Role of interface layer in improving the efficiency of thin film silicon solar cell

Lower photonic conversion efficiency along with complexity of fabrication are the primary constrains for cost effective thin film solar cell production. In this work, a planar single junction structure of thin film solar cell made with two different active materials is studied, which can take care of the mentioned problems. The active materials were selected based on different parameters like band gap energy, contact potential, lattice mismatch and cost effectiveness. Simulation shows that optical absorption along with photonic conversion efficiency varies due to change in position, thickness and doping concentration of active material and so these parameters are optimized accordingly. Here an interface layer of Gallium Arsenide (GaAs) is added to the thin film Silicon (Si) layer. Our optimized Si-GaAs based thin film solar cell yields a short circuit current density of 27.51 mA/cm2 with conversion efficiency of 13.71% having a fill factor of 0.81 under AM1.5G for a typical thin film solar cell of total thickness 2 µm out of which 80% is crystalline Silicon (1.6 µm thick) and 20% is Gallium arsenide (0.4 µm thick). Thus, a simple structure with improved conversion efficiency is proposed.