Such 2D/2D vdWHs show unique properties, such as high carrier mobility, atomic-scale depletion region and tunable light-matter interactions, which stem from the designed energy band alignment and the ultrafast interfacial charge transfer. However, the interlayer coulomb interactions and the carrier scatterings are dominant in such atomically-thin layers, which have great influence on the performance of optical behaviors and optoelectronic devices. These kinds of devices still suffer from performance limitations due to their weak light absorption and natural atom defects.
The authors of this paper designed a 0D/2D mix-dimensional vdWHs (ZnS/CdSe QD/MoS
2) to investigate the light-controlled charge transfer processes at the interface and fabricate high-performance photodetectors working in both weak and strong light environment. The steady-state and transient-state optical measurements of colloidal QDs, MoS
2 monolayers and heterostructures are systematically investigated, showing tunable PL spectra and ultrafast charge transfer stemmed from a type-II band alignment.
These power-sensitive charge transfer processes at the interface help to improve the performance of optoelectronic devices based on TMDs with large responsivity and detectivity at both low and high light powers. The difference of device performance of MoS
2 and 0D/2D heterostructure has been systematically compared, and the deep discussion of device performance on the effect of interfacial charge doping has been provided. The hybrid phototransistor exhibits typical N-type behaviors in the dark environment. The photocurrent intensity (I
ph) of heterostructure device is 2.3 times larger than that of MoS
2 device, which is arising from the strong absorption characteristics of quantum dots and effective charge separation. The photoresponsivity (R) of the heterostructure device reaches up to 4.35 times larger than that of MoS
2 device (856 AW
-1 vs 3.72×10
3 AW
-1), which exhibits outstanding performances compared with other TMD-based photodetectors. The highest detectivity of (D*) heterostructure device gets improved up to 28 times (6.95×10
10 Jones
vs 1.95×10
12 Jones). The heterostructure photodetector exhibits stable and reproducible on-off photoelectric switching characteristics with an average rise time of 0.49 s and a fall time of 0.6 s, respectively.
These results are expected to soon provide the fundamental understanding of light-controlled charge transfer in 0D/2D mix-dimensional vdWHs, which contributes to the design of high-performance smart optoelectronic devices.
COMPAMED-tradefair.com; Source: Opto-Electronic Advances
