Dual-functionalized poly(ethylene oxide) for interface modification and addition of rubidium-doped CsPbBr3 perovskite composite emission layer to enhance brightness of perovskite light-emitting diodes

Abstract

Metal halide perovskite as an emitter has extremely high color purity, but the generally poor morphology of the perovskite layer restricts the performance of the emitter. The additive of a suitable polymer can greatly boost the uniformity of the spin-coated perovskite film. The all-inorganic perovskite layer deposited by the solution method has a multi-crystalline structure. Besides, there are a lot of defects and grain boundaries on the surface, and the carriers will undergo non-radiative recombination at these defects. In this study, Cs1-xRbxPbBr3 was prepared by introducing Rb+ cations with smaller ionic radius to partially replace Cs+ cations, and combined with poly(ethylene oxide) (PEO) and (1,3,5-benzinetriyl)tris(1-phenyl-1-H-benzimidazole) (TPBi) blended composite film as the light-emitting layer, that can increase the film coverage and radiative recombination efficiency of the perovskite film. The polymer PEO was introduced as a buffer layer deposited on the poly-TPD hole transport layer (HTL) to to enhance the hydrophilicity and passivate the poly-TPD HTL/perovskites interface in order to obtain high-efficiency perovskite light-emitting diodes. By adjusting the concentration of the PEO buffer layer, the champion luminance and external quantum efficiency are 25650 cd/m2 and 0.844 %, respectively.