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

As an emerging two-dimensional semiconductor, Bi 2 O 2 Se 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 Bi 2 O 2 Se 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 Bi 2 O 2 Se not only enhanced the device responsivity compared to bare Bi 2 O 2 Se 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 >10 3 A/W at 2 μm. The excellent performance up to 2 μm highlights the potential of field-effect modulated Bi 2 O 2 Se-based hybrid photodetectors in pursuing highly sensitive and broadband photodetection.