Dynamics of exciton-polariton emission in CuI

We report on temperature-dependent (10 K - 250 K) spectral and dynamical properties of free exciton-polariton and bound exciton emission in copper iodide (CuI) bulk single crystals analyzed by means of time-resolved photoluminescence spectroscopy. The characteristic line shape of the polariton emission at low temperatures is interpreted in terms of the k-linear term effect on the degenerate Z(1,2) excitons in CuI. For free exciton-polaritons, an increase in the decay time with increasing temperature up to 360 ps at 160 K is observed. For bound exciton emission, decay times between 180 ps and 380 ps are observed at low temperatures, revealing the expected EB3/2 dependence of radiative lifetime on the localization energy. Based on the observed rise times of bound excitons at low temperatures, a defect density of shallow acceptors of 1 x 10(17) cm(-3) was estimated, in agreement with measured room temperature free hole density. (c) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0066176

Automated summary

The temperature-dependent spectral and dynamical properties of free exciton-polariton and bound exciton emission in copper iodide bulk single crystals were analyzed, revealing different decay times and localization energy dependencies. The observation of characteristic line shapes and defect densities provides insights into the behavior of excitons in CuI crystals over a wide temperature range.