High-Performance Organic Photodetector with Porous Quasi-Planar Heterojunction via Breath-Figure Strategy

The detectivity ( D *) of organic photodetectors (OPDs) can be enhanced through increasing photocurrent ( J light ) and reducing dark current ( J dark ). While simply increasing the active layer thickness effectively lowers dark current, this approach simultaneously promotes charge recombination, demonstrating the inherent thickness-dependent trade-off between J light and J dark . To address it, precise control of donor–acceptor phase separation emerges as an effective strategy to facilitate charge transfer while suppressing excessive recombination. In this work, we utilize PM6 as the donor and Y6 as the acceptor, employing a combined breath-figure (BF) and layer-by-layer (LbL) approach to fabricate an ordered wrinkled active layer. This unique porous structure enables uniform acceptor diffusion throughout the donor phase, creating abundant donor–acceptor interfaces and ultimately forming a 300 nm thick active layer with pseudoplanar heterojunction. The resulting OPD device exhibits high performance of remarkably low dark current (8.88 × 10 –10 A cm –2 ) and a peak D * of 2.23 × 10 13 jones, significantly outperforming conventional bulk heterojunction OPD devices ( J dark, 2.00 × 10 –8 A cm –2; D *, 5.05 × 10 12 jones). Notably, our devices maintain D * values exceeding 10 13 jones across a broad spectral range (480–870 nm), covering the entire visible-light spectrum. Overall, this work presents an effective strategy for overcoming detectivity limitations in OPDs and establishes a promising pathway for their application in flexible visible-light photodetectors.