Exploiting the donor-acceptor-additive interaction's morphological effect on the performance of organic solar cells

Organic solar cells (OSCs) have demonstrated over 19% power conversion efficiency (PCE) with the help of material innovation and device optimization. Co-working with newly designed materials, traditional solvent additives, 1-chloronaphthalene (CN), and 1,8-diodooctane (DIO) are still powerful in morphology modulation towards satisfying efficiencies. Here, we chose recently reported high-performance polymer donors (PM6 & D18-Fu) and small molecular acceptors (Y6 & L8-BO) as active layer materials and processed them by different conditions (CN or DIO or none). Based on corresponding 12 groups of device results, and their film morphology characterizations (both ex-situ and in-situ ones), the property-performance relationships are revealed case by case. It is thereby supposed to be taken as a successful attempt to demonstrate the importance and complexity of donor-acceptor-additive interaction, since the device performance and physics analyses are also tightly combined with morphology variation. Furthermore, ternary blend construction for PCE improvement provides an approaching 19% level and showcases the potential of understanding-guided-optimization (UGO) in the future of OSCs. Two efficient donors and two acceptors are cross-matched with/without CN/DIO treatments to study the donor-acceptor-additive interactions. Twelve sets of devices are fabricated, and the active layers are characterized by in-situ and ex-situ morphological techniques and device physics studying. Furthermore, the ternary blend provides an approaching 19% PCE under the in-depth understanding of morphology.image