N-type Doping of Organic-Inorganic Hybrid Perovskites Toward High-Performance Photovoltaic Devices

The disparity of hole and electron behavior is a ubiquitous issue in methylammonium lead halide perovskites. The carrier mobility imbalance, which will result in a built-in electric field thus increase the device resistance, is regarded as one of main limiting factors for the further improvement of device performance in perovskite solar cells (PSCs). Here, we realized an n-doped organic-inorganic hybrid perovskite by directly incorporating AgI into the CH3NH3PbI3 precursor solution, to fabricate high-performance PSCs. AgI doping resulted in a balanced charge transporting owing to a remarkable increase in the electron mobility, which was attributed to the aligned orientation of MA(+) ions owing to the Ag+-influenced distribution of electron cloud density. Meanwhile, AgI could act as an additive to control the perovskite crystallization with improved crystallinity and film morphology. Consequently, a maximum power conversion efficiency of over 20% is achieved. The finding in this work provides a direction to fabricate high-performance PSCs by controlling the charge balance via intensive doping technique.