Efficient amorphous silicon solar cells : characterization, optimization, and optical loss analysis

Abstract

Hydrogenated amorphous silicon (a-Si:H) has been effectively utilized as photoactive and doped layers for quite a while in thin-film solar applications but its energy conversion efficiency is limited due to thinner absorbing layer and light degradation issue. To overcome such confinements, it is expected to adjust better comprehension of device structure, material properties, and qualities since a little enhancement in the photocurrent significantly impacts on the conversion efficiency. Herein, some numerical simulations were performed to characterize and optimize different configuration of amorphous silicon-based thin-film solar cells. For the optical simulation, two-dimensional finite-difference time-domain (FDTD) technique was used to analyze the superstrate (p-i-n) planar amorphous silicon solar cells. Besides, the front transparent contact layer was also inquired by using SnO2:F and ZnO:Al materials to improve the photon absorption in the photoactive layer. The cell was studied for open-circuit voltage, external quantum efficiency, and short-circuit current density, which are building blocks for solar cell conversion efficiency. The optical simulations permit investigating optical losses at the individual layers. The enhancement in both short-circuit current density and open-circuit voltage prompts accomplishing more prominent power conversion efficiency. A maximum short-circuit current density of 15.32 mA/cm2 and an energy conversion efficiency of 11.3% were obtained for the optically optimized cell which is the best in class amorphous solar cell.