Adjusting the Active Layer Morphology via an Amorphous Acceptor Solid Additive for Efficient and Stable Nonfullerene Organic Solar Cells

It is incredibly feasible and effective to adopt a solid additive strategy to optimize the active layer blend films morphology for nonfullerene organic solar cells (OSCs) to achieve high efficiency and stable performance. Herein, a novel amorphous small molecule SJ‐IC‐M with a comparatively high molecular weight is first designed and used as an efficient solid additive in the OSCs based on PM6:Y6 to enhance the power conversion efficiency (PCE) and long‐term stability of the device. After the addition of 0.5 wt% SJ‐IC‐M into the active layer blends, the PCE can be increased to 16.2% compared with that of the reference device without additive displaying an inferior PCE of 15.0%. Moreover, the device containing the SJ‐IC‐M additive delivers more excellent long‐term stability. The PCE can remain over 90% of its initial value when the unencapsulated device is preserved in a N 2 ‐filled glovebox for a month. Systematic analysis reveals that the introduction of the relatively high molecular weight amorphous SJ‐IC‐M additive can optimize the crystallinity of Y6. As a result, an improved charge transport, stabilized blend morphology, and enhanced device performance are achieved. Moreover, the current research provides a new strategy which can replace the commonly used solvent additive to fabricate efficient and stable nonfullerene OSCs.