Organic-inorganic hybrid hole transport layers with SnS doping boost the performance of perovskite solar cells

Abstract

Perovskite solar cells (PSCs) have demonstrated excellent photovoltaic performance which currently rival the long-standing silicon solar cells’ efficiency. However, the relatively poor device operational stability of PSCs still limits their future commercialization. Binary sulfide is a category of materials with promising optoelectrical properties, which shows the potential to improve both the efficiency and stability of PSCs. Here we demonstrate that the inorganic tin monosulfide (SnS) can be an efficient dopant in 2,2′,7,7′-tetrakis(N,N-di-p-methoxy-phenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) to form a composite hole transport layer (HTL) for PSCs. SnS nanoparticles (NPs) synthesized through a simple chemical precipitation method exhibit good crystallization and suitable band matching with the perovskites. The introduction of SnS NPs in Spiro-OMTAD HTLs enhanced charge extraction, reduced trap state density, and shallowed trap state energy level of the devices based on the composite HTLs. Therefore, the resulting solar cells employing SnS-doped spiro-OMeTAD HTLs delivered an improved stabilized power output efficiency of 21.75% as well as enhanced long-term stability and operational stability. Our results provide a simple method to modify the conventional spiro-OMeTAD and obtain PSCs with both high efficiency and good stability.