Experimental and modeling analysis of photocarrier dynamics in CZTSSe using temperature-dependent photoluminescence

Abstract

CZTSSe shows great potential in photovoltaic applications. However, the device efficiency is limited by the high density detrimental defects in the absorber. Therefore, investigating the influence of defects on absorber properties is essential. In this study, temperature-dependent steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements were performed on a CZTSSe film. Four emission components involving defect-associated transitions were obtained by analyzing the PL spectra. Beyond the traditional exponential analysis, a diffusion-recombination model was applied to simulate the TRPL curves, by which the key parameters describing the carrier recombination and diffusion were extracted. The model includes defect-mediated and band-involved recombination rates, surface/interface recombination velocities and their corresponding temperature dependences. The results indicate that the increasing Shockley–Read–Hall recombination rate is the dominant factor that leads to the enhanced PL quenching with increasing temperature. Our results help to further explain the key factors that influence the optoelectronic properties of CZTSSe.