Morphology Evolution via a Generic Solvent Additive Concept Enables Large-Area All-Polymer Solar Cells with Negligible PCE Loss

Small-area all-polymer solar cells (all-PSCs) have obtained excellent power conversion efficiency (PCE) through smart design of materials and advanced device fabrication. Nevertheless, commercialization of all-PSCs requires the urgent development of large-area all-PSCs processing techniques compatible with roll-to-roll processing. Generally, the PCE of all-PSCs drops sharply with the increased device area, which is the biggest obstacle for fabrication of large-area all-PSCs toward commercialization. Morphology modulation of bulk heterojunction (BHJ) film may be an effective strategy for fabrication of large-area all-PSCs. In this work, a solvent additive 1,8-diiodooctane (DIO) is introduced to regulate the charge transport, molecular orientation, and BHJ film morphology of all-PSCs. As the device area of all-PSCs expands from 0.04 to 0.5 cm(2), the PCE of the device without DIO reduces by 14.8%, while that of the device with DIO only reduces by 3.3%. To the best of the authors' knowledge, this is the lowest PCE attenuation value achieved for 0.5-1 cm(2) all-PSCs. The DIO solvent additive is also applicable to other efficient all-PSCs, which proves the advance of generic solvent additive concept for constructing high-performance large-area all-PSCs, and may push forward the commercialization process of all-PSCs.