A NOVEL CADMIUM FREE BUFFER LAYER FOR CU(IN,GA)SE-2 BASED SOLAR-CELLS

Solar cells based on Cu(In,Ga)Se, were prepared replacing the ''standa rd buffer layer'' CdS with a In-x(OH,S)(y) thin film. The film is depo sited in a chemical bath (CBD) process using an aqueous solution conta ining InCl3 and thioacetamide. X-ray photoemission spectroscopy measur ements were performed in order to characterize the growth kinetics and the chemical composition. The influence of different concentrations o f InCl3 and thioacetamide in the solution on the electrical properties of the solar cells was studied by measuring the j-V characteristics a nd the spectral quantum efficiencies. Capacitance-voltage (C-V) measur ements indicate that the high V-alpha values of devices with the novel buffer layer are correlated with narrower space charge widths and hig her effective carrier concentrations in the absorber materials. The ac hieved conversion efficiency of 15.7% (active area) using the cadmium free In-x(OH,S)(y) buffer demonstrates the potential of this process a s an alternative to the standard chemical bath deposition of CdS.