Enhanced defect luminescence due to fast Auger process in cuprous iodide structures produced by solvent/anti-solvent crystallization

Photoluminescence spectra of self-assembled cuprous iodide structures produced by solvent-antisolvent crystallization were investigated over eight orders of magnitude of excitation power density. Through an analysis of the effects of different annealing conditions on the emission spectra two defects-related emissions, associated to copper and iodine vacancies, and a free exciton recombination peak were identified. At higher power densities, an enhanced increase in the broad defects-related emission band accompanied by a decrease in other contributions was observed. A fast, non-radiative Auger process is proposed as the main mechanism allowing high energy electrons to be trapped at deep level defects associated to the broad defects-related emission band while simultaneously reducing the amount of free charge carriers, which results in the observed behavior. With a rate-equation model developed for the proposed mechanism a close fit between simulated and experimental data was achieved.