Fabrication of low-cost n-Sb₂S₃/p-Ge heterojunction solar cells

A novel method to fabricate low-cost n-Sb₂S₃/p-Ge heterojunction solar cells by chemical deposition is reported. It has been observed that, in the case of n-Sb₂S₃ films chemically deposited with silicotungstic acid on (111) oriented single-crystalline p-Ge and annealed, the heterojunction solar cell properties are considerably improved. Dark current-voltage (I-V) measurements (in the range 298-380 K) on n-Sb₂S₃/p-Ge and siligotuxngstic-acid-deposited n-Sb₂S₃/p-Ge heterojunction devices showed an increase in barrier height ( phi _b) from 0.65 to 0.89 eV, a decrease in ideality factor (n) from 2.21 to 1.38 and in reverse saturation current density (J₀) from 6.27*10^-7 to 3.8*10^-9 A cm^-2. Capacitance-voltage (C-V) studies at 1 MHz showed higher values of phi _b for the improved device. Under AM1 (air mass 1) illumination, the improved junction showed an efficiency ( eta ) of about 7.3% without any antireflection coating whereas the n-Sb₂S₃ films deposited without silicotungstic acid on p-Ge showed eta approximately=2.4%.