Nanohybrid Photodetectors

Abstract

Little imagination is needed to gauge the impact of lowdimensional nanostructures such as 0D quantum dots (QDs) and nanocrystals (NCs), [1][2][3][4] 1D nanowires (NWs) and nanotubes, [5,6] and 2D atomic sheets (graphene, MoS 2 , etc.). [7][8][9] With the exponential increase in the discovery of low-dimensional nanostructures, and in understanding how different and how peculiar the electrons behave when confined in the 0D, 1D, and 2D limits, an immediate next step is followed to use these low-dimensional nanostructures as "lego" pieces to build a variety of devices for electronic, photonic, and optoelectronic applications with functionality and performance unprecedented by, or better than that of, their counterparts based on conventional 3D materials. In such a quest, nanohybrids with regard to either heterostructures of the low-dimensional nanostructures, or their heterostructures with conventional materials (bulks, films, polymers, etc.), have emerged as an important class of nanomaterials for practical applications in electronic devices, photonic devices, optoelectronic devices, structural devices, medicine, sensors, etc. In fact, the past decade or so has witnessed exciting progress made in the research and development of nanohybrids, promoted particularly by the discovery of a large variety of 2D atomic materials including graphene, transition metal dichalcogenides (TMDCs), etc. [7][8][9] Despite differences in various nanohybrids stemming from different device requirements, all nanohybrids have one thing in common: the presence of heterojunction interfaces that play a critical role in the functionality and performance of the nanohybrids-based devices. This explains an intensive effort in recent research toward understanding and controlling such interfaces. Optoelectronic nanohybrids, such as QDs/graphene nanohybrids, present an excellent example. During the optoelectronic process of light absorption, exciton (or photogenerated electronhole pairs) dissociation into free charge carriers, charge transfer, and transport, the QD/graphene interface affects almost the entire process by providing the required band-edge offset for exciton dissociation and the electric field to drive the charge transfer. As the dimensions or at least one of the dimensions of the low-dimensional nanostructures approach from sub-nm to a few nm, the effect of such heterojunction interfaces on the nanohybrid properties becomes increasingly critical and controlling such interfaces must be at an atomic scale. This represents a major challenge toward achieving the anticipated nanohybrids' device performance, especially in practical applications that require wafer-scale synthesis, manipulation, and characterization of these atomically small, single-crystalline lowdimensional nanostructures. It should be noted that many excellent reviews or book chapters are available in literature covering the recent progress made in fabrication, characterization, and applications of nanohybrids. [8][9][10][11][12][13][14][15][16] Instead, this article intend...

WS2–Polyaniline Nanohybrid Materials for High-External Quantum Efficiency Photoelectric Devices Utilized in Flexible Electronics

“…37,38 This may entail investigating new device topologies, creating effective fabrication techniques, and assessing how well the material works with current technologies. 29 The hybrid organic−inorganic photodetectors highlight the exceptional electrical and optical characteristics of organic compounds along with those of inorganic materials, such as broadband absorption, light−matter solid interaction exacerbated by excitonic resonances, and the intrinsic carrier mobilities. 4,16,39 In addition, the peculiar reactions at organic−inorganic interfaces brought on by interactions including covalent bonding and π−π* transitions are advantageous for photodetection.…”

“…The performance of the WS 2 –PANI nanohybrid material in a photodetector device is examined in the study, along with its characterization and production . The outcomes show that the photodetection performance of the nanohybrid material is greatly improved, making it a promising solution for various photodetection applications. − It can be challenging to achieve flexibility, especially in typically hard materials like metals or ceramics . Flexible plastics, elastomers, and nanomaterials are just a few of the methods and materials engineers and scientists have created to make flexible structures and devices .…”

Probing performance limiting factors in uncooled quantum dots/graphene SWIR-MWIR detectors

“…Among others, the one based on graphene and colloidal quantum dots heterostructures (QD/Gr) are particularly promising for photodetectors, 10 taking advantages of recent research progress in development of colloidal QDs of semiconductors of different bandgaps and hence different optical cutoffs for photodetection in different spectral range [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] and high carrier mobility graphene for high-performance photodetection. 28 Figure 1 compares the QD/Gr heterostructure nanohybrids photodetectors (Figure 1a) with the QD-only (Figure 1b) and graphene-only (Figure 1c) counterparts. The QD/Gr nanohybrids is a quantum device, taking advantage of the strong quantum confinement in QDs with enhanced light-matter interaction, spectral tunability, and suppressed phonon scattering 18,29,30 , and of the extraordinary charge mobility of graphene at room temperature.…”

“…After the first report of PbS QD/graphene photodetectors by Konstantatos et al about a decade ago, 10 many QD/Gr nanohybrids photodetectors have been explored with high photoresponsivity and gain (or EQE). 28,55 The photoresponse of the QD/Gr nanohybrids is a photo-gating effect on graphene measured between the source and drain electrodes upon light illumination. The gain is defined as: gain=τc/τt 10,36,[56][57][58][59] , where τc is the exciton life time in QDs and τt is the carrier transit time defined as: τt=L 2 /µVsd.…”

“…For example, charge traps can form on the QD surface and QD/graphene interface, resulting in low photoresponse and response speed. 68,69 In the infrared spectrum, the effect of QD surface states can be more significant with decreasing bandgaps. This means understanding and based on which engineering the QD surface and QD/graphene interface is critical and imperative to achieving high performance QD/Gr nanohybrids SWIR-MWIR photodetectors.…”