Recent Advance in the Development of Singlet-Fission-Capable Polymeric Materials.

Singlet fission (SF) is a spin-allowed process in which a higher-energy singlet exciton is converted into two lower-energy triplet excitons via a triplet pair intermediate state. Implementing SF in photovoltaic devices holds the potential to exceed the Shockley-Queisser limit of conventional single junction solar cells. Although great progress has been made in exploiting the underlying mechanism of SF over the past decades, the scope of materials capable of SF, particularly polymeric materials, remains poor. SF-capable polymer is one of the most potential candidates in the implementation of SF into devices due to their distinct superiorities in flexibility, solution processability, and the ability to achieve nanometer-scale phase separation in thin films through self-assembly. Notably, recent advancements have demonstrated high-performance SF in isolated donor-acceptor (D-A) copolymer chains, leading to efficient dissociation of triplet pair states in thin films, yielding long-lived free triplets. This review provides an overview of recent progress in the development of SF-capable polymeric materials, with a significant focus on elucidating the mechanisms of SF in polymers and optimizing the design strategies for SF-capable polymers. Additionally, the paper discusses the challenges encountered in this field and presents future perspectives. We expect that this comprehensive review will offer valuable insights into the design of novel SF-capable polymeric materials, further advancing the potential for SF implementation in photovoltaic devices. This article is protected by copyright. All rights reserved.