Fabrication of efficient and stable perovskite solar cells in open air through adopting a dye interlayer

Abstract

Adding an interface passivation layer on the perovskite is one of the most effective methods to achieve high-efficiency and high-stability perovskite solar cells (PSCs). Herein, a novel dye molecule, namely ethyl-2-((6-hydroxyquinolin-5-yl)diazenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate (HQTh-EC), was synthesized and used as an interlayer between the perovskite absorber layer and the spiro-OMeTAD layer. It was found that the HQTh-EC passivation layer played various roles, such as effectively reducing defect states, enabling appropriate energy level alignment, restraining charge carrier recombination, and accelerating hole extraction. Consequently, the HQTh-EC-optimized PSCs delivered an outstanding power conversion efficiency (PCE) of 20.08%, much improved compared with that of the pristine PSCs (16.73%). Moreover, the HQTh-EC interlayer greatly enhanced the stability of PSCs, which retained 86% of their initial PCE after 400 h aging under ambient air with a relative humidity (RH) of 70–80%. This work provides a useful strategy to simultaneously enhance the performance and stability of PSCs by introduction of a dye interlayer, and will pave the way for fabricating high-performance planar devices under an air environment.