PbSe Quantum Dots Sensitized High-Mobility Bi₂O₂Se Nanosheets for High-Performance and Broadband Photodetection Beyond 2 μm

Abstract

As an emerging two-dimensional semiconductor, Bi₂O₂Se has recently attracted broad interests in optoelectronic devices for its superior mobility and ambient stability, whereas the diminished photoresponse near its inherent indirect bandgap (0.8 eV or λ = 1550 nm) severely restricted its application in the broad infrared spectra. Here, we report the Bi₂O₂Se nanosheets based hybrid photodetector for short wavelength infrared detection up to 2 μm <i>via</i> PbSe colloidal quantum dots (CQDs) sensitization. The type II interfacial band offset between PbSe and Bi₂O₂Se not only enhanced the device responsivity compared to bare Bi₂O₂Se but also sped up the response time to ∼4 ms, which was ∼300 times faster than PbSe CQDs. It was further demonstrated that the photocurrent in such a zero-dimensional-two-dimensional hybrid photodetector could be efficiently tailored from a photoconductive to photogate dominated response under external field effects, thereby rendering a sensitive infrared response >10³ A/W at 2 μm. The excellent performance up to 2 μm highlights the potential of field-effect modulated Bi₂O₂Se-based hybrid photodetectors in pursuing highly sensitive and broadband photodetection.