Impact of Electrostatic Interaction on Bulk Morphology in Efficient Donor–Acceptor Photovoltaic Blends. (7th June 2021)

• Record Type: Journal Article
• Authors: Ma, Lijiao; Yao, Huifeng; Wang, Jingwen; Xu, Ye; Gao, Mengyuan; Zu, Yunfei; Cui, Yong; Zhang, Shaoqing; Ye, Long; Hou, Jianhui
• Is Part Of: Angewandte Chemie. Volume 133:Number 29(2021)
• Page Start: 16124
• Page End: 16130
• Publication Date: 2021-06-07
• Subjects: bulk morphology -- domain purity -- electrostatic interaction -- non-radiative energy loss -- organic photovoltaic cells; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202102622
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: 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 : By fine‐tuning the molecular electrostatic potential (ESP) distribution of photoactive materials, the morphology of donor:acceptor (D:A) photovoltaic films can be effectively adjusted. A large D:A ESP difference is required to assist charge generation, but too large ESP difference may result in additional nonradiative recombination loss and lead to hypermiscibility issues.