Tetrahedrite copper antimony sulfide (Cu12Sb4S13) thin films for photovoltaic and self-powered photodetector applications grown by single step ultrasonic spray pyrolysis

This work reports in situ growth of tetrahedrite Cu12Sb4S13 thin films via ultrasonic spray pyrolysis using a nonaqueous solution containing CuCl2, SbCl3 and C2H5NS. The thin films deposited by varying S/(Cu + Sb) ratios in the precursor solution were studied using X-ray diffraction and Raman spectroscopy to evaluate the phase formation. Optical characterization showed a direct band gap of nearly 1.5 eV, consistent with the theoretical simulation of electronic band structure and optical spectra based on First principles calculations. Cu12Sb4S13 thin films formed as a function of S/(Cu + Sb) precursor ratio spans semiconducting (p) to semi-metallic (p+) behavior, confirmed by Hall effect. Photodetection properties of the p type Cu12Sb4S13 films showed a spectral response ranging from UV to visible and NIR wavelengths. Both p and p+ thin films were incorporated into photovoltaic structures using CdS as window layer, resulting: Voc = 0.273-0.398 V, Jsc = 2.5-16.3 mAcm  2, FF = 32-35% and efficiency = 0.33-1.4%. These heterostructures also performed as self-powered photodiodes for UV-Vis-NIR wavelength detection. This is the first report of a single-step synthesis of phase pure Cu12Sb4S13 thin films and their performance as self-biased photodiode and photovoltaic devices.