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%.