Solid Additive Enables Organic Solar Cells with Efficiency up to 18.6%

Additive strategies play a critical role in improvingthe performanceof organic solar cells (OSCs). There are only a few reports on theapplication of solid additives for OSCs, which leaves a large spacefor further improvement of solid additives and further study on therelationship between material structure and property. PM6:BTP-eC9-basedorganic solar cells (OSCs) were prepared by using a small moleculeBTA3 as a solid additive, and a high energy conversion efficiencyof 18.65% is achieved. BTA3 has good compatibility with the acceptorcomponent (BTP-eC9) and optimizes the morphology of the thin films.Moreover, the introduction of a small amount of BTA3 (5 wt %) effectivelypromotes exciton dissociation and charge transfer and suppresses chargerecombination, and the relationship between the BTA3 content and thedevice parameter is deeply revealed. The use of BTA3 in the activelayers is an attractive and effective strategy for high-performanceOSCs.