Sustainable eco-friendly printing of high-performance large-area organic photovoltaics via enhanced Laplace pressure gradient

The coffee-ring effect during the green-printed process remains a significant bottleneck hindering the scalable fabrication and practical deployment of organic photovoltaics. Here, a fluorinated rheology modifier 1H,1H,10H,10H-Perfluoro-1,10-decanediol is brought to fine-tune the rheological properties of the active layer solution and the shape of the printed gas/liquid confined zone. The Laplace pressure gradient generated by the rheology modifier along printing direction effectively suppresses the coffee-ring effect. This results in enabling the formation of highly uniform large-area active layer films. The gas/liquid confined zone is qualitatively and quantitatively analyzed to understand the function of the Laplace pressure gradient. Meanwhile, the clear fiber network active layer morphology with high crystallinity and moderate phase separation is obtained through the rheology modifier modulation of printing fluid dynamics. Therefore, based on PM6:BTP-eC9:L8-BO (o-xylene), small-area (0.04 cm²) devices achieve a power conversion efficiency of 20.49%. More importantly, scalable module (16.94 cm²) harvests a high efficiency of 17.85% with a nice efficiency retention rate of 87.1%. This study broadens the processing window and the range of potential applications for high-throughput green printing of large-area organic photovoltaics.