Optical and electrical modeling of CZTSSe based thin-film solar cells

Abstract

This research utilized an optical and electrical model to examine the impact of optical and recombination losses on the short circuit current density, J sc , and conversion efficiency of thin-film solar cells based on n-CdS/p-CZTSSe with ITO frontal charge-collecting contacts. By analyzing the optical properties of the components, we were able to calculate the amount of light that was lost as a result of absorption in the ITO and CdS layers and as a result of reflection at all interfaces. The impact of using antireflection coating on the optical losses was studied. Recombination losses were calculated quantitatively by varying the CZTSSe thickness and depletion area width. It was found that the antireflection layer reduced the optical losses up to 20%. The minimum value of the recombination losses is about 11% of what is observed at a width more than 1 μm, and that the width of the depletion layer has a significant impact in the value of J sc . Most of the incoming photons were absorbed by a layer of CZTSSe 3–4 μm thick. At these thicknesses, the recombination losses were considered low and recorded 16%. At reasonable values for the parameters employed, the efficiency of 14% is achievable.