Elimination of Drying‐Dependent Component Deviation Using a Composite Solvent Strategy Enables High‐Performance Inkjet‐Printed Organic Solar Cells with Efficiency Approaching 16%

Abstract Inkjet printing (IJP) is a roll‐to‐roll (R2R) compatible fabrication method for large‐area organic solar cells (OSCs). Unlike the coating process, the films are formed through droplet leveling and merging during IJP, and the pre‐deposited droplets are partly dissolved by the subsequent droplets. Such a process yields undesired printing pattern lines, especially in large‐area printed films. This study reveals that such a temperature‐dependent “drying lines‐related” phase separation morphology has caused component variation in the organic blend films, which leads to an obvious inhomogeneity of photocurrent in the printed OSCs. Such a phenomenon is attributed to the solubility difference between organic donor and acceptor molecules in the main printing solvent. A composite solvent strategy of ortho‐dichlorobenzene (oDCB)/trimethylbenzene (TMB) and tetralin (THN) is developed to solve this problem. The introduction of THN suppresses the formation of printing drying lines during high‐temperature printing due to the preferential miscibility of acceptor in THN, leading to the efficiency improvement to 13.96% and 15.78% for the binary and ternary devices. In addition, the 1 cm 2 device with a disruptive pattern gives an efficiency of 12.80% and a certificated efficiency of 12.18%.