ABSORBER LAYER THICKNESS OPTIMIZATION OF a-Si:H/a-SiGe:H/μc-Si SOLAR CELL WITH INTERMEDIATE ZnO LAYER

摘要

In this paper, the major issue of current matching in triple-junction silicon solar cell has been addressed with i-layer thickness optimization at Maximum-Power-Point(MPP) using simulation and scripting. A performance of triple-junction(a-Si/a-SiGe/μc-Si) silicon solar cell has been analyzed with various i-layer thicknesses of sub-cells. The use of existing models developed for single-junction solar cell, are extended for multi-junction solar cell. In modeling of multi-junction cell, a common model for top and middle sub-cell and another model for bottom sub-cell are used. The cell is modeled on MATLAB~? platform. The primary objective of this work is to obtain the optimized sub-cell thicknesses operating at or near MPP. To estimate the optical performance improvement in cell performance and reduction in light induced degradation effect in top a-Si sub-cell, an intermediate reflector layer(40 nm) is incorporated between top a-Si sub-cell and middle a-SiGe sub-cell. The sub-cell’s current expressions are solved using numerical technique. The optimized thicknesses are obtained for top a-Si i-layer with and without ZnO Intermediate Reflector(ZIR) layer at MPP are 120 nm and 140 nm respectively. The P_(mpp)has improved from 11.51mW/cm~2 to 11.63mW/cm~2 and FF from 72% to 77% for without and with ZIR layer insertion respectively.