A general strategy to ultrasensitive Ga2O3 based self-powered solar-blind photodetectors

Ga 2 O 3 based self-powered photodetectors , which can work in photovoltaic mode, show great potential applications in the next-generation photodetectors. Due to the difficulty of p-type doping of Ga 2 O 3 , constructing heterojunctions is a promising alternative for self-powered Ga 2 O 3 photodetectors. Although several inorganic materials have been focused on fabricating Ga 2 O 3 based heterojunction, some disadvantages prevent them from being widely used, such as the large lattice mismatch , the unsuitable bandgap, the inflexibility, the complex preparation process, etc. In this study, a general strategy has been proposed for high-performance photodetectors through building a type-Ⅱ Ga 2 O 3 heterojunction with the small-molecule hole transport materials (SMHTMs). The relatively large hole mobility of SMHTMs guarantees the high-speed transport of the photogenerated holes, and the solar-blind filter effect of the SMHTMs films makes the photodetector highly spectrum selective. Herein, four types of SMHTMs have been used to constructed photodetectors with Ga 2 O 3 , and all of them exhibit self-powered characteristics with I on / I off ratios of about>10 5 , which is 1–2 orders of magnitude larger than these previously reported Ga 2 O 3 photodetectors. Among them, the photodetector based on β -Ga 2 O 3 /TAPC heterojunction shows the best photoelectrical performances with a dark current of about 20 fA, a I on / I off ratio of 5.9 × 10 5 , and a detectivity of 1.02 × 10 13 Jones at 0 V, all of which are amongst the best values ever reported for Ga 2 O 3 based self-powered photodetectors. The high-speed transport of the photogenerated holes and large built-in field in the β -Ga 2 O 3 /SMHTMs heterojunctions should be responsible for these remarkable performances. This work provides a feasible strategy to high-performance Ga 2 O 3 based self-powered photodetectors, thus may push forward their applications.