Efficient Exciton Dissociation in Heterojunction Interfaces Realizing Enhanced Photoresponsive Performance.

Excitonic effects, originating from the interactions between charge carriers, influence and even dominate the photoresponsive properties of low-dimensional materials. For efficient carrier-related photoresponse, it is imperative to develop appropriate strategies to promote exciton dissociation in these systems. Herein, by taking black phosphorus nanosheets/poly(3-hexylthiophene) (BP/P3HT) as a prototype, we propose that the construction of a heterojunction with a certain band alignment and transport property can facilitate exciton dissociation into free carriers. Analyses on band structures and carrier kinetics confirmed the directional injection of holes from BP to P3HT and the excellent transport property associated with the injected holes in P3HT. Benefiting from these features, the BP/P3HT heterojunction yielded a high photocurrent on-off ratio of ∼18.3, contrasting with the much lower values in pristine BP nanosheets and P3HT. This work provides a feasible scenario for exciton regulation via constructing a heterojunction and establishes an in-depth understanding of exciton dissociation in photoresponsive properties.