Development of a comprehensive design tool for non-stoichiometric compound thin film solar cells: Calculations of the opto-electrical properties of multinary alloy and optimization of the cell performance

Based on our previously developed design methodologies which minimized the total free energy and the calculations of the defect/carrier concentrations and the carrier mobility of the non-stoichiometric CuInSe2, CuGaSe2, ZnO and ZnO:Al, good confirmation was obtained from our computed conductance of CuInSe2 with the measured data, in which the total energy calculation was modified by considering the configurational entropy, and solving the coupled total free energy function and the charge neutrality equation self-consistently. In addition, a method to calculate the opto-electrical properties of CuInxGa1−xSe2 alloy, which is the most popular absorber for high efficiency thin film solar cells, was also effectively developed. Furthermore, the above electrical parameters of the non-stoichiometric window/absorber layers were used to optimize the cell structure, and their performances were correlated with the published experimental results.