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 D_it have negative influence on the open-circuit voltage V_OC, fill factor FF and the short circuit current J_SC, beyond different D_it respectively. V_OC decreases monotonically with increasing D_it only when D_it is greater than 10¹⁰ cm^-2, and for FF and J_SC D_it is 10¹² cm^-2, 10¹³ cm^-2, respectively. Observed reduction in V_OC (D_it is from 1×10¹⁰ cm^-2 to 5×10¹³ cm^-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 J_SC (D_it is from 1×10¹³ cm^-2 to 5×10¹³ cm^-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 E_C (from 0.09eV to 0.15 eV), the V_OC could be increased by 15.9 mV, while the performance of HIT solar cells is not affected by the valence band offset E_V. The increase of E_C results in the rising of V_bi and thus improves V_OC. It is worth mention that, the recombination potential V_Re could be decreased from 232 meV to 208 meV by the increase of E_C (from 0.09eV to 0.15eV) and thus is favorable to V_OC. Consequently, when the interface state density is less than 10¹⁰ cm^-2 and the conduction band offset reaches 0.15eV, we can optimize the performance of HIT solar cells to achieve 24.95% efficiency.

• Periodical: Advanced Materials Research (Volume 773)
• Pages: 124-131
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.773.124
• Online since: September 2013
• Authors: Hao Li, Xiang Bo Zeng, Xiao Bing Xie, Ping Yang, Jing Yan Li, Xiao Dong Zhang, Qi Ming Wang
• Keywords: Band Offsets, Hit, Interface State Density

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