Amorphous AlO6–SnO2 nanocomposite electron-selective layers yielding over 21% efficiency in ambient-air-processed MAPbI3-based planar solar cells

Abstract

Despite intensive efforts to increase the power conversion efficiency (PCE) of perovskite solar cells (PSCs), the inevitable stress/strain that is occurred in devices and diverse defects generated during the solution process make achieving the theoretical limit of PSCs difficult. Herein, a novel AlO6–SnO2 nanocomposite electron-selective layer (ESL) is reported, where amorphous AlO6 is distributed uniformly in an amorphous SnO2 network film. Compared with a pristine-SnO2 ESL, an amorphous AlO6–SnO2 ESL increases the size of the perovskite grains achieving a low grain-boundary density, reduces the stress acting as an internal and interfacial nonradiative recombination pathway, exhibits high conductivity and fast charge extraction, and achieves an ideal band offset by upshifting the Fermi level. Through the synergistic multiple-passivation of the AlO6–SnO2 ESL, a PCE of 21.04% with a conventional ambient-air-processed methylammonium lead iodide film. In addition, the AlO6–SnO2-based PSCs exhibit improved stability and reduced hysteresis, making them promising materials for planar PSC applications.