Abstract
Although the power conversion efficiency (PCE) of organic photovoltaic (OPV) devices has recently improved to more than 16%, halogenated solution processes are typically employed to obtain optimal performance. However, halogenated processing is harmful to health and the environment, which can be a significant obstacle to commercialization. Therefore, development of active materials processable under halogen-free conditions is of great importance in this field. In this study, a 16.04% OPV device, processed under halogen-free conditions, is developed by employing a new active-blend system, PBDTTPD-HT:BTP-2F-BO. It is highly soluble in halogen-free solvents, forming a preferential bulk-heterojunction morphology. The PBDTTPD-HT:BTP-2F-BO device achieves a PCE comparable with current state-of-the-art devices based on PBDB-TF:BTP-4F (also known as PM6:Y6) using a conventional halogenated process (16.40% versus 16.33%). Furthermore, it demonstrates a significantly higher PCE than the PBDB-TF:BTP-4F device with a halogen-free process (16.04% versus 9.70%).
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•A halogen-free processable OPV device with a PCE of 16.04% is demonstrated•The device achieves a comparable PCE under halogenated and halogen-free processing conditions•The reported device with an active area of ∼1 cm2 achieves a PCE of 14.93%•Preferential energy levels, solubility, and miscibility enhance performance of device
In many cases, processing of organic photovoltaics uses conventional halogenated solvents, such as chloroform and chlorobenzene, which are significantly harmful to health and the environment. Wibowo et al. report a photoactive system that is processable under halogen-free conditions, showing that the active-blend system achieves similar performance under halogenated and halogen-free processing (16.40% versus 16.04%).