Front Surface Glass Texturization for Improved Performance of Amorphous Silicon Solar Cell

Abstract

Texturization of the front glass of superstrate type single junction amorphous silicon solar cells has been carried out in order to achieve the dual role of reducing reflectivity as well as increasing the angular scattering of light leading to more light trapping. Glass texturization has been carried out chemically using an aqueous solution of HF. To achieve a controlled etch rate (a) KOH or (b) AgNO₃ is added to the aqueous solution of HF for selectively masking the front surface of glass with K₂SiF₆ or Ag nano-islands respectively. It may be noted that such texturing also increases the parasitic absorption due to larger light paths in the absorbing thin conducting oxide layer present in such superstrate type single junction amorphous silicon solar cells. Thus, an optimization is necessary for the top glass surface texturing for enhancement of the efficiency of the solar cell. It is found that the reflectivity reduces by about 3 % in both the cases from the reference value of about 9.5 %. Moreover, it is seen that the diffused transmission characteristics of the textured glass surface increases significantly (~30 %) which is expected to improve the overall short circuit current and efficiency of the solar cell. The present method of texturing the glass superstrate for anti reflection and light trapping in thin-film solar cells appears to be a promising method amenable for large scale applications.