Tin antimony sulfide (Sn6Sb10S21) thin films by heating chemically deposited Sb2S3/SnS layers: Studies on the structure and their optoelectronic properties

Abstract

Tin antimony sulfide thin films (Sn6Sb10S21) were obtained on glass substrates by heating chemical bath deposited Sb2S3/SnS layers. The report primarily focuses on the structure, composition, morphology, optical and electrical properties of the thin films formed at the temperature range of 300–450 °C for 30 min as well as at the optimized temperature of 390 °C for 1, 2 and 3 h in low vacuum. X-ray diffraction and Raman analysis revealed the crystallization of ternary phase Sn6Sb10S21 at temperatures higher than 390 °C. X-ray photoelectron study identified the presence of Sn2+, Sb3+ and S2- states in the ternary phase and the depth profile analysis exhibited a uniform distribution of elements throughout the thickness. Further, surface morphology of the as-deposited and annealed thin films were examined using scanning electron microscopy. The optical band gaps calculated from the UV–Vis–NIR spectra were in the range of 1.26–1.45 eV with significantly high absorption coefficients (∼105 cm−1) which is ideal for photovoltaic conversion. Moreover, the thin films were photoconductive and when incorporated into the photovoltaic structure, Glass/FTO/CdS/ASTS/C–Ag, demonstrated photovoltaic performance. The corresponding parameters Voc, Jsc, and FF were evaluated from the J-V curves yielding the values 409 mV, 1.46 mAcm−2 and 0.25 respectively.