Organic Photodetectors Achieving UV–Visible Broadband Detection via P3HT-OFET Epitaxial Integration

Organic photodetectors based on organic field-effect transistors (OFETs) are important for the realization of low-cost, large-scale fabrication and high-performance fully flexible devices, owing to their gate-controlled noise suppression mechanism, intrinsic gain amplification effect, and the advantages of solution processability. As a commercially mature organic semiconductor material, poly(3-hexylthiophene) (P3HT) exhibits great potential for developing photodetectors due to its excellent photoelectric conversion efficiency and high carrier mobility. However, because of its large bandgap (∼2.0–2.2 eV), the light absorption wavelength range of P3HT is mainly concentrated in the visible range (∼400–650 nm), which limits its application prospects in broadband photodetectors. To address this problem, a gate epitaxy process is proposed in this paper, wherein a P3HT organic field-effect transistor is efficiently integrated with a photoconductor to achieve the extension of the detection wavelength from visible light to ultraviolet light. In addition, the dual-gate dielectric structure of poly(vinyl alcohol) (PVA) and poly(p-xylylene) (parylene) is adopted in this paper, which not only prevents the problem of solvent corrosion but also overcomes the issues of high hysteresis, low switching speed, and high leakage current associated with single-layer dielectrics, significantly improving the photoelectric response speed of the device. This study provides an effective and widely applicable strategy for applying photodetectors across a broader range of wavelength bands and demonstrates considerable potential for commercializing flexible electronic devices.