Here, we propose a planar hot-electron photodetector based on broadband Tamm plasmon resonance using a TiN layer, n-type doped Si layer, and seven pairs of DBRs. Simulation results show high absorption (94.2%) with a full width at half maximum of 239.3 nm, which is 2.9 times that of the Au/DBR configuration. We predict that the photoresponsivity can reach 26.1 mA W-1 at 1140 nm. Since the planar nanofilms for TP resonance are facile to fabricate, this work promotes hot-electron applications in broadband photodetection and other broadband light-harvesting applications.