Fabrication of CIGS thin film absorber by laser treatment of pre-deposited nano-ink precursor layer

A process to prepare Copper Indium Gallium Selenide (CIGS) absorber thin films by laser treatment of pre-deposited nano-inks has been investigated. Two approaches were followed, one using an ink of CIGS nanoparticles and other employing an ink comprising a mixture of a CIG metallic alloy and Se nanoparticles. Laser post treatment of the film applied with the CIGS ink was found to retain the chalcopyrite structure following melting and recrystallization, with no additional phases being generated during the process. Single-phase, highly crystalline CIGS thin films were also found to result from the ink made of CuIn0.7Ga0.3 and Se nanoparticles precursor following laser treatment. The CuIn0.7Ga0.3Se2 thin films obtained in both cases were consistent with the initial constitution of the precursor materials used in terms of the Ga/(Ga+In) ratio. The prepared films were comprehensively characterized using XRD, SEM-EDS and XRF. Results reveal that the above non-vacuum approach obviating the need for a selenization step is simple, quick and expected to have a large impact on the overall process economics for fabrication of CIGS thin film solar cells.