Bandgap optimization of absorber layers in amorphous silicon single and multijunction junction solar cells

Single and multijunction amorphous silicon thin film solar cells have been investigated here by the Analysis of Microelectronic and Photonic Structures (AMPS 1D) simulator in regard to overall performance. The photovoltaic characteristics have been observed by changing the bandgap of the absorber layers, variation of light intensity and the effect of operating temperature for single and multijunction devices. The absorber layer a-SiO:H in single junction cell has shown better efficiency trend within the bandgap range of 1.8-2.2 eV and the highest efficiency of 17.67% is achieved at 2 eV. Moreover, efficiency of 17.95% has been found at 10 suns. The second absorber layer a-SiC:H in double junction cell shows the highest efficiency of 19.04% at 1.9 eV. In contrast, the maximum efficiency of 20.42% has been found for the bandgap of 1.8 eV in a-Si:H as absorber layer of the bottom cell in triple junction configuration. For double and triple junctions, the efficiency increased to 21.94% and 25.58% at 30 and 100 suns, respectively. The temperature gradients for single, double and triple junction are found to be -0.17%/₀C, -0.20%/⁰C and - 0.28%/⁰C, respectively.