UC Berkeley

Metal halide perovskites have excellent optoelectronic properties. This study aims to determine how the optoelectronic properties of a model perovskite, cesium lead bromide (CsPbBr₃), change with length and thickness in one dimension (1D). By examining the photophysics of CsPbBr₃ quantum dots (QDs), nanowires (NWs), and nanorods (NRs), we observe the influence of confinement, exciton diffusion, and trapping on their optical properties. Our findings reveal that exciton diffusion to trap states limits the photoluminescence quantum yield (PLQY) of 1D CsPbBr₃ in the weakly confined regime (8-14 nm) and explains their long-lived exciton dynamics, while enhanced radiative rates contribute to achieving near-unity PLQY in the strongly confined regime (<7 nm). Consequently, blue-emitting, 2.4 nm-thick CsPbBr₃ NRs were 3.6X more emissive than the conventional CsPbBr₃ QDs. This study underscores how structural optimization can improve the optoelectronic performance of CsPbBr₃ and provides insight into the complex interplay of radiative and nonradiative processes in 1D ionic semiconductors.