Above 10% efficiency flexible inkjet-printed kesterite solar cells

Cu2ZnSn(S,Se)4 (CZTSSe or kesterite) is an emerging inorganic light absorber with a bandgap of 1.0–1.5 eV, ideal for efficient solar spectrum harvesting. This material can be grown on both rigid and flexible substrates, standing as one of the most promising candidates for Integrated Photovoltaics. Solution-based methods are currently the best choice for CZTSSe synthesis, relying on the deposition of multiple layers. The most widely used techniques are blade coating, spray pyrolysis, dip coating, and spin coating, with the latter achieving the highest efficiencies. However, this technology’s small-area limitations and large precursor waste still hinder the kesterite solar cells’ scalability. In contrast, drop-on-demand inkjet printing is a promising and industrially appealing solution-based technique suitable for processing large areas. To date, it has been tested in a few cases, yielding encouraging results with rigid solar devices; however, it has never been used to fabricate flexible CZTSSe solar cells. In this work, we report on the first-time realization of inkjet-printed flexible kesterite solar cells. The resulting devices exhibit an efficiency enhancement over our spin-coated references, driven by improved film crystallinity, reduced shunting, and enhanced fill factor. The inkjet-printed flexible champion device achieved an efficiency of 10.4%, outperforming our spin-coated reference counterpart. Structural, morphological, and optoelectronic analyses confirm the superior quality of the inkjet-deposited absorber. This scalable, solution-based approach establishes a pathway for the roll-to-roll fabrication of earth-abundant, lightweight kesterite photovoltaics for next-generation, integrated, and flexible photovoltaic applications, a key factor for the advancement of kesterite materials in the photovoltaic sector.