Abstract
In this study we have developed a new calculation procedure for the crystal total free energy, which includes the total defect formation enthalpy and the configurational entropy. We have combined the defect physics, which studies about the first principles calculations of the defect formation energies and the defect levels, and the defect chemistry, which studies about the defect concentrations and the charge neutrality equation, to explore the relationships between the opto-electrical properties (e.g. absorption coefficients, reflectivities, diffusion coefficients and carrier lifetimes) and the atomic compositions of non-stoichiometric photovoltaic materials CuInSe2, CuGaSe2, ZnO and ZnO:Al. We found that our simulation results explain the other group’s experimental results well, and that this procedure is useful not only to the calculations of the equilibrium state properties but also the non-equilibrium state properties (through the combination with a numerical device simulator). In addition, we have also developed a full-functional (I-V, C-V, indoor and outdoor applications) analytical 1D heterojunction solar cell simulator, and then applied the calculated opto-electrical parameters to the solar cell efficiency simulations. This job set a basis for our future development of a full-numerical solar cell simulator. Furthermore, we have studied the controllability of the thin film compositions of our physical vapor deposition systems (radio frequency magnetron (reactive) sputter and rapid thermal processor) and have correlated the process parameters to the material/device structure parameters. This is crucial for the development of the large area photovoltaic industry.