Selectively Modulating Componential Morphologies of Bulk Heterojunction Organic Solar Cells.

Achieving precise control over the nanoscale morphology of bulk heterojunction (BHJ) films presents a significant challenge for the conventional post-treatments employed in organic solar cells (OSCs). In this study, we have developed near-infrared photon-assisted annealing (NPA) strategy for fabricating high-performance OSCs under mild processing conditions. It was revealed a top NIR light illumination, together with the bottom heating, enabled the selective tuning of the molecular arrangement and assembly of narrow bandgap acceptors in polymer networks to achieve optimal morphologies, as well as acceptor-rich top surface of active layers. The derived OSCs exhibit a remarkable power conversion efficiency (PCE) of 19.25%, representing one of the highest PCEs for the reported binary OSCs so far. Moreover, via NPA strategy, we have succeeded in accessing top-illuminated flexible OSCs using thermolabile polyethylene terephthalate (PET) from mineral water bottles, displaying excellent mechanical stabilities. Overall, this work would hold potentials to develop organic solar cells under mild processing with various substrates. This article is protected by copyright. All rights reserved.