Search

Bulk heterojunctions comprising mixed donor (D) and acceptor (A) materials have proven to be the most efficient device structures for organic photovoltaic (OPV) cells. The bulk morphology of such cells plays a key role in charge generation, recombination, and transport, thus determining the device performance. Although numerous studies have discussed the morphology‐performance relationship of these cells, the method of designing OPV materials with the desired morphology remains unclear. Herein, guided by molecular electrostatic potential distributions, we have established a connection between the chemical structure and bulk morphology. We show that the molecular orientation at the D‐A interface and the domain purity in the blend can be effectively modulated by modifying the functional groups. Enhancing the D‐A interaction is beneficial for charge generation. However, the resulting low domain purity and increased charge transfer ratio in its hybridization with the local excitation states lead to severe charge recombination. Fine‐tuning the bulk morphology can give balanced charge generation and recombination, which is crucial for further boosting the efficiency of the OPV cells. [ABSTRACT FROM AUTHOR]

Bulk heterojunctions comprising mixed donor (D) and acceptor (A) materials have proven to be the most efficient device structures for organic photovoltaic (OPV) cells. The bulk morphology of such cells plays a key role in charge generation, recombination, and transport, thus determining the device performance. Although numerous studies have discussed the morphology‐performance relationship of these cells, the method of designing OPV materials with the desired morphology remains unclear. Herein, guided by molecular electrostatic potential distributions, we have established a connection between the chemical structure and bulk morphology. We show that the molecular orientation at the D‐A interface and the domain purity in the blend can be effectively modulated by modifying the functional groups. Enhancing the D‐A interaction is beneficial for charge generation. However, the resulting low domain purity and increased charge transfer ratio in its hybridization with the local excitation states lead to severe charge recombination. Fine‐tuning the bulk morphology can give balanced charge generation and recombination, which is crucial for further boosting the efficiency of the OPV cells. [ABSTRACT FROM AUTHOR]

Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non‐radiative energy loss (Enon-radloss) is the dominant factor that hinders further improvements in state‐of‐the‐art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed Enon-radloss. Herein, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge‐transfer (CT) state ratio in its hybridization with the local exciton state to facilitate charge generation, but simultaneously result in a larger Enon-radloss. These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells. [ABSTRACT FROM AUTHOR]

Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non‐radiative energy loss (Enon-radloss) is the dominant factor that hinders further improvements in state‐of‐the‐art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed Enon-radloss. Herein, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge‐transfer (CT) state ratio in its hybridization with the local exciton state to facilitate charge generation, but simultaneously result in a larger Enon-radloss. These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells. [ABSTRACT FROM AUTHOR]