Green-Solvent-Processed All-Polymer Solar Cells Containing a Perylene Diimide-Based Acceptor with an Efficiency over 6.5%

To realize high power conversion efficiencies (PCEs) in green-solvent-processed all-polymer solar cells (All-PSCs), a long alkyl chain modified perylene diimide (PDI)-based polymer acceptor PPDIODT with superior solubility in nonhalogenated solvents is synthesized. A properly matched PBDT-TS1 is selected as the polymer donor due to the red-shifted light absorption and low-lying energy level in order to achieve the complementary absorption spectrum and matched energy level between polymer donor and polymer acceptor. By utilizing anisole as the processing solvent, an optimal efficiency of 5.43% is realized in PBDT-TS1/PPDIODT-based All-PSC with conventional configuration, which is comparable with that of All-PSCs processed by the widely used binary solvent. Due to the utilization of an inverted device configuration, the PCE is further increased to over 6.5% efficiency. Notably, the best-performing PCE of 6.58% is the highest value for All-PSCs employing PDI-based polymer acceptors and green-solvent-processed All-PSCs. The excellent photovoltaic performance is mainly attributed to a favorable vertical phase distribution, a higher exciton dissociation efficiency (P-diss) in the blend film, and a higher electrode carrier collection efficiency. Overall, the combination of rational molecular designing, material selection, and device engineering will motivate the efficiency breakthrough in green-solvent-processed All-PSCs.