Self-Driven and Blue-Enhanced Photodetectors Based on Organic/Inorganic Heterojunction of Pentacene and Bi2Se3

Nanoscale-thick organic/inorganic hybrid heterojunction functioning as the core optical active layer of a photodetector has many significant advantages due to its enhanced light absorption, excellent interface quality, higher mechanical stability, and intralayer excitonic dynamics. However, via controlled growth of high-quality 2D pentacene/Bi2Se3 heterojunction to further improve the performance metrics of photodetectors has rarely been investigated. Therefore, to further explore its utilization potentiality in optoelectronics, the newly conceived organic/inorganic heterojunctions with sharp interface were controllably grown based on small-molecule pentacene and topological insulator Bi2Se3 nanometer films. Then, a self-driven and blue-sensitive heterojunction photodetector was fabricated. Note that the photodetector with nanoscale thickness exhibits a reversible photocurrent switching performance with higher photoresponsivity of 4.834 A/W and detectivity of 1.62 × 1010 Jones under 405 nm blue-light irradiation. Through integrating several surface-sensitive characterization techniques, the robust interface Schottky potential was experimentally revealed, which was derived from the metallic and few nanometers thick Dirac surface state of the Bi2Se3 crystal. This contact behavior is beneficial to improve the separation capability of electron–hole pairs and promotes the photoelectric conversion efficiency of the heterojunction. This study provides an in-depth understanding of the basic photophysics of pentacene/Bi2Se3 heterojunctions, and the newly designed photodetector has broad application prospects in low-power and flexible optoelectronics.