Perovskite Crystallization and Hot Carrier Dynamics Manipulation Enables Efficient and Stable Perovskite Solar Cells with 25.32% Efficiency

Abstract

AbstractModulating perovskite crystallization and understanding hot carriers (HCs) dynamics in perovskite films are very critical to achieving high‐performance perovskite solar cells (PSCs). Herein, a small organic molecule (6BAS) with multisite anchors (C═O) as an efficient additive is introduced into PbI2 precursors to modulate perovskite crystallization during two‐step sequential deposition. The chemical interaction between 6BAS and PbI2 enables more preferential PbI2 crystal with enlarged interplanar spacing of PbI2 lattice, which is beneficial to the penetration of organic ammonium salts into PbI2 layer and the complete conversion to perovskite, consequently promoting the preferential crystallization of perovskite to realize high‐quality perovskite films with larger grain size and reduced defect state. By ultrafast spectroscopy, it is found that the incorporation of 6BAS can efficiently prolong HCs cooling, which helps to enhance HCs transfer and retard the charge carrier recombination in device. As a result, 6BAS doped‐PSCs efficiency significantly enhances to 25.32% from 22.91%. The target device achieves the enhanced long‐term stability. Only a 6% efficiency degradation is realized for un‐encapsulated device with 6BAS after 70 days under N2. Meanwhile, the 6BAS‐treated device retains 95% of its initial PCE after 1160 h of operation at the maximum power point under continuous AM 1.5 G illumination.