High-speed doctor-blading PM6:L8-BO organic solar cells from non-halogenated green solvent with a module efficiency of 16.07%

Highly efficient organic solar cells (OSCs) are normally produced using the halogenated solvents chloroform or chlorobenzene, which present challenges for scalable manufacturing due to their toxicity, narrow processing window and low boiling point. Herein, we develop a novel high-speed doctor-blading technique that significantly reduces the required concentration, facilitating the use of eco-friendly, non-halogenated solvents as alternatives to chloroform or chlorobenzene. By utilizing two widely used high-boiling, non-halogenated green solvents—o-xylene (o-XY) and toluene (Tol) —in the fabrication of PM6: L8-BO, we achieve power conversion efficiencies (PCEs) of 18.20% and 17.36%, respectively. Additionally, a module fabricated with o-XY demonstrates a notable PCE of 16.07%. In-situ testing and morphological analysis reveal that the o-XY coating process extends the liquid-to-solid transition stage to 6 s, significantly longer than the 1.7 s observed with Tol processing. This prolonged transition phase is crucial for improving the crystallinity of the thin film, reducing defect-mediated recombination, and enhancing carrier mobility, which collectively contribute to superior PCEs.