In this work, we have introduced single/double-sided N-annulated perylene bisimide (PBI) with deep energy levels into double-cable polymers with poly[1-(5-(4,8-bis(4-chloro-5-(2-ethylhexyl)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b']dithiophen-2-yl)thiophen-2-yl)-5,7-bis(2-ethylhexyl)-3-(5-methylthiophen-2-yl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione] (PBDB-T-Cl) as a donor backbone, marking as s-PPNR and as-PPNR, according to the molecular symmetry. Both double-cable polymers displayed a high open-circuit voltage approaching 1.20 V in light of high energy level discrepancy between electron-donating and electron-withdrawing parts, which is the highest open-circuit voltage among double-cable-based single-component organic solar cell (SCOSC) devices. Additionally, the asymmetric polymer displayed improved absorption spectra, thereby promoting crystallization and phase separation. Consequently, the as-PPNR-based SCOSCs achieved a power conversion efficiency of 5.05% along with a higher short-circuit current density and fill factor than their s-PPNR-based counterparts. In this work, we have successfully incorporated N-annulated PBI into double-cable polymers and revealed the important effects on structural symmetry and phase separation of double-cable polymers for higher SCOSC performance.
Keywords: N-annulated perylene bisimides; double-cable polymers; molecular symmetry; phase separation; single-component organic solar cells.