Performance Improvement in Solution Based CuInS2 Solar Cell by Optimizing the Absorber Layer Deposition

In this research, solution based CuInS2 (CIS) thin film solar cell with glass/FTO/TiO2/In2S3/CIS/Carbon structure fabricated from CIS nanoparticle ink. The CIS absorber layer, which is the most important part of the cell, is deposited by drop casting CIS nanoparticle ink dispersed in DMF followed by heat treatment to 250 °C. X-Ray diffraction (XRD) of the absorber layer shows respectable crystallinity with pure chalcopyrite phase. UV-Vis spectrum of the CIS nanoparticle ink confirms high optical absorption in visible wavelengths. Micrographs of the CIS layer show obvious voids and discontinuity in the layer. The discontinuity in the absorber layer has direct impact on the cell performance. In the absence of a packed absorber layer, the charge carriers’ transfer reduces significantly. The absorber layer’s morphology has been improved by controlling the vapor pressure during heat treatment. As a result, the absorber layer changes to a more packed structure with fewer voids. Optimization of the absorber layer deposition leads to and efficiency is enhancement of 136 % from 2.2 % to 5.2 %.