Circular Nanocavity in Ultrathin c-Si Solar Cell for Efficient Light Absorption
In this work, the effect of circular nanocavity on light trapping in a c-Si solar cell was studied by finite difference time domain (FDTD) simulation. The structure of the solar cell was considered to be Si3N4/c-Si/Ag, where the Ag layer was pattered and conformal growth of Si and Si3N4 was considered. The absorption spectra in the thin Si layer were determined and found 40 times higher at the infrared region (beyond 800 nm). For qualitative analysis, the short-circuit current of the solar cell was determined computationally by AM 1.5G solar illumination and found to be 2.1 times higher in the case of nanocavity as that compared to un-patterned solar cell. The enhancement in absorption in the solar cell is attributed to the different plasmonic modes coupled in the thin c-Si layer. The incident angle-dependent study was performed to observe the effect on enhancement in wide-angle incidence. The thickness-dependent study confirms 2.1 to 1.75 times enhancement in short-circuit current in 100- to 250-nm-thick c-Si layer. Therefore, this observation suggests that this structure has good prospect in achieving high conversion efficiency while reducing the device cost.
KeywordsCircular nanocavity c-Si Thin film solar cell Plasmonic SPP Short-circuit current
The author would like to thank Prof. S. P. Dttagupta and Prof. S. Ganguly, Department of Electrical Engineering, IIT Bombay, for accessing the CST microwave studio and Lumerical. The author is also thankful to Arnab Pattanayak, CRNTS, IIT Bombay, for the fruitful discussion in the result and analysis.
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