Organic solar cells (OSCs) are viable power sources for photovoltaic applications. In this work, a non-fullerene acceptor, PDI-EH, was designed to form a nearly orthogonal structure to suppress its aggregation, and integrated into ternary OSCs. In addition to enhanced photon absorption and matched charge cascade, a PDI-EH acceptor modulated the morphology, which is crucial to affect device efficiency. Detailed analysis revealed that PDI-EH can fine-tune the miscibility of the host donor and acceptor (D/A) materials to form an optimally intermixed phase with short-range molecular order. Photo-induced force microscopy (PiFM) for selective PiFM imaging of D/A materials provided strong evidence that D/A materials formed well-mixed films after PDI-EH incorporation. Additionally, nanoscale spatial mapping of charge carrier dynamics was realized for the first time in a ternary film using a novel transient photo-response atomic force microscopy (TP-AFM) technique. The resulting TP-AFM data revealed a reduced charge transport time, increased charge recombination lifetime and extended charge diffusion length. These improvements brought about by PDI-EH benefit the photovoltaic performance of ternary OSCs under both 1-sun and indoor illuminations. Our work offers insights into morphology modulation and the resulting local charge carrier dynamic, thereby facilitating the development of OSCs in practical applications.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)