Efficient and Stable Blue Perovskite Light-Emitting Devices Based on Inorganic Cs₄PbBr₆ Spaced Low-Dimensional CsPbBr₃ through Synergistic Control of Amino Alcohols and Polymer Additives

Perovskite light-emitting devices (PeLEDs) have drawn a great deal of attention because of their exceptional optical and electrical properties. However, as for the blue PeLEDs based on low-dimensional (LD) CsPbBr3, the low conductivity of the widely used organic spacers as well as the difficulty of forming pure and uniform LD CsPbBr3 phase have severely inhibited the device performance such as stability and efficiency. In this work, we report an effective strategy to obtain high-quality LD CsPbBr3 by using a novel spacer of inorganic Cs4PbBr6 instead of the common long-chain ammonium halides. We found that a 3-amino-1-propanol (3AP)-modified PEDOT:PSS was helpful to stimulate the formation of the LD blue emissive CsPbBr3:Cs4PbBr6 composite. We also revealed that an additive of poly(vinylpyrrolidone) (PVP) in the precursor can limit further growth of LD perovskite phase into 3D perovskite phase upon annealing, thus resulting in a uniformly distributed LD perovskite with high color stability. Consequently, efficient blue PeLEDs @ 485 nm with a brightness of 2192 cd/m2, current efficiency of 2.68 cd/A, and external quantum efficiency of 2.3% was successfully achieved. More importantly, the device showed much improved working stability compared to those with the spacer of organic ammonium halides. Our results provide some helpful insights into developing efficient and stable blue PeLEDs.