Ultrafast-Response and High-Detectivity Self-Powered Perovskite Photodetector Based on Triazine-derived Star-shaped Small Molecule as Dopant-free Hole Transporting Layer

Organic-inorganic hybrid perovskites (OIHP) become appealing for photodetectors due to their excellent optoelectronic properties, but the drawbacks of commonly used interfacial layers in OIHP photodetectors such as necessity of doping, high cost and stability issue hinder the further development of this technology. Herein, a star-shaped small molecule with Triazine core unit named Triazine-Th-OMeTAD is synthesized and employed as a dopant-free hole transporting layer (HTL) in the OIHP photodetectors. Triazine-Th-OMeTAD provides a low-trap-density perovskite film, efficient charge extraction and large electron injection barrier. As a result, the optimized OIHP photodetectors with Triazine-Th-OMeTAD HTL exhibit a low dark current of 1.09 nA/cm2, high responsivity of 0.47 A/W, high specific detectivity of over 8.2×1012 Jones at zero bias. Remarkably, the response speed of 18 ns is obtained at a large active area of 11 mm2. The high-performance OIHP photodetectors demonstrated here offer a promising candidate for low-cost and high-performance near-ultraviolet-visible photodetection, which is applicable in quick frame rate visible imagers, optical communication and many more.