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

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 via 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.