Optimization of a-Si Thin-Film Solar-Cell Performance with Passivation and c-Si Cap Layer

A modified design of the a-Si thin-film solar cell (TFSC) is presented. The c-Si cap layer is introduced to increase the photon absorption and hence the enhanced photo carriers increase the overall short-circuit current. Whereas, the highly doped a-Si passivation layer reduces the minority carrier flow and recombination at the rear side of the cell, and therefore the passivation layer is used to improve the open-circuit voltage ( V oc ). The performance optimization and investigation of the cell characteristic is executed using the numerical simulation methodology. To further enhance the cell efficiency, the thickness and doping concentration of the c-Si cap and a-Si passivation layer are optimized. The improvement in absorption and passivation quality of the cell leads to the enhancement of 10.54% in short-circuit current density and 71.51% improvement in the V oc , respectively. The designed a-Si TFSC absorbs the incoming solar spectrum from 300 to 850nm of wavelength and rest of the spectrum is transmitted. The external and internal quantum efficiency of the cell is well over 95% . The optimized efficiency of 15.33% is obtained for the designed cap layered a-Si passivated cell in AM1.5 G environment using ray-tracing methodology.