A strategy for improving the performance of perovskite red light-emitting diodes by controlling the growth of perovskite crystal

Abstract

Small Cs_0.8FA_0.2PbI₃ perovskite crystal grains with α-phase structure were prepared by a one-step spin-coating method using both polyethylene oxide (PEO) and 1-naphthylmethyl ammonium iodide (NMAI). A red light-emitting device based on the Cs_0.8FA_0.2PbI₃ perovskite with the structure of glass/ITO/PEDOT:PSS/Cs_0.8FA_0.2PbI₃/TPBi/LiF/Al was prepared, which displayed an emission peak at 698 nm, a maximum brightness of 176 cd m⁻², and an external quantum efficiency of 2.6%. The device showed a half-lifetime of 30 min at an initial luminance of 60 cd m⁻². Systematic investigation revealed that the addition of both PEO and NMAI to perovskites could promote the formation of α-phase perovskite, reduce perovskite grain size, improve the coverage and uniformity of the film, and increase the exciton binding energy, thus enhancing the combination of excitons and improving the stability of α-phase perovskite structures. This result may lead to a novel way to fabricate stable polycrystalline-based red perovskite light emitting diodes.