Morphologically Controlled Efficient Air-Processed Organic Solar Cells from Halogen-Free Solvent System

Abstract

Power conversion efficiencies (PCEs) of glove-box (GB) processed, two-component, single-junction organic solar cells (OSCs) have recently exceeded 18%. However, their mass-scale manufacture using roll-to-roll (R2R) coating techniques is impracticable if they must be fabricated in an air-free environment. From a commercialization perspective, efficient air-processed OSCs are of much greater interest than GB-processed devices since the vast majority of R2R-manufacturing infrastructure is designed to operate in the air. Herein, it is reported that controlling the crystallinity of non-fullerene acceptors plays a key role in determining the properties of blend films. Notably, Y6-hu (a Y6-derivative) is shown to exhibits a higher degree of crystallinity when processed in air. Air-processed OSCs show an outstanding PCE of 17.38%, which, to the best of the authors’ knowledge, is the highest PCE yet reported for two-component-based OSCs processed in air using halogen-free solvents. Moreover, opaque large-area OSC sub-modules with PCEs of 12.44%, and red-green-blue colored semi-transparent OSC sub-modules with PCEs of >10% are demonstrated. By understanding how morphological features relate to the charge-generation dynamics of air-processed OSCs, a new window is opened for the fabrication of efficient and stable air-processable organic electronics.