Organic Solar Cells Processed with Terpene Solvent Under Ambient Condition— Impact of Processing Conditions on In Situ UV-Vis Spectroscopy, Morphology and Performance

Organic electronics have prompted increasing efforts to develop greener and safer processing solvents as alternatives to conventional solvents, which pose considerable environmental and health concerns. In this work, we present high-performance organic solar cells (OSCs) processed using eucalyptol (Eu), a single terpene-based solvent with negligible toxicity and minimal environmental hazards. Remarkably, the OSCs achieve a record-breaking power conversion efficiency (PCE) of 15.1% without the use of any additives—a significant milestone compared to previously reported PCEs of 0.1–3.0% for OSCs processed with single terpenes.
This remarkable performance is attributed to two key advancements: (1) the molecular engineering of a novel small-molecule acceptor, MYBO, with optimized side chains that balance solubility and excellent optoelectronic properties, and (2) the development of a refined film formation technique that independently controls the aggregation kinetics of the polymer donor and MYBO. This approach enables the formation of well-defined MYBO crystallites embedded within an interconnected polymer fibrillar network. Moreover, all solution processing is conducted in ambient air, eliminating the need for glove-box condition and reinforcing the eco-friendly nature of this approach.
The resulting devices exhibit outstanding operational stability, retaining over 92% of their initial PCE after 2300 hours of exposure to air without encapsulation. This study provides critical insights into material design and processing strategies for achieving high-performance, environmentally sustainable OSCs, offering a significant step forward in the field of green organic electronics.