Novel photodetectors have been developed by using the organic/inorganic hybrid heterostructure of the rubrene/topological insulator Bi₂Se₃, which demonstrate superior photodetection performance benefiting from the Dirac surface state at the heterointerface.

Due to the wide spectral absorption and ultrafast electron dynamical response under optical excitation, topological insulator (TI) was proposed to have appealing application in next-generation photonic and optoelectronic devices. Whereas, the bandgap-free speciality of Dirac surface states usually leads to a quick relaxation of photoexcited carriers, making the transient excitons difficult to manipulate in isolated TIs. Growth of TI Bi ₂ Te ₃ /Ge heterostructures can promote the specific lifetime and quantity of long-lived excitons, offering the possibility of designing original near-infrared optoelectronic devices, however, the construction of TI Bi ₂ Te ₃ /Ge heterostructures has yet to be investigated. Herein, the high-quality Bi ₂ Te ₃ /Ge heterojunction with clear interface was prepared by physical vapor deposition strategy. A significant photoluminescence quenching behaviour was observed by experiments, which was attributed to the spontaneous excitation transfer of electrons at heterointerface via theoretical analysis. Then, a self-powered heterostructure photodetector was fabricated, which demonstrated a maximal detectivity of 1.3 × 10 ¹¹ Jones, an optical responsivity of 0.97 A W ⁻¹ , and ultrafast photoresponse speed (12.1 μ s) under 1064 nm light illumination. This study offers a fundamental understanding of the spontaneous interfacial exciton transfer of TI-based heterostructures, and the as-fabricated photodetectors with excellent performance provided an important step to meet the increasing demand for novel optoelectronic applications in the future.