Solvent‐Resisting Polymer Enabling Self‐Filtering Organic Photodetector With a Fast Response Speed for Wireless Communication

ABSTRACT Photodetectors combining high sensitivity and fast response facilitate real‐time interconnection, which is essential for optical wireless communication systems as a key candidate for future 6G and Internet of Things (IoT) ecosystems. To suppress interference, the community aims for selective detection at 780–1000 nm, where organic photodetectors (OPDs) can particularly deliver efficient photoresponse and spectral selectivity without external optical filters, making it easy to miniaturize and integrate into compact implementations as communication nodes. However, achieving high‐speed operation in self‐filtering OPDs remains challenging, limiting the application in optical communication. Here, we unlocked the potential to combine fast response speed with spectral selectivity via exciton dissociation narrowing (EDN) approach. Based on a thin architecture employing a 280–400 nm thick EDN layer of solvent‐resistant polymer Si25 and a T20:Y14 bulk heterojunction, a fast photocurrent response of µs‐level was obtained, supporting data transmission at 600 kbit/s. Meanwhile, high detectivities of 1 × 10 12 to 1 × 10 13 Jones were obtained across the key communication wavelengths from 780 to 940 nm. The comprehensive characterizations of photoluminescence and transient absorption spectra were also conducted, verifying the importance of strong solvent resistance to achieve the EDN effect.