bright triplet excitons in caesium lead halide perovskites

BRIGHT TRIPLET EXCITONS IN CAESIUM LEAD HALIDE PEROVSKITES PDF

More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. Bright triplet excitons in caesium lead halide perovskites. and have recently been harnessed very successfully for high-efficiency photovoltaics and bright light sources. The existence of this bright triplet exciton is further confirmed by analysis of the fine structure in low-temperature fluorescence spectra. Single Cesium Lead Halide Perovskite Nanocrystals at Low Temperature: Fast Single-Photon Emission. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temperatures, respectively. We then apply our model to CsPbX 3 nanocrystals, and measure size- and composition-dependent fluorescence at the single-nanocrystal level. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. Bright Triplet Excitons in Caesium Lead Halide.

BRIGHT TRIPLET EXCITONS IN CAESIUM LEAD HALIDE PEROVSKITES PDF

Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX 3, with X = Cl, Br or I) involves a highly emissive triplet state. PDF The recent emergence of metal halide perovskites as triplet sensitizers has generated new possibilities in optoelectronics. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright. It was found recently that, for cesium lead-halide perovskite NCs, their unusually efficient light emission may be due to a unique excitonic fine structure. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the 'dark exciton'. For organic materials, Hund's rules state that the lowest-energy exciton is a poorly emitting triplet state.

Lead halide perovskite has been a promising candidate in spintronics applications while the mechanism of spin relaxation is still. Nanostructured semiconductors emit light from electronic states known as excitons. Nanjing University of Posts and Telecommunications.