Temperature sensitivity of adjustable band gaps of Sb2(S, Se)3 solar cells via vapor transport deposition

Abstract

Quasi-one-dimensional antimony chalcogenide Sb2(S, Se)3 semiconductor is regarded as one of the most promising photovoltaic materials due to their high optical absorbance coefficient and tunable band gaps. However, current researchers rarely optimize experimental conditions based on characteristics of the Se/S ratio in Sb2(S, Se)3 material and ignore the experimental optimization based on material characteristics. Herein, Sb2(S, Se)3 thin films with three different Se/(Se + S) ratios (Se = 0.2, 0.5, 0.8) are prepared by vapor transport deposition (VTD) based on the temperature sensitivity of the evaporator source. The influence of VTD conditions of Sb2(S, Se)3 on optical properties, electrical properties, film quality, and defect characteristics are investigated through UV absorbance spectra, current density versus voltage (J-V) measurements, scanning electron microscopy (SEM), deep-level transient spectroscopy (DLTS), respectively. It is concluded that the deposition temperature is closely associated with the shift of the band gap. Moreover, different original Se/(Se + S) ratios yield different optimum temperatures (Se = 0.2, 480 °C; Se = 0.5, 500 °C; Se = 0.8, 520 °C), and optimum temperature increase with Se atom ratios. With optimization of the Se/(Se + S) ratio and deposition temperature, a Sb2(S, Se)3 solar cell (Se = 0.8) prepared under 520 °C has optimal light absorbance, longer carrier lifetime, and better film quality, displaying a high efficiency of 6.78%.