High open-circuit voltage of ternary Cu2GeS3 thin film solar cells from combustion synthesized Cu-Ge alloy

•Cu2GeS3 is creatively synthesized from Gu-Ge alloy prepared by combustion method.•The optical band gap of Cu2GeS3 is determined to be 1.5 eV measured by UV-Vis.•The Cu2GeS3 has a proper carrier concentration of 1016 cm−3 lower than Cu2SnS3.•2.67% efficiency Cu2GeS3 solar cell is obtained with a large Voc of 592 mV.

Ternary chalcogenide semiconductor copper germanium sulfide (Cu2GeS3) composed of earth-abundant and non-toxic elements is considered to be a suitable light harvesting material for photovoltaics. In this study, Cu2GeS3 thin film solar cells are creatively fabricated based on combustion method. XRD and Raman analyses reveal that the combustion synthesized product is composed of Cu-Ge alloy rather than metal oxides. The structural, morphological, optical and electrical properties of CGS films are analyzed in detail. The best power conversion efficiency of Cu2GeS3 thin film solar cell achieve 2.67% with a high open-circuit voltage of 592 mV. The experiment results reveal that the p-type semiconductor Cu2GeS3 is an extremely promising light harvesting material for photovoltaics due to its suitable band gap and carrier concentration.