Water-Based Inks for Inkjet-Printed Cu(InGa)(SSe)2 Thin Film Solar Cells with a Power Conversion Efficiency of 15%

Abstract

As a highly promising on-demand manufacturing technology, inkjet printing offers a viable pathway for the cost-effective and large-scale production of thin-film solar cells.However, inkjet-printed Cu(InGa)(SSe)2 (CIGSSe) thin film solar cells typically exhibit lower power conversion efficiencies (PCEs) than those spin-coated counterparts.Moreover, the PCEs of CIGSSe solar cells fabricated by eco-friendly water-based precursor solutions have remained stagnant for many years. To address these challenges, this work introduces a novel water-based Cu(In,Ga)S2 (CIGS) precursor ink with a tailored water/ethanol ratio, enabling the room-temperature and air-processed deposition of uniform and continuous CIGSSe films via inkjet printing. The optimized ink demonstrates excellent air stability, suitable viscosity, and favorable wettability, as systematically investigated through varying water/ethanol ratios. By optimizing the ink formulation, we achieved an encouraging PCE of 15.0% for water-based CIGSSe solar cells. Furthermore, this approach significantly enhances raw material utilization, thereby reducing material costs while maintaining environmental sustainability. Our findings pave the way for scalable and high-performance CIGSSe photovoltaics using an eco-friendly inkjet printing process.