A universal roll-to-roll slot-die coating approach towards high-efficiency organic photovoltaics

This work develops a combinational use of solvent additive and in-line drying oven on the flexible organic photovoltaics to improve large-area roll-to-roll (R2R) slot-die coating process. Herein, addition of 1,8-diiodooctane (DIO) in the photoactive layer is conducted to yield a performance of 3.05% based on the blending of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C-61-butyric acid methyl ester (PC61BM), and a very promising device performance of 7.32% based on the blending of poly[[4,8-bis[(2-ethylhexyl)oxy] benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl C-71-butyric acid methyl ester (PC71BM). Based on this R2R slot-die coating approach for various polymers, we demonstrate the high-performance result with respect to the up-scaling from small high-PCE cell to large-area module. This present study provides a route for fabricating a low-cost, large-area, and environmental-friendly flexible organic photovoltaics.