Efficiency Analysis and Optimization of Light Trapping in Amorphous Silicon Heterojunction Solar Cell with Lumerical FDTD/DEVICE

Abstract

This study investigated the two-dimensional computer analysis of a tandem solar cell: c-Si/a-Si:H/µc-SiGe, with Lumerical FDTD/DEVICE 4.6. Optical characterization was performed in FDTD and then the total generation rate was transported into DEVICE for electrical characterization. Electrical characterization of the solar cell was carried out in DEVICE. In the first stage, a single junction solar cell was studied with both a-Si and µc-SiGe, respectively, as its absorbing layers. The thickness for both layers was kept the same. For the a-Si absorbing layer Jsc = 10.959 mA/cm2 , Voc = 696.97 mV, FF = 78.985%, and η = 6.033% were achieved. The efficiency for the µc-SiGe absorbing layer was improved up to η = 7.0667. In the second stage, with the implementing tandem design for the thin film solar cell as c-Si/a-Si:H/µc-SiGe; the Jsc = 16.4136 mA/cm2 ; Voc = 732.323 mV; FF = 81.9017%; and η = 9.84462% were recorded. Moreover, three different light trapping techniques were compared with the efficiencies of planner solar cell and with anti-light reflecting coatings (TIO2 and SI3N4). The efficiency is optimized with Checkerboard Light Trapping Design (QPEC), as η = 12.397%. The increase in efficiency is 20.5% as compared to the planer solar cell, 17.2% as compared to the Pyramidal Technique, and 15.42 % as compared to ITO and SI3N4. In the QPEC technique, the percent increase in efficiency is 9.2% as compared to the planer solar cell and 3.3% increase as compared to ITO and SI3N4. With Pyramidal Design, light trapping is increased to 4.1% as compared to the planer solar cell and 2.17% reduced as compared to ITO and SI3N4. The efficiencies for both ITO (TIO2) and SI3N4 antireflection coatings are noticed to be same as η = 10.4855%. By insertion of a buffer layer at the second interface from the top, the efficacy is improved up to η = 13.065%.