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(a) The energy band diagram of the graphene/CdSe Schottky junction connected with a load under light illumination, together with the corresponding equivalent circuit. F G is the work function of graphene, F B is the Schottky barrier height, V i is the built-in potential, q is the charge of the electron, V is the voltage drop on the load, and c S is the electron affinity of CdSe. E C , E V , and E F are the conduction band edge, valence band edge, and Fermi level of CdSe, respectively. (b) Current–voltage (I–V) characteristic of a typical CdSe NB/graphene Schottky junction in the dark.
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Flexible and transparent electronic and optoelectronic devices have attracted more and more research interest due to their potential applications in developing portable, wearable, low-cost, and implantable devices. We have fabricated and studied high-performance flexible and transparent CdSe nanobelt (NB)/graphene Schottky junction self-powered pho...
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... Unlike the junction of p-n, which has a minority carrier storage effect, Schottky junctions are inherently a majority carrier device [12,13]. Moreover, the fabrication process of the Schottky junction device is generally simple because it does not require charge transport layers, making it compatible with the existing semiconductor manufacturing [14,15]. Recently, halide perovskites have been extensively used in the manufacture of Schottky junction PDs [16]. ...
Self-powered photodetectors (SPPDs) are attracting considerable publicity due to their superiority over conventional photodetectors (PDs) in terms of high sensitivity, fast response, and no need for an external power supply. Halide perovskites are much anticipated in SPPDs for their unusual photoelectronic properties. This work developed a Schottky junction ${{\rm CsPbBr}_3}/{\rm n} \text{-} {\rm Si}$ C s P b B r 3 / n - S i SPPD by growing stable all-inorganic ${{\rm CsPbBr}_3}$ C s P b B r 3 microcrystals on an n-Si substrate using a solution method. At zero bias, such Schottky SPPD has a very weak dark current (0.3 pA), a wide linear dynamic range (LDR, 110 dB), a sizeable on–off ratio ( ${\gt}{{10}^3}$ > 10 3 ), and high detectivity ( ${1.05} \times {{10}^{11}}\;{\rm Jones}$ 1.05 × 10 11 J o n e s ). Through the research of this project, it is expected to obtain a way to prepare Schottky photodiodes with high stability and self-driving capability.
... This value is much larger than that of most vdWHs, [35,36]indicating there is a strong built-in electric field across the Te/CdSe interface, which could facilitate the separation and transfer of the electron-hole pairs. Previous works have demonstrated the bandgap and work function of Te flakes are 0.32 eV and ∼4.71 eV, [37] while the electron affinity and bandgap of multilayer CdSe are ∼3.8 eV and 1.74 eV [38,39]. The optical bandgap of CdSe can be verified from the UV-vis absorption spectrum shown in Fig. 2(d). ...
Self-driven photodetectors, which can detect optical signals without external voltage bias, are highly attractive in the field of low-power wearable electronics and internet of things. However, currently reported self-driven photodetectors based on van der Waals heterojunctions (vdWHs) are generally limited by low responsivity due to poor light absorption and insufficient photogain. Here, we report p-Te/n-CdSe vdWHs utilizing non-layered CdSe nanobelts as efficient light absorption layer and high mobility Te as ultrafast hole transporting layer. Benefiting from strong interlayer coupling, the Te/CdSe vdWHs exhibit stable and excellent self-powered characteristics, including ultrahigh responsivity of 0.94 A W⁻¹, remarkable detectivity of 8.36 × 10¹² Jones at optical power density of 1.18 mW cm⁻² under illumination of 405 nm laser, fast response speed of 24 µs, large light on/off ratio exceeding 10⁵, as well as broadband photoresponse (405-1064 nm), which surpass most of the reported vdWHs photodetectors. In addition, the devices display superior photovoltaic characteristics under 532 nm illumination, such as large Voc of 0.55 V, and ultrahigh Isc of 2.73 µA. These results demonstrate the construction of 2D/non-layered semiconductor vdWHs with strong interlayer coupling is a promising strategy for high-performance and low-power consumption devices.
... Graphene is one of the most versatile 2D materials used for making the Schottky contacts on CdSe and ZnO materials [8], [9], [15]. Jin et al. [8] fabricated a graphene-based Schottky junction on a CdSe nanobelt (NB) at 1000° using the chemical vapor deposition (CVD) method shown in Figure rise-time and 137 fall-time. ...
The simplest form of the photodetectors is a p-n junction device operated under reverse bias condition. Thus, requirement of a power supply source is essential for the operation of photodetectors. Self-powered photodetectors are a class of devices which requires no external power supply for their operation. Such type of photodetectors may play crucial roles in the Internet of Things (IoTs) and optical sensor networks. Therefore, the present chapter is dedicated to present some recent developments in II-VI group semiconductor-based self-powered photodetectors. Different types of photodetector structures with their working principles have been discussed.
... Gao et al. reported for the first time a high-performance flexible transparent CdSe nanoribbon/ graphene as Schottky junction self-powered photodetector. [132] Adv. Funct. ...
... Reproduced with permission. [132] Copyright 2013, Royal Society of Chemistry. d) Structural schematic diagram of the p-GaN/n-ZnO heterojunction-based photodetector and the I-V characteristics of GaN/ZnO heterojunction photodetector. ...
With the development of the Internet of Things (IoT), there is an increasing need for clean energy and large‐scale sensory systems. Triboelectric/piezoelectric nanogenerators (TENGs/PENGs), have attracted considerable attention as a new type of power generation terminal, which can harvest surrounding energy and convert it into electrical energy. To improve the output performance of nanogenerators (NGs) and diversify related applications, 2D materials with high carrier mobility and excellent piezoelectric properties can be directly used or integrated as different types of self‐powered sensors. In this review, the authors first introduce the excellent piezoelectric and optoelectronic properties of 2D materials, followed by the triboelectric series of 2D materials used in TENGs. The categories of integrated self‐powered sensors based on 2D materials are then summarized according to their different structures and compositions. We also discuss in detail the recent applications of integrated self‐powered sensors based on 2D materials from five aspects. Finally, the challenges and outlooks in the research field of self‐powered sensors are featured. Given the continuous development of self‐powered sensors based on 2D materials, they are considered to have significant potential for applications in biomedicine, environmental detection, human motion monitoring, energy harvesting, and smart wearable devices.
... Particularly, cadmium selenide (CdSe) is one of the most extensively studied semiconductors owning to its size-tunable properties for nanostructures [19][20][21]. Z. Gao et al. fabricate photovoltaic detectors employing CdSe NB and graphene Schottky junction, and achieve high photosensitivity and short response and recovery times under illumination at 633 nm [22,23]. L. Dong et al. investigate the piezo-phototronic effect on transport properties of CdSe NW, and obtain a fast response and recovery [24]. ...
We theoretically investigate the propagation and non-reciprocal properties of cadmium selenide (CdSe) nanowire (NW), and achieve strongly field enhancement at communication wavelength of 1550 nm when combined with the hybrid nanostructure. By varying the parameters of the nanostructure, i.e., MgF2 and Ag substrates, together with grooves, relations between these properties and the parameters are illustrated in details. Particularly, with an optimal design, the propagation performance of the NW is highly improved. Moreover, by breaking the symmetry of the system, the non-reciprocal property without time modulations is obtained with high contrast employing the further optimal design. These novel results are significant to related applications such as photonic integrated circuit and optical communications.
... Group II-VI semiconductors (e.g., CdS, CdSe, ZnS, ZnSe, CdTe, and ZnTe) nanostructures have received significant attention in recent years because of their unique optoelectronic properties(99). All of the group II-VI hybrid photodetectors, including graphene/CdS (100), graphene/CdSe(101,102), and graphene/ZnS (103), show high photodetection performance, such as responsivities exceeding hundreds to thousands of amperes per watt, on/off ratios of more than 10 4 , and switching speeds in the sub-microsecond range. Metal oxide semiconductors also have attractive optoelectronic properties, such as excellent electron mobility even in the amorphous state, high optical transparency, and mechanical flexibility(104). ...
At present, halide perovskite (HP) materials, as a family of promising semiconductors, have been a hot topic in the field of energy and optoelectronic technologies. These materials offer a range of remarkable properties like large absorption coefficients, tunable bandgaps, high carrier mobilities, and long carrier diffusion lengths, etc. Besides these physical properties, due to their low-cost and low-temperature solution processability, HPs are becoming materials of research interests among researchers. Among various optoelectronic applications based on perovskites, photodetectors are the remarkable one which has attached considerable research interests. However, efficient photo-generated carrier extraction and faster carrier transport are the fundamental requirements for good photodetection. Unfortunately, during perovskite thin film (PTF) preparation through the solution process, pinhole generation is prevalent. Therefore, photo-generated carrier face unwanted recombination and trapping. These pinholes are the product of atomic vacancies (AV), and AVs are one of the main causes of hysteresis. In this respect, morphology engineering (ME) of solution-processed PTFs to mitigate hysteresis is mandatory. Exploring different anti-solvents treatments is an option. Carbon nanomaterials (CNM) also can help to reduce unwanted recombination and trappings by improving the TFs’ quality. Among various CNMs, the carbon nanotubes (CNT) are very suitable to make promising composite TFs for high-performance devices. CNTs also help in efficient carrier extraction and faster transmission. Again, all-inorganic perovskites (AIP) offer better stability compared to organic-inorganic hybrid perovskites (OIHP) in an ambient environment. Moreover, the popular Pb-based AIPs pose a potential environmental threat. In this thesis, I am interested in exploring the ME and hybridization of AIPs (CsSnI3) with CNTs and related photodetectors.
... 256 A CdSe nanobelt/graphene flexible detector showed a responsivity of 8.7 A W À1 , a sensitivity of 1.2 Â 10 5 and a response time of 70 ms under 633 nm light irradiation with a 3500 Hz switching frequency. 257 The self-powered detection was observed with a graphene/MoSe 2 /Au device due to the asymmetrical contact nature where the Schottky junction between MoSe 2 and graphene enabled the device to work without any bias and the ohmic conduction between Au and MoSe 2 resulted in a fast response. 258 A graphene/single GaAs nanowire Schottky junction photovoltaic device demonstrated a high photoresponsivity of 231 mA W À1 and a fast recovery time of 85/118 ms at zero bias. ...
In recent years, 2D layered materials have emerged as potential candidates in the opto-electronic field due to their intriguing optical, electrical and mechanical properties. Photodetectors based on 2D materials have been reported to exhibit excellent photodetection capability due to their tunable bandgap and ability to detect broadband spectrum ranging from UV to NIR. Schottky junction-based detectors are highly sensitive and fast responsive compared to other heterojunction devices. Schottky contacted devices are fabricated by constructing a heterojunction of a semiconductor with a metal or a metal-like material. In the case of 2D material-based photodetectors, either the semiconductor or the metal belongs to the 2D family. The detection properties of Schottky contacted devices are mainly dependent on the junction properties such as the barrier height. The photodetection performance of detectors with 2D materials is observed to be superior and further it can be enhanced by tuning the properties through various strategies. Herein, the basic concepts, detection mechanism and evaluation parameters of Schottky junction-based photodetectors and the recent developments in Schottky junction-based photodetectors achieved using various 2D materials in the past five years are reviewed. Emerging strategies to enhance the performance by adjusting the Schottky barrier height are elaborated. Finally, the summary and future prospects are provided. This journal is
... [98] Group II-VI semiconductors (e.g., CdS, CdSe, ZnS, ZnSe, CdTe, and ZnTe) nanostructures have received significant attention in recent years because of their unique optoelectronic properties. [99] All of the group II-VI hybrid photodetectors, including graphene/CdS, [100] graphene/CdSe, [101,102] and graphene/ZnS, [103] show high photodetection performance, such as responsivities exceeding hundreds to thousands of amperes per watt, on/off ratios of more than 10 4 , and switching speeds in the sub-microsecond range. Metal oxide semiconductors also have attractive optoelectronic properties, such as excellent electron mobility even in the amorphous state, high optical transparency, and mechanical flexibility. ...
Over the last few years, metal halide perovskites have established themselves as important materials in the field of optoelectronics. After their first application in photovoltaics, they have been successfully used in other optoelectronic devices, especially photodetectors, owing to their unparalleled optical and electronic properties. Notably, because of their unique optical and electronic properties and small physical dimensions, various carbon nanomaterials have emerged as alternatives for next‐generation optoelectronic devices, and they have also been combined with other materials to realize optimal optoelectronic performance. Some implementations of hybrid photodetectors combining metal halide perovskites with carbon nanomaterials have been reported. Here, it is presented a comprehensive review of the recent advancements in the application of carbon nanomaterials in metal halide perovskite photodetectors, with particular focus on the possible working mechanisms behind the significant enhancement of their performance. First, a brief introduction to the fundamentals of photodetection devices is presented, followed by a short discussion of the intrinsic characteristics of metal halide perovskites and carbon nanomaterials. Detailed descriptions of the operation mechanisms, the evolution of different device structures, and their optoelectronic performance are then given. Finally, the potential challenges and future perspectives for the development of high‐performance stable photodetectors based on these materials are outlined.
... It is also expectable that the molar concentration of the various compositional complexes can play a crucial role in the reaction kinetics of CdSe nanostructures which is not reported yet to the best of our knowledge. Photoresponse characteristics of CdSe nanoparticle is also of considerable interest over the years from the application point of view in optoelectronic devices [15][16][17][18][19]. ...
Cadmium selenide (CdSe) nanoparticles dispersed in the PVP matrix with varying concentrations of cadmium (Cd) ion complex have been synthesized through a low-cost chemical bath deposition technique to investigate the effects of cadmium ion concentration on its optical and photo-response characteristics. To confirm the formation of pure, stable, well dispersed, and highly crystalline spherical CdSe nanocomposites different characterization techniques such as X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Fourier transform infrared spectroscopy have been used. The optical band gaps and sizes of the nanocomposites are determined from the UV–Vis data while the surface-related emission properties of the CdSe nanocomposites are obtained from the PL data. The quantum confinement on the CdSe nanocomposites increases with the decrease of Cd ion concentration. I–V characteristics measurements have been done on the samples to investigate the photo-response properties of the samples. Various optical properties such as bandgap, near bandgap emission, and impurity emission are correlated with the photo-response properties of the samples. The photoresponse properties are found to become more suitable for application in white light photosensor with the increase of quantum confinement. Mechanisms related to the enhancement of photocurrent with respect to quantum confinement are also discussed in this paper.
... 36 Flexible photodetectors are expected to be important elements of wearable optoelectronic technology in elds from biomedical imaging to surveillance and high-speed broadband optical communication. Flexible photodetectors have been developed using a variety of nanomaterials, from traditional semiconductors, such as Si, Ge, Se, GaP, InP, CdS and ZnSe, [42][43][44][45][46][47][48][49] to newly emerging perovskites, 75,76 as a very wide variety of hybrid heterostructures involving polymers, metal oxides, CNTs, graphene, transition metal trichalcogenides, etc. [77][78][79][80][81][82][83][84][85][86][87][88][89] Similarly, exible MoS 2 atomic layers and MoS 2 -based hybrid heterostructures have been explored for fabricating photodetectors for the next generation of wearable technologies. The progress made in developing exible MoS 2 photodetectors is summarized in this section. ...
Two-dimensional transition metal dichalcogenides have attracted much attention in the field of optoelectronics due to their tunable bandgaps, strong interaction with light and tremendous capability for developing diverse van der Waals heterostructures with other nanomaterials.
