Droplet-Merging and Dissolution-Induced Intermediate State Strategy Enabled Efficiency > 17.5% for the Printed...

Molecular pre-aggregation behavior plays a critical role in the morphology of organic films and the device performance of organic solar cells (OSCs). In the high-boiling-point solvent system, the relatively slow drying crystallization kinetics impacted the solution-state molecular pre-aggregation control, complicating the films crystallization regulation. In this work, a novel approach to regulate the pre-aggregation characteristics of the thin films was developed by constructing a droplet-merging and dissolution-induced intermediate state during inkjet printing (IJP). During this process, three key parameters, the printing temperature, droplet space, and additives, were identified to be critical for the intermediate state formation. This method created an intermediate aggregation state that finally enhanced the crystallization and molecular orientations in films printed from ortho-dichlorobenzene, overcoming the slow kinetics challenge. Consequently, IJP OSCs achieved a record power conversion efficiency of 17.57% through this droplet-merging and dissolution-induced intermediate strategy.