Efficient Wavelength-Selective Self-Powered Organic Photodetectors Based on Electron Acceptors Diluted by Transparent Polymer Donors

Organic photodetectors (OPDs) have great potential in optical communication and biomedical imaging. Wavelength-selective response can be achieved by employing filter-free OPDs with various organic semiconductors. Herein, solution-processed OPDs are fabricated with typical electron acceptors (i.e., PC60BM, ITCC, IT4F, BTP-S2, Y6, and IEICO4F) diluted by transparent polymer donor PTAA. The optical profiles of acceptors drive tunable wavelength detection covering ultraviolet (UV), visible (VIS), to near-infrared (NIR) regions. Compared to a silicon photodetector with nearly uniform photoresponse across wavelengths, fine-tuning the composition of OPDs enables wavelength-selective detection in the UV, VIS, and NIR bands, with higher response than that in out-of-band wavelengths. All the detectors realize specific detectivity over 1011 Jones (based on noise current), fast photoresponse time (<10 μs), and linear photocurrent response around 110 dB at zero bias. Additionally, transient absorption spectroscopy confirms efficient charge generation in PTAA:acceptor blends, which is significantly enhanced by the addition of 1,8-diiodooctane. Besides, the mixed molecular orientations induce spontaneous energetic offsets in the neat acceptor phase, further facilitating charge generation. Therefore, our work demonstrates a universal strategy to realize efficient wavelength-selective self-powered OPDs without optical filters.