Heteroatoms as Rotational Blocking Groups for Non-Fullerene Acceptors in Indoor Organic Solar Cells

Organic solar cells are particularly attractive forindoor and low-light applications; however, photocurrents are lowunder these conditions, and devices are particularly sensitive to thepresence of defects and trap states. A rotational blocking group isoften added to non-fullerene acceptors to reduce both energeticdisorder and the number of defects in the active layer. Theseblocking groups are most often alkyl chains, which require severalsynthetic steps to install; this inevitably lowers yields and increasescosts. Here we report the addition of heteroatom-based blockinggroups to the commonly used non-fullerene acceptor IDIC. Theseblocking groups are synthetically easy to install and highlyeffective; bromination leads to significant improvements in theefficiency of PTQ10:IDIC devices under both one-sun and low-light illumination. In contrast, thioether blocking groups improveefficiency under one-sun illumination but reduce it in dim light, highlighting the need to design and test donor:acceptorsystems specifically for indoor applications

Automated summary

Organic solar cells are attractive for indoor and low-light applications, but face challenges such as low photocurrents and susceptibility to defects. This study introduces heteroatom-based blocking groups to enhance the efficiency of non-fullerene acceptor-based solar cells. The results highlight the importance of designing donor:acceptor systems specifically for indoor applications.