Electron Versus Hole Extraction: Self Doping Induced Performance Bottleneck in Perovskite Solar Cells

Efficient and balanced collection of photo-generated charge carriers is a fundamental requirement for high efficiency solar cells - including perovskites. Any process or bias induced asymmetry in carrier collection leads to degradation in efficiency. Here, for the first time, we show that process induced self-doping in the perovskite active layer could result in asymmetric carrier collection. Accordingly, interface quality at the majority carrier collection layer becomes the performance limiting factor in perovskite solar cells. Through detailed numerical simulations we identify optimization schemes to overcome the ill-effects due to self-doping and interface recombination. Further, the insights on asymmetric carrier collection has interesting implications on regular vs. inverted geometry and long term stability of perovskite solar cells - which could be of broad interest to the community.