π–π Interactions Mediated Pyrene Based Ligand Enhanced Photoresponse in Hybrid Graphene/PbS Quantum Dots Photodetectors

Abstract

Hybrid graphene and quantum dots (QDs) photodetectors merge the excellent conductivity and ambipolar electric field sensitivity of graphene, with the unique properties of QDs. The photoresponsivity of these devices depends strongly on the charge transfer at the graphene/QDs interface. Here 1‐pyrene butyric acid (PBA)‐coated PbS QDs with single layer graphene (SLG) are used to investigate the effect of pyrene as a π–π mediator to enhance charge transfer at the SLG/QDs junction under illumination. The surface chemistry at the QD–QD and SLG/QD interface is studied with the conventional tetrabutylammonium iodide (TBAI) QD linker. The hybrid SLG/QD photodetectors with PBA as a SLG‐QD linker demonstrate a photoresponse up to 30% higher than that recorded for devices where only TBAI is used, due to the strong electron coupling between SLG and QDs. Transconductance measurements show that PBA provokes electron depletion in SLG ascribed to the tendency to delocalize the QDs holes, favoring their transfer to SLG. This surface ligand is found to improve the interaction between the QDs light absorbers and the SLG charge collector, leading to an increased photodetection response. This demonstrates that ligand engineering can enhance charge dynamics and boost the performance of the hybrid device.

Advances in Heterostructures for Optoelectronic Devices: Materials, Properties, Conduction Mechanisms, Device Applications

“…[82] In case of PbS QDs, short organic ligands such as ethanedithiol (EDT) or tetrabutylammonium iodide (TBAI) can be used for the ligand exchange of the PbS QDs (Figure 3a,b). [3,25,60,69,83] Additionally, it is known that the energy level of PbS QDs can be controlled by the ligand species (Figure 3c,d). [84] As mentioned, the insulating feature of QDs is attributed to organic ligands with long hydrocarbon chains, so attempts have been made to exchange these organic ligands with metal chalcogenide complexes (MCCs) starting in 2003.…”

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

“…[ 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. However, large‐scale array imaging is still a considerable challenge due to the engineering bottlenecks and theoretical limitations.…”

Effect of Ligands on the Photoconductivity of HgTe Nanoplatelets

“…These ligands are widely used in solar cells based on PbS/PbSe [7] nanocrystals, therefore a lot of experience in their application has been accumulated. Their short length provides charge carrier transport within nanocrystals layer [8], and they are also one of the main ligands for photodetectors based on nanocrystals for the IR range [9]. EDT is known for providing the best conductivity and is the de facto standard ligand for nanocrystals, while TBAI, being an atomic ligand, provides the smallest distance between nanocrystals and forms a protective layer of iodide on the surface.…”