The Amorphous/Crystalline Silicon Interface Research of HIT Solar Cells by Simulation

Abstract

In this paper, we have focused on the influence of interface state density and band offsets on the performance of HIT solar cells by simulation. The interface state density Dithave negative influence on the open-circuit voltage VOC, fill factor FF and the short circuit current JSC, beyond different Ditrespectively. VOCdecreases monotonically with increasing Ditonly when Ditis greater than 1010cm-2, and for FF and JSCDitis 1012cm-2, 1013cm-2, respectively. Observed reduction in VOC(Ditis from 1×1010cm-2to 5×1013cm-2) may be due to the enhanced recombination possibility, which diminishes the difference in quasi Fermi energies from 0.8 eV to 0.46 eV. Reduction of JSC(Ditis from 1×1013cm-2to 5×1013cm-2) is connected with the carrier recombination rate that is heightened from 2.43×1024cm-3/s to 3.1×1026cm-3/s, which is markedly by two orders of magnitude. In addition, our research results demonstrate that by increasing the conduction band offset EC(from 0.09eV to 0.15 eV), the VOCcould be increased by 15.9 mV, while the performance of HIT solar cells is not affected by the valence band offset EV. The increase of ECresults in the rising of Vbiand thus improves VOC. It is worth mention that, the recombination potential VRecould be decreased from 232 meV to 208 meV by the increase of EC(from 0.09eV to 0.15eV) and thus is favorable to VOC. Consequently, when the interface state density is less than 1010cm-2and the conduction band offset reaches 0.15eV, we can optimize the performance of HIT solar cells to achieve 24.95% efficiency.