Enhancing Carrier Diffusion Length and Quantum Efficiency through Photoinduced Charge Transfer in Layered Graphene–Semiconducting Quantum Dot Devices

Abstract

Hybrid devices consisting of graphene or transition metal dichalcogenides (TMDs) and semiconductor quantum dots (QDs) were widely studied for potential photodetector and photovoltaic applications, while for photodetector applications, high internal quantum efficiency (IQE) is required for photovoltaic applications and enhanced carrier diffusion length is also desirable. Here, we reported the electrical measurements on hybrid field-effect optoelectronic devices consisting of compact QD monolayer at controlled separations from single-layer graphene, and the structure is characterized by high IQE and large enhancement of minority carrier diffusion length. While the IQE ranges from 10.2% to 18.2% depending on QD-graphene separation, d s, the carrier diffusion length, L D, estimated from scanning photocurrent microscopy (SPCM) measurements, could be enhanced by a factor of 5–8 as compared to that of pristine graphene. IQE and L D could be tuned by varying back gate voltage and controlling the extent of charge separation from the proximal QD layer due to photoexcitation. The obtained IQE values were remarkably high, considering that only a single QD layer was used, and the parameters could be further enhanced in such devices significantly by stacking multiple layers of QDs. Our results could have significant implications for utilizing these hybrid devices as photodetectors and active photovoltaic materials with high efficiency.

Optical Enhancement of Indirect Bandgap 2D Transition Metal Dichalcogenides for Multi‐Functional Optoelectronic Sensors

“…In this current context, 0D semiconducting nanostructures are fascinating objects for the scientific community in nanoscale systems. [35,[112][113][114][115] Quantum confinement makes them attractive in distinct optical properties and intriguing applications that are surprisingly different from bulk semiconductors. Researchers have explored hybrid Quantum Dot (QD)-TMD interaction with various architectural designs, orientation with different experi-mental techniques, and measurement conditions.…”

Engineering sensitivity and spectral range of photodetection in van der Waals materials and hybrids

“…While in graphene it lies between 6%-16% [4]. However, on integration with Q-dots, its IQE can be increased upto 18% [42] and by using quantum well hybrids, it increased to 25% [43]. MoS 2 in an electrolyte bath, with vertical charge transport, shows an IQE as high as 44% [44].…”

High Performance Graphene–C60–Bismuth Telluride–C60–Graphene Nanometer Thin Film Phototransistor with Adjustable Positive and Negative Responses

“…[7][8][9] Since Xia et al prepared the first graphene phototransistor in 2009, [10] graphene has been used in hybrid systems with various materials or even physical local fields to achieve photoelectric detection. [11] For example, metasurfaces, [12][13][14] quantum dots (QDs), [15] nanowires, [16,17] bulk materials, [18] transition metal dichalcogenide materials, [19,20] perovskite materials, [21][22][23] and various organic substances [24][25][26] have been combined with graphene to achieve a high performance photoelectric detection. [27] These works have extensively promoted the research progress of graphene in the field of photoelectric detection.…”