In-Situ Growth of Perovskite Stacking Layer for High-Efficiency Carbon-Based Hole Conductor Free Perovskite Solar Cells
The interfacial properties between the perovskite layer and carbon electrode are critical for the photovoltaic performance of the carbon electrode-based perovskite solar cells (PSCs). Herein, a methylammonium lead mixed halide (MAPbIxBr3-x) perovskite layer in-situ grows on the top of methylammonium lead iodide (MAPbI3) perovskite layer forming MAPbI3/MAPbIxBr3-x perovskite stacking structure (PSS) to improve the interfacial properties at the perovskite/carbon electrode interface. The charge carrier dynamics in both perovskite and PSC device induced by the MAPbIxBr3-x perovskite stacking layer are studied using extensive characterizations. The charge interfacial recombination at the perovskite/carbon electrode interface is significantly diminished using the PSS within PSC, resulting in largely improved charge extraction and therefore high photovoltaic performance. The PSS-based PSC shows a power conversion efficiency up to 16.2% (increased by 43% compared with that of the conventional MAPbI3-based PSC), which is among the highest efficiency of the carbon electrode-based hole conductor free PSCs. Meanwhile, the PSS-based PSC exhibits good stability under both continuous illumination and storage under dark condition. This work may provide a new avenue to fine control the interfacial properties of carbon electrode-based PSC for further improving photovoltaic performance.