Nonfused Electron Acceptors Based on the 2D-Extended Quinoxaline Core for Organic Solar Cells

Nonfused electron acceptors have recently attracted considerable attention, primarily owing to their inherent merits, which encompass straightforward synthetic methodologies, heightened yield efficiencies, and economic viability. In this study, we have undertaken the deliberate design and synthesis of two distinct nonfused electron acceptors, denoted as BTIC-4F and PTIC-4F, featuring a two-dimensional (2D) extended electron-deficient quinoxaline moiety as the central core and a 4H-cyclopenta[1,2-b:5,4-b′]dithiophene (CPDT) bridge that connects the cores to the terminal groups. The crystallinity and packing behaviors of acceptors have been finely tuned through the strategic manipulation of diverse two-dimensional extended central nuclei. Subsequently, PTIC-4F with a phenanthrene-fused quinoxaline core exhibits enhanced crystallinity and a more organized molecular packing structure. Therefore, this structural optimization translates into a remarkable outcome, with the PBDB-T:PTIC-4F-based device achieving a substantially elevated power conversion efficiency of 11.24% compared to that of its PBDB-T:BTIC-4F counterpart. The findings of our study underscore the promise inherent in extending electron-deficient core units as a viable and fruitful avenue for the design of nonfused electron acceptors.