Layer-by-Layer Processed Organic Photovoltaic Cells Using Slot-Die-Coating Methods and Non-halogenated Solvents under Ambient Conditions with PCE of 10%

Abstract

Laboratory-controlled conditions, spin-coating method, and non-ecofriendly halogenated solvents that have been employed for higher-performance organic solar cells (OSCs) are not compatible with large-scaled, roll-to-roll (R2R) manufacturing in ambient conditions. Slot-die coating is a viable upscaling method, but the investigation of slot-die-coated OSCs is still rare, especially OSCs with all functional layers deposited with non-halogenated solvents in air. Herein, all slot-die coated devices are successfully manufactured by sequentially slot-die coating the hole transport layer (PEDOT:PSS), the photoactive layers (PM6 and BTP-4F-12 (Y6-C12)), and the electron transport layer (PFN-Br). Because of solubility variation of photoactive components in non-halogenated solvents (o-Xylene and 2-methyltetrahydrofuran (2-MeTHF)), two bilayer-processed photoactive films have been obtained via different solvent combinations (o-Xylene/o-Xylene for PM6 (o-Xylene)/Y6C12 (o-Xylene) and o-Xylene/2-MeTHF for PM6 (o-Xylene)/Y6C12 (2-MeTHF)). Different morphologies of bilayer-processed photoactive films influence exciton dissociation and charge extraction properties of corresponding devices. Finally, the device hosting o-Xylene/o-Xylene processed photoactive film has a superior efficiency (10.6%) than the o-Xylene/2-MeTHF processed photoactive film-based device (7.2%). Differently from device efficiency, the device based on o-Xylene/2-MeTHF processed photoactive film exhibits the preferable storage stability.