Optical Studies of Cadmium Telluride based Solar Cell using Photonic Crystal as a back Reflector

Abstract

In this paper cadmium telluride based, thin-film solar cell design using a 2D Photonic Crystal structure is proposed. CdTe technology is considered as having the best cost to efficiency ratio for the solar cells. A theoretical optical study and active layer thickness optimization has been presented using photonic crystal as a light-trapping structure placed at the back of the active layer. To reduce the cost of solar cell the active layer thickness is required to be kept small (~0.7 microns), but this results in weak absorption of incident spectrum. It is observed that these periodic structures help to enhance the absorption within the cell by enhancing the virtual thickness for high wavelength photons without letting the physical thickness of the active layer to increase. These structures result in improved scattering and coupling of incident photons. The proposed design has achieved the short circuit current of 29.25 mA/cm² at AM 1.5 is achieved. Here all the parameters are optimized using rigorous coupled-wave analysis.