Efficient blue CsPb(Br–Cl)3 nanoparticles enabled by strontium halide and amine halide synergetic optimization

Abstract

Blue emitting CsPb(Br–Cl)₃ perovskite nanoparticles (NPs) play an important role in optoelectronic applications. However, the synthesis of stable blue perovskite NPs with excellent photoluminescence quantum yield (PLQY) is still challenging. Here, a new strategy of conveniently using strontium halides and amine halides for simultaneous doping and surface passivation of CsPb(Br–Cl)₃ perovskite NPs is proposed. Through experimental studies and calculations, it is found that divalent Sr²⁺ cations can partly replace the B-site Pb²⁺ ions in the lattice structure of perovskite NPs and cause a slight lattice contraction, not only passivating the defects but also providing chances for bluer NPs. As a result, the deep-blue CsPb(Br–Cl)₃ perovskite NPs with PL emission centered at 455 nm and a high PLQY of 96% were obtained. In addition, a white light-emitting device (WLED) with the NPs as an emissive layer exhibited a maximum power efficiency of 76 lm W⁻¹ with Commission International de L’Eclairage (CIE) coordinates of (0.33, 0.34). These findings provide fundamental insights into the excited state dynamics of colloidal cesium lead halide (CsPbX₃) perovskite NPs that can be used as components of LEDs for practical applications.