Efficient perovskite light-emitting diodes based on a solution-processed tin dioxide electron transport layer

Abstract

To achieve high-performance perovskite light-emitting diodes (PeLEDs), an appropriate functional layer beneath the perovskite emissive layer is significantly important to modulate the morphology of the perovskite film and to facilitate charge injection and transport in the device. Herein, for the first time, we report efficient n–i–p structured PeLEDs using solution-processed SnO₂ as an electron transport layer. Three-dimensional perovskites, such as CH(NH₂)₂PbI₃ and CH₃NH₃PbI₃, are found to be more chemically compatible with SnO₂ than with commonly used ZnO. In addition, SnO₂ shows good transparency, excellent morphology and suitable energy levels. These properties make SnO₂ a promising candidate in both three- and low-dimensional PeLEDs, among which a high external quantum efficiency of 7.9% has been realized. Furthermore, interfacial materials that are widely used to improve the device performances of ZnO-based PeLEDs are also applied on SnO₂-based PeLEDs and their effects have been systematically studied. In contrast to ZnO, SnO₂ modified by these interfacial materials shows detrimental effects due to photoluminescence quenching.