Simulated solar cell device of CuGaSe2 by using CdS, ZnS and ZnSe buffer layers

We have performed ab-initio calculations for the structural, electronic, optical, elastic and thermal properties of the copper gallium chalcopyrite (CuGaSe2). The Full Potential Linearized Augmented Plane Wave (FP-LAPW) method is used to find the equilibrium structural parameters and to compute the full elastic tensors. We have reported electronic and optical properties with the recently developed density functional of Tran and Blaha. Furthermore, optical features such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients, optical conductivities, are calculated for photon energies up to 30 eV. The thermodynamical properties such as thermal expansion, heat capacity, Debye temperature, entropy and Grüneisen parameter, bulk modulus and hardness are calculated employing the quasi-harmonic Debye model at different temperatures (0–1200 K) and pressures (0–8 GPa) and the silent results are interpreted. To check the potentiality of CuGaSe2 as future solar cell material, device modeling and simulation studies have been carried out with a variety of buffer layers over CuGaSe2 absorption layer. The band diagram and J/V curves are analyzed and device performance parameters i.e. efficiency, open circuit voltage, short circuit current, quantum efficiency are calculated for CdS, ZnS and ZnSe buffer layers. Simulation results for CuGaSe2 thin layer solar cell show the maximum efficiency (15.8%) with ZnSe as the buffer layer. Most of the investigated parameters are reported for the first time.