Ultrahigh Stability 3D TI Bi 2 Se 3 /MoO 3 Thin Film Heterojunction Infrared Photodetector at Optical Communication Waveband

Infrared (IR) detection at 1300–1650 nm (optical communication waveband) is of great significance due to its wide range of applications in commerce and military. Three dimensional (3D) topological insulator (TI) Bi 2 Se 3 is considered a promising candidate toward high‐performance IR applications. Nevertheless, the IR devices based on Bi 2 Se 3 thin films are rarely reported. Here, a 3D TI Bi 2 Se 3 /MoO 3 thin film heterojunction photodetector is shown that possesses ultrahigh responsivity ( R i ), external quantum efficiency (EQE), and detectivity ( D *) in the broadband spectrum (405–1550 nm). The highest on–off ratio of the optimized device can reach up to 5.32 × 10 4 . R i , D *, and the EQE can reach 1.6 × 10 4 A W −1 , 5.79 × 10 11 cm 2 Hz 1/2 W −1 , and 4.9 × 10 4 % (@ 405 nm), respectively. Surprisingly, the R i can achieve 2.61 × 10 3 A W −1 at an optical communication wavelength (@ 1310 nm) with a fast response time (63 µs), which is two orders of magnitude faster than that of other TIs‐based devices. In addition, the device demonstrates brilliant long‐term (>100 days) environmental stability under environmental conditions without any protective measures. Excellent device photoelectric properties illustrate that the 3D TI/inorganic heterojunction is an appropriate way for manufacturing high‐performance photodetectors in the optical communication, military, and imaging fields.