Photoconductive thin films of AgSbS 2 with cubic crystalline structure in solar cells

Polycrystalline thin films of AgSbS 2 of thickness 140 nm and crystalline structure matching that of the mineral cuboargyrite ( a  = 0.5652 nm) are obtained by heating chemically deposited thin films at 150–320 °C. These films are deposited at 40 °C from a solution mixture containing antimony‐thiosulfate complex and Ag‐nitrate at a mole‐fraction Ag/(Ag+Sb) of 0.31. The as‐deposited films are progressively transformed to cubic‐AgSbS 2 , with the fraction of crystalline matter at 3.7% after heating at 150 °C and 98% at 280 °C. The crystalline grain diameter is limited to 8–11 nm. The amorphous film has an optical band gap ( E g ) of 2.03 eV and the film heated at 320 °C has an E g of 1.79 eV. The crystalline films are photoconductive; with electrical conductivity of 10 −5  Ω −1  cm −1 under an intensity of illumination, 1000 W m −2 (tungsten‐halogen). The mobility–lifetime product of the material is 7.5 × 10 −7  cm 2  V −1 . A solar cell, SnO 2 :F/CdS/AgSbS 2 (420 nm)/C, has open circuit voltage, 0.615 V; short‐circuit current density, 1.67 mA cm −2 ; and conversion efficiency, 0.57% for air‐mass 1.5 global solar radiation. Estimate for the maximum photo‐generated current density for cubic‐AgSbS 2 is 16 mA cm −2 ; hence a supplementary absorber is recommended for future development of the solar cell.