A propeller-shaped perylene diimide hexamer as a nonfullerene acceptor for organic solar cells

Abstract

A novel propeller-shaped molecule (HPB-PDI₆) with a hexaphenylbenzene (HPB) core and six peripheral PDI units was synthesized via Co₂(CO)₈-catalyzed cyclotrimerization and used as an acceptor for organic solar cells (OSCs). The intriguing geometry of the HPB core and the spatial repulsion of the PDI rings created a twisted three-dimensional propeller-shaped conformation for HPB-PDI₆. The propeller-shaped conformation could prevent the acceptor molecules from forming large aggregates in the active layer. As expected, the PTB7-Th:HPB-PDI₆ blend films show a favorable morphology as well as high and balanced charge carrier mobility. Devices based on PTB7-Th:HPB-PDI₆ achieved a PCE of 6.63% with a V_oc of 0.92 V, a J_sc of 15.11 mA cm⁻², and an FF of 48.0%. Our results have demonstrated that the easily prepared propeller-shaped HPB-PDI₆ could be a promising acceptor for high efficiency organic solar cells.