Diboron-Assisted Interfacial Defect Control Strategy for Highly Efficient Planar Perovskite Solar Cells.

Tu, Yongguang; Yang, Xiaoyu; Su, Rui; Luo, Deying; Cao, Yang; Zhao, Lichen; Liu, Tanghao; Yang, Wenqiang et al. · Adv Mater · 2018

basic_science · Level V

Where this comes from

Abstract

Metal halide perovskite films are endowed with the nature of ions and polycrystallinity. Formamidinium iodide (FAI)-based perovskite films, which include large cations (FA) incorporated into the crystal lattice, are most likely to induce local defects due to the presence of the unreacted FAI species. Here, a diboron-assisted strategy is demonstrated to control the defects induced by the unreacted FAI both inside the grain boundaries and at the surface regions. The diboron compound (C<sub>12</sub> H<sub>10</sub> B<sub>2</sub> O<sub>4</sub> ) can selectively react with unreacted FAI, leading to reduced defect densities. Nonradiative recombination between a perovskite film and a hole-extraction layer is mitigated considerably after the introduction of the proposed approach and charge-carrier extraction is improved as well. A champion power conversion efficiency of 21.11% is therefore obtained with a stabilized power output of 20.83% at the maximum power point for planar perovskite solar cells. The optimized device also delivers negligible hysteresis effect under various scanning conditions. This approach paves a new way for mitigating defects and improving device performance.