Recent Progress and Prospects in Organic Solar Cells Processed with Non-Halogenated Solvents

Against the backdrop of the global energy transition and sustainable development initiatives, organic solar cells (OSCs) have emerged as a promising clean energy technology that requires an urgent transition to environmentally benign manufacturing processes. From environmental, health, and safety perspectives coupled with industrial scalability requirements, there exists a critical need to replace hazardous halogenated solvents, such as chloroform (CF), which are conventionally employed in high-performance OSC fabrication, with more environmentally friendly non-halogenated alternatives. Current challenges in room-temperature processing using non-halogenated solvents primarily stem from three interrelated factors: inadequate solubility of photoactive materials, excessive molecular aggregation, and disordered stacking morphology, all of which collectively degrade device performance. This review systematically examines the processing of non-halogenated solvents for OSCs in the following three critical aspects: first, this review focuses on the classification and selection of processing solvents and the impact on the morphology of the active layer. Subsequently, recent progress in photoactive material design (particularly small molecule acceptors) and device engineering strategies that enhance OSC processability in non-halogenated solvents is categorized and analyzed. Finally, the challenges for the OSCs toward more environmentally friendly processing and prospects for future applications are proposed.