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Organic-inorganic hybrid tandem solar cells attract a considerable amount of attention due to their potential for realizing high efficiency photovoltaic devices at a low cost. Here, highly efficient triple-junction (TJ) hybrid tandem solar cells consisting of a double-junction (DJ) amorphous silicon (a-Si) cell and an organic photovoltaic (OPV) rear cell were developed. In order to design the TJ device in a logical manner, a simulation was carried out based on optical absorption and internal quantum efficiency. In the TJ architecture, the high-energy photons were utilized in a more efficient way than in the previously reported a-Si/OPV DJ devices, leading to a significant improvement in the overall efficiency by means of a voltage gain. The interface engineering such as tin-doped In2O3 deposition as an interlayer and its UV-ozone treatment resulted in the further improvement in the performance of the TJ solar cells. As a result, a power conversion efficiency of 7.81% was achieved with an open-circuit voltage of 2.35 V. The wavelength-resolved absorption profile provides deeper insight into the detailed optical response of the TJ hybrid solar cells.

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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.