Additive Combining Passivator for Inverted Wide‐Bandgap Perovskite Solar Cells with 22% Efficiency and Reduced Voltage Loss

Abstract

Wide‐bandgap (WBG) perovskite solar cells (PSCs) play a crucial role in tandem devices. However, the severe non‐radiative recombination that occurs at interface between perovskite and electron transport layers (ETL) leads to excessive open‐circuit voltage (VOC) loss, which hinders the further improvement of the photovoltaic conversion efficiency (PCE). To mitigate the VOC loss in wide‐bandgap perovskite solar cells, we can reduce the defects exist in grains and grain boundaries as well as optimize the energy level alignment between perovskite layer and ETL, so as to improve the carrier collection efficiency. In this paper, potassium thiocyanate (KSCN) is introduced as an additive and 2‐thiophenethylammonium bromide (TEABr) is used to passivate perovskite/C60 interface. The synergistic treatment reduces the defect density and prolongs the carrier lifetime, implying that the non‐radiative recombination is effectively suppressed. Meanwhile, the energy level alignment of the perovskite and C60 is optimized, leading to the improvement of VOC. Finally, WBG perovskite solar cells with a band gap of 1.68 eV achieve a VOC of 1.22 V (with a VOC loss of 0.46 V) and a PCE of 22.02%.This article is protected by copyright. All rights reserved.