High Speed Dual‐Mode Photodetector of Large‐Area π‐Conjugated Conductive MOFs Film on Si‐Based Substrate

ABSTRACT Two‐dimensional π‐conjugated Ni 3 (HITP) 2 MOFs have attracted widespread attention due to their ordered metal‐ligand coordination and π‐conjugated structure, while its potential in photodetectors is not fully explored. In this work, large‐area Ni 3 (HITP) 2 thin film is integrated with high‐resistivity n‐type silicon to construct a self‐powered photodetector featuring high‐speed and dual‐mode response. Benefiting from a highly delocalized π‐conjugated system enabling efficient charge transport both intra‐layer and inter‐layer, Ni 3 (HITP) 2 acts as an electrode transport layer similar to graphene. By regulating the built‐in electric field with the applied bias, the device operates in photovoltaic mode under zero or negative bias, and switches to photoconductive mode under positive bias. Notably, the device exhibits an ultra‐fast response time of 640 ns under the power density of 2.86 mW/cm 2 at zero bias, along with a high specific detectivity of 2.42 × 10 13 Jones. Its broadband absorption extends the operational wavelength of silicon‐based device to 1550 nm. Additionally, it can produce high‐resolution images in both modes. This study highlights the comprehensive advantages of Ni 3 (HITP) 2 , demonstrating its great potential for silicon‐based optoelectronic integration and intelligent applications.