Structural and photovoltaic properties of sputtered CIGS thin films: the effect of quaternary target stoichiometry

Abstract

Copper indium gallium selenide (CIGS) thin-film solar cells are a leading technology for next-generation photovoltaics due to their high absorption coefficients and tunable electronic properties. However, achieving optimal device performance via scalable methods like magnetron sputtering is critically dependent on precise stoichiometric control of the quaternary absorber layer, which remains a significant challenge. We fabricated CIGS thin films by sputtering from two distinct targets, one slightly Cu-poor and one Cu-rich, followed by a rapid thermal selenization process. We found that annealing at 500 degrees C for 30 minutes is optimal for producing highly crystalline films with minimal secondary phases. Devices fabricated using the Cu-poor target achieved a power conversion efficiency of 4.6%, with an open-circuit voltage (V-oc) of 412.5 mV and a short-circuit current density (J(sc)) of 19.14 mA/cm(2). Engineering the target stoichiometry is a crucial and direct strategy for simplifying the fabrication and enhancing the performance of sputtered CIGS photovoltaics.