, most of the highly efficient PSCs are employing low conductive organic compounds as the electron blocking material, which are still facing the issues of expensive cost and complex fabrication. Here, we present a new architecture of PSCs with gradually enlarged bandgap perovskites self-blocking the charge recombination. The perfect alignment of gradually enlarged bandgap was formed via in-situ ion-exchanging a thin layer of I- by Br- through a simply thermal evaporation method. With the perovskites self-passivation, the electron lifetime was improved 10 times in comparison with the controlled sample. Thus, we obtained a high conversion efficiency of 16.6% with short circuit current of 21.15 mA/cm(2) and open circuit voltage of 1.05 V for the self-passivated PSCs.