Perovskite/PTAA Bulk Heterojunction for High Efficient Carbon-Based Large-Area Solar Cells by Gradient Engineering.

The performance of low-temperature carbon-based perovskite solar cells (C-PSCs) with high commercial potential was hampered by the inferior interface between absorber and carbon electrode. In this work, PTAA was dissolved in anti-solvent for spin-coating perovskite (CH3NH3PbI3, MAPI) films, which was applied to modify both the MAPI films and the interface between MAPI layer and carbon electrode by gradient engineering. Finally, the C-PSCs based on MAPI-PTAA gradient bulk heterojunction (GBH) films achieved a power conversion efficiency of 13.0% with active area of 1 cm2, 26% higher than that of pristine MAPI cells, due to the passivated trap states, accelerated hole extraction and improved crystalline properties in absorber films.