Effect of substrate temperature on the performance of Sb2Se3 thin film solar cells fabricated by chemical-molecular beam deposition method

Antimony triselenide (Sb₂Se₃) stands as a promising candidate for photovoltaic (PV) applications due to its favorable material- and optoelectronic properties. However, the realization of further advancements in device efficiency is hindered by the substantial deficit in open-circuit voltage (V_OC) attributed to the presence of multiple defect states and detrimental recombination losses.

In this work, solar cells based on Sb₂Se₃ absorber layers deposited by chemical-molecular beam deposition method at substrate temperatures of 400 °C, 450 °C, and 500 °C. Due to the precise control of the Sb/Se ratio, Sb₂Se₃ thin films with stoichiometric composition were obtained, which was confirmed by energy-dispersive X-ray spectroscopy. The effect of substrate temperature on the morphology and electrical properties of Sb₂Se₃ thin-films were characterized by scanning electron microscopy and hot probe method. The PV performance of Mo/Sb₂Se₃/ZnCdS/CdS/ZnO/ITO/Au devices were investigated by current-voltage characteristics, and external quantum efficiency. The conductivity values tend to increase from 1.2 × 10^–6 to 4.6 × 10^–4 (Ω cm)^-1 as the substrate temperature increased. Whereas, the trap-state density was determined between 7.3 × 10¹³ – 1.7 × 10¹⁴ cm^-3 in the absorber layer by the space charge limited current method. Ultimatety, it has been shown that defect densities in Sb₂Se₃ films can be suppressed to some extent by optimizing the substrate temperature. Best solar cell performance of 5.36%, resulting from V_OC of 476 mV, short-circuit current densit of 22.97 mA/cm⁻², and fill factor of 49% at the substrate temperature of 450 °C.