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Textured back reflector (BR) plays an important role to achieve light trapping in amorphous silicon solar cell. We investigated n–i–p type amorphous silicon solar cell, fabricated on textured BR. The solar cells showed improvement in current density and red response of the external quantum efficiency (EQE) spectra. We used simplified ray diagram along with double reflection model to analyze the EQE because the pyramidal surface texture had apparently little or no periodicity in its surface distribution. The Beer–Lambert's exponential absorption relation was used to estimate photo‐current generation. Experimental results and theoretical analysis indicates that the trapping of unabsorbed light within the cell contributes to enhanced red response to the EQE. A further enhancement in current density and EQE was obtained by double texturing the BR. It appears that in addition to enhanced light trapping, a significant reduction in parasitic absorption of light may also contribute to the improvement in cell performance. The double texturing of the BR led to an increase in surface roughness of the cell, that further helps in the light trapping by introducing increased randomness of the light that is transmitted into the cell.

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A modified emitter, of stacked two layer structure, was investigated for high-efficiency amorphous/crystalline silicon heterojunction (HJ) solar cells. Surface area of the cells was 181.5 cm2. The emitter was designed to achieve a high open circuit voltage (Voc) and fill factor (FF). When doping of the emitter layer was increased, it was observed that the silicon dihydride related structural defects within the films increased, and the Voc of the HJ cell decreased. On the other hand, while the doping concentration of the emitter was reduced the FF of the cell reduced. Therefore, a combination of a high conductivity and low defects of a single emitter layer appears difficult to obtain, yet becomes necessary to improve the cell performance. So, we investigated a stacked-emitter with low-doped/high-doped double layer structure. A low-doped emitter with reduced defect density was deposited over the intrinsic hydrogenated amorphous silicon passivation layer, while the high-doped emitter with high conductivity was deposited over the low-doped emitter. The effects of doping and defect density of the emitter, on the device performance, were elucidated by using computer simulation and an optimized device structure was formulated. The simulation was performed with the help of Automat for the Simulation of Heterostructures simulation software. Finally, based on the simulation results, amorphous/crystalline heterojunction silicon solar cells were optimized by reducing density of defect states in the stacked-emitter structure and we obtained 725 mV, 77.41%, and 19.0% as the open-circuit voltage, fill factor, and photo-voltaic conversion efficiency of the device, respectively.