Towards sustainable and safe-by-design energy solutions: Citric acid/perylene derived carbon dots as cathode interfacial layer in organic solar cells

In this study, carbon dots (CDs) synthesized from citric acid/perylene derived from agricultural or biodiesel waste by following the paradigm of circular chemistry, are used as a cathode interlayer (CIL) in non fullerenic organic solar cells (OSCs). The integration of CDs in OSCs not only reduces the work function of the cathode metal, but also enhances the extraction of charge carriers, while simultaneously minimizing carrier recombination. Comparative analysis between CD-incorporating OSCs and those featuring commercial aliphatic amine-functionalized perylene-diimide (PDINN) as CIL reveals that while both exhibit similar photovoltaic parameters, a notable improvement is observed when utilizing their unprecedented combination in a CD/PDINN bilayer CIL. Consequently, the maximum power conversion efficiency of commercial PBDB-T/ITIC OSC reaches 9.14 %, sustained under constant AM1.5 G illumination for at least 90 min. These findings suggest that CDs are promising candidates for stable and efficient cathode interlayers, even though they are deposited from water solution, underscoring their potential in advancing sustainable and safe-by-design solar cell technologies.