Self-Assembled High Quality CsPbBr₃ Quantum Dot Films toward Highly Efficient Light-Emitting Diodes

Abstract

Full inorganic cesium lead halide perovskites (IOPs) are regarded as attractive candidates for light-emitting diodes (LEDs) by their excellent luminescent conversion. However, unsatisfactory efficiency and stability are still the main drawbacks that hinder the commercialization progress of perovskite LEDs (PeLEDs). Here, we report an extremely uniform and flat CsPbBr₃ film composing of self-assembly core-shell structured quantum dots (SCQDs) based on one-step precursor coating. The QDs size in the CsPbBr₃ film is around 4.5 nm (smaller than the Bohr radius), which significantly confines injected carriers and leads to a ultrahigh exciton binding energy ( E_b) of 198 meV. In addition, unfavorable surfacial defects are dramatically passivated by a thin surfacial-capping layer composed of long-chain ammonium groups (phenylalanine bromide, PPABr), resulting in an ultralow nonradiative recombination rate. Consequently, the CsPbBr₃ SCQDs film presents a high photoluminescence quantum yield (PLQY) of 85%. It enables the resulting green PeLEDs to deliver a recorded external quantum efficiency (EQE) over 15% with ideal operational stability. Furthermore, the developed CsPbBr₃ SCQDs film also demonstrates promising potential in multifunctional lighting sources such as flexible and smart devices.