Self-powered Photodetector Research Articles

Van der Waals Schottky Junction Photodetector with Ultrahigh Rectifying Ratio and Switchable Photocurrent Generation.

Metal-semiconductor junctions play an important role in the development of electronic and optoelectronic devices. A Schottky junction photodetector based on two-dimensional (2D) materials is promising for self-powered photodetection with fast response speed and large signal-to-noise ratio. However, it usually suffers from an uncontrolled Schottky barrier due to the Fermi level pinning effect arising from the interface states. In this work, all-2D Schottky junctions with near-ideal Fermi level depinning are realized, attributed to the high-quality interface between 2D semimetals and semiconductors. We further demonstrate asymmetric diodes based on multilayer graphene/MoS2/PtSe2 with a current rectification ratio exceeding 105 and an ideality factor of 1.2. Scanning photocurrent mapping shows that the photocurrent generation mechanism in the heterostructure switches from photovoltaic effect to photogating effect at varying drain biases, indicating both energy conversion and optical sensing are realized in a single device. In the photovoltaic mode, the photodetector is self-powered with a response time smaller than 100 μs under the illumination of a 405 nm laser. In the photogating mode, the photodetector exhibits a high responsivity up to 460 A/W originating from a high photogain. Finally, the photodetector is employed for single-pixel imaging, demonstrating its high-contrast photodetection ability. This work provides insight into the development of high-performance self-powered photodetectors based on 2D Schottky junctions.

Visible-Light Self-Powered Photodetector with High Sensitivity Based on the Type-II Heterostructure of CdPSe3/MoS2.

Transition metal thiophosphates (MTPs) are a group of emerging van der Waals materials with widely tunable band gaps. In the MTP family, CdPSe3 is demonstrated to possess a wide energy band gap and high carrier mobility, making it a potential candidate in optoelectronic applications. Here, we reported photoelectric response behaviors of both CdPSe3- and CdPSe3/MoS2-based photodetectors (noted as CPS and CM, respectively); these showed prominent photoelectric performances, and the latter proved to be significantly superior to the former. These devices exhibited ultralow dark current at a magnitude order of 10-12 A and fine cycle and air stabilities. Compared with CPS, CM demonstrated the highest responsivity (91.12 mA/W) and detectivity (1.74 × 1011 Jones) at 5 V under 425 nm light illumination. Besides, CM showed self-powered photoelectric responses at zero bias, which was attributed to the improved separation efficiency of photogenerated carriers by the built-in electric field at the interface of the p-n junction. This work proves a prospect for the CM device in portable, self-powered optoelectronic device applications.

Self-Rolled-Up WSe2 One-Dimensional/Two-Dimensional Homojunctions: Enabling High-Performance Self-Powered Polarization-Sensitive Photodetectors.

Mixed-dimensional heterostructures integrate materials of diverse dimensions with unique electronic functionalities, providing a new platform for research in electron transport and optoelectronic detection. Here, we report a novel covalently bonded one-dimensional/two-dimensional (1D/2D) homojunction structure with robust junction contacts, which exhibits wide-spectrum (from the visible to near-infrared regions), self-driven photodetection, and polarization-sensitive photodetection capabilities. Benefiting from the ultralow dark current at zero bias voltage, the on/off ratio and detectivity of the device reach 1.5 × 103 and 3.24 × 109 Jones, respectively. Furthermore, the pronounced anisotropy of the WSe2 1D/2D homojunction is attributed to its low symmetry, enabling polarization-sensitive detection. In the absence of any external bias voltage, the device exhibits strong linear dichroism for wavelengths of 638 and 808 nm, with anisotropy ratios of 2.06 and 1.96, respectively. These results indicate that such mixed-dimensional structures can serve as attractive building blocks for novel optoelectronic detectors.

High-quality lateral monolayer-multilayer graphene junction formed by selective laser thinning for self-powered photodetection

The formation of an asymmetric junction is key to graphene-based photodetectors of high-sensitive photodetectability, because such a junction can not only facilitate the diffusion or drift of photogenerated carriers but also realize a self-powered operation. Here, a monolayer-multilayer graphene junction photodetector is accomplished by selectively thinning part of a multilayer graphene to a high-quality monolayer. Benefiting from the large photoabsorption cross section of multilayer graphene and strong asymmetry caused by the significant differences in optoelectronic properties between monolayer and multilayer graphene, the monolayer-multilayer graphene junction shows a 7-fold increase in short-circuit photocurrent as compared with that at the monolayer graphene-metal contact in scanning photocurrent images. The asymmetric configuration also enables the photodetector to work at zero bias with minimized dark current noise and stand-by power consumption. Under global illumination with visible light, a photoswitching ratio of 3.4 × 103, a responsivity of 8.8 mA W−1, a specific detectivity of 1.3 × 108 Jones and a response time of 11 ns can be obtained, suggesting a promising photoresponse. Moreover, it is worth mentioning that such a performance enhancement is achieved without compromising the broadband spectral response of graphene photodetector and it is hence applicable for long wavelength spectral range including infrared and terahertz.

CVD-Grown Monolayer MoS2 and GaN Thin Film Heterostructure for a Self-Powered and Bidirectional Photodetector with an Extended Active Spectrum.

Photodetector technology has evolved significantly over the years with the emergence of new active materials. However, there remain trade-offs between spectral sensitivity, operating energy, and, more recently, an ability to harbor additional features such as persistent photoconductivity and bidirectional photocurrents for new emerging application areas such as switchable light imaging and filter-less color discrimination. Here, we demonstrate a self-powered bidirectional photodetector based on molybdenum disulfide/gallium nitride (MoS2/GaN) epitaxial heterostructure. This fabricated detector exhibits self-powered functionality and achieves detection in two discrete wavelength bands: ultraviolet and visible. Notably, it attains a peak responsivity of 631 mAW-1 at a bias of 0V. The device's response to illumination at these two wavelengths is governed by distinct mechanisms, activated under applied bias conditions, thereby inducing a reversal in the polarity of the photocurrent. This work underscores the feasibility of self-powered and bidirectional photocurrent detection but also opens new vistas for technological advancements for future optoelectronic, neuromorphic, and sensing applications.

Solution processed CuInS2/SnO2 heterojunction based self-powered photodetector for UV encrypted visible light communication

A photodetector (PD) featuring dual-band detection capability and self-powering attributes is crucial for various applications in sensing, communication, and imaging. Here, we present a self-powered PD based on a solution-processed CuInS2/SnO2 heterojunction capable of detecting ultraviolet (UV) and visible light spectra. The CuInS2 layer was composed of ∼2 nm-sized quantum dots (QDs) synthesized using the hot injection method, while the SnO2 layer was fabricated using a straightforward sol-gel technique. This self-powered PD displayed a significant spectral response across both UV (355 nm) and visible light (532 nm) ranges, all accomplished without the need for external bias. The PD demonstrates rapid detection, with rise and decay times of 125 ms and 156ms for visible light and 85 ms and 200 ms for UV light, respectively, at a power level of 15 mW. The PD achieved responsivity values of 10.66 μA/W and 34.56 μA/W for visible and UV light, respectively. The impressive capability for dual-band detection in both ultraviolet (UV) and visible light showcases the practical feasibility and utility of this device for self-powered photodetection and deciphering UV-encrypted visible light communication. Moreover, its straightforward solution-based processing attribute renders it valuable for the mass production of devices and technology.

Enhanced Performance of Self-Powered Solar-Blind Deep UV Photodetectors Based on ZnGa2O4/Ga2O3 Heterojunctions

Enhanced Performance of Self-Powered Solar-Blind Deep UV Photodetectors Based on ZnGa₂O₄/Ga₂O₃ Heterojunctions

High Performance Deep Ultraviolet p-i-n Self-Powered Photodetector Based on p-NiO/i-β-Ga₂O₃/n-β-Ga₂O₃ With Controlled a Fermi Level and Used an Intrinsic β-Ga₂O₃ Layer

High Performance Deep Ultraviolet p-i-n Self-Powered Photodetector Based on p-NiO/i-β-Ga₂O₃/n-β-Ga₂O₃ With Controlled a Fermi Level and Used an Intrinsic β-Ga₂O₃ Layer

High Performance Self-Powered Photodetectors Based on Graphene Nanoribbons/Al2O3/InGaZnO Heterojunctions

High Performance Self-Powered Photodetectors Based on Graphene Nanoribbons/Al₂O₃/InGaZnO Heterojunctions

Self-Powered and Broadband Photodetector with High Responsivity and Fast Response Based on La-Doped PbSe Film Heterojunction

Self-Powered and Broadband Photodetector with High Responsivity and Fast Response Based on La-Doped PbSe Film Heterojunction

Self-powered poly(3-hexylthiophene)/ZnO heterojunction ultraviolet photodetectors decorated by silver nanoparticles

Self-powered poly (3-hexylthiophene)/zinc oxide (P3HT/ZnO) heterojunction ultraviolet photodetectors decorated by silver nanoparticles (Ag NPs) were fabricated by sol-gel and spin-coating techniques. The ultraviolet photoresponse performance of the P3HT/ZnO heterojunction photodetectors influenced by the position of plasmonic Ag NPs was investigated. The responsivity and detectivity of the P3HT/Ag/ZnO photodetector with placed Ag NPs at the interface of ZnO and P3HT layers enhanced to 1.92 and 1.15 times compared to the reference devices. When the Ag NPs embedded into ZnO layer, the responsivity, detectivity and external quantum efficiency were 16.42 mA/W, 5.97 × 1011 Jones, and 5.36 %, respectively, which were 5.77 times, 4.64 times and 5.77 times to that of the pristine P3HT/ZnO photodetector. The enhancement mechanism of plasmonic metallic nanoparticles to the performance of the photodetectors was discussed in details. This study presents a simple route to high performance self-powered photodetectors.

Wavelength-modulated polarity switch self-powered Bi2Se3/GaN heterostructure photodetector

Van der Waals and wide-bandgap materials-based heterostructures have garnered substantial attention in developing self-powered broadband photodetectors owing to their exceptional photovoltaic capabilities. These materials also hold great potential for breakthroughs in optoelectronics. However, limitations to low selectivity constrain the potential of heterostructures-based broadband detectors. Here, we design wavelength-selective polarity switching in a heterostructure photodetector consisting of bismuth selenide (Bi2Se3) and gallium nitride (GaN). The analysis revealed a positive photocurrent under ultraviolet-C illumination to visible wavelength, whereas a negative photocurrent under infrared wavelengths at zero applied bias. The exposure to distinct optical wavelengths leads to an inversion in the electric field polarity across the junction, resulting in polarity switching. The fabricated Bi2Se3/GaN self-powered ultra-broadband photonic device demonstrates a peak photoresponsivity of 584 mAW−1 (−297 mAW−1) at 355 nm (1405 nm) wavelength illumination and can detect weak signals up to 650 femto-watt. Our strategy revealed alternative avenues for developing polarity-switchable, self-powered ultra-broadband photodetectors, offering a first step towards creating wavelength-adaptable sensors for future applications.

Realizing Ultrafast Response Speed for Self-Powered Photodetectors with a Molecular-Doped Lateral InSe Homojunction.

The implementation of energy-saving policies has stimulated intensive interest in exploring self-powered optoelectronic devices. The 2D p-n homojunction exhibits effective generation and separation of carriers excited by light, realizing lower power consumption and higher performance photodetectors. Here, a self-powered photodetector with high performance is fabricated based on an F4-TCNQ localized molecular-doped lateral InSe homojunction. Compared with the intrinsic InSe photodetector, the switching light ratio (Ilight/Idark) of the p-n homojunction device can be enhanced by 2.2 × 104, and the temporal response is also dramatically improved to 24/30 μs. Benefiting from the built-in electric field, due to the formation of an InSe p-n homojunction after partial doping of F4-TCNQ on InSe, the device possesses a high responsivity (R) of 93.21 mA/W, with a specific detectivity (D*) of 1.14 × 1011 Jones. These results suggest a promising approach to get a lateral InSe p-n homojunction and reveal the potential application of the device for next generation low-consumption photodetectors.

Highly Responsive and Self-Powered Photodetector Based on PtSe2/MoS2 Heterostructure.

In recent years, 2D materials and their heterostructures have started to offer an ideal platform for high-performance photodetection devices. In this work, a highly responsive, self-powered photodetector based on PtSe2/MoS2 van der Waals heterostructure is demonstrated. The device achieves a noteworthy wide band spectral response from visible (405 nm) range to the near infrared region (980 nm). The remarkable photoresponsivity and external quantum efficiency up to 4.52 A/W, and 1880% are achieved, respectively, at 405 nm illumination with fast response time of 20 ms. In addition, the photodetector exhibits a decent photoresponsivity of 33.4 mA/W at zero bias, revealing the photodetector works well in the self-driven mode. Our work suggests that a PtSe2/MoS2 heterostructure could be a potential candidate for the high-performance photodetection applications.

Photoelectrochemical properties of self-powered corundum-structured Ga2O3 nanorod array/fluorine-doped SnO2 photodetectors modulated by precursor concentrations

Herein, corundum-structured Ga2O3 (α-Ga2O3) nanorod array/fluorine-doped SnO2 (FTO) structures have been fabricated by hydrothermal and thermal annealing processes with different precursor concentrations from 0.01 to 0.06 M. The diameter and length of the nanorod arrays are much larger with increasing precursor concentrations due to more nucleation sites and precursor ions participating in the reaction procedures. The optical bandgap decreases from 4.75 to 4.47 eV because of the tensile stress relieving with increasing the precursor concentrations. Based on self-powered photoelectrochemical (PEC) photodetectors, the peak responsivity is improved from ∼0.33 mA W−1 for 0.06 M to ∼1.51 mA W−1 for 0.02 M. Schottky junctions can be formed in PEC cells. More photogenerated carriers can be produced in wider depletion region. From Mott–Schottky plots, the depletion regions become much wider with decreasing the precursor concentrations. Therefore, the enhance responsivity is owing to the wider depletion regions. Due to the reduced possibility of photogenerated holes captured by traps ascribed from fewer green and yellow luminescence defects, smaller charge transfer resistance, and shorter transportation route, the decay time becomes much faster through decreasing the precursor concentrations. Compared with the other self-powered α-Ga2O3-nanorod-array-based PEC photodetectors, it shows the fastest response time (decay time of 0.005 s/0.026 s) simply modulated by precursor concentrations for the first time without employing complex precursors, seed layers or special device designs. Compared with other high-responsivity monoclinic Ga2O3 (β-Ga2O3) self-powered photodetectors, our devices also show comparable response speed with simple control and design. This work provides the realization of fast-speed self-powered Ga2O3 based solar-blind ultraviolet photodetectors by simple modulation processes and design, which is a significant guidance for their applications in warnings, imaging, computing, communication and logic circuit, in the future.

Enhanced Light Trapping in ZnO Nanowire Arrays/NiO Heterojunction for Self-Powered Photodetection

Enhanced Light Trapping in ZnO Nanowire Arrays/NiO Heterojunction for Self-Powered Photodetection

Fabrication of Al doped α-GaOOH nanorod arrays on FTO for self-powered photoelectrochemical solar-blind UV photodetectors

Al doped α-GaOOH nanorod arrays were grown on FTO via hydrothermal processes by using gallium nitrate and aluminum nitrate mixed aqueous solutions with fixed 1:1 mole ratio as precursors. With increasing the gallium nitrate precursor concentrations, the Ga/Al atom ratios in nanorod arrays increase from 0.36 to 2.08, and the length becomes much longer from 650 nm to 1.04 μm. According to the binding energy difference between Ga 2p3/2 core level and its background in x-ray photoelectron spectroscopy, the bandgap is estimated to be around 5.3 ± 0.2 eV. Al doped α-GaOOH nanorod array/FTO photoelectrochemical photodetectors show enhanced self-powered solar-blind UV photodetection properties, with the decrease of Ga precursor concentrations. The maximum responsivity at 255 nm is 0.09 mA W−1, and the fastest response time can reach 0.05 s. The improved photoresponse speed is ascribed from much shorter transportation route, accelerated carrier recombination by recombination centers, and smaller charge transfer resistance at the α-GaOOH/electrolyte interface with decreasing the gallium nitrate precursor concentrations. The stability and responsivity should be further improved. Nevertheless, this work firstly demonstrates the realization of self-powered solar-blind UV photodetection for α-GaOOH nanorod arrays on FTO via Al doping.

Monolithically grown CSPbBr3 by chemical vapor deposition for Self-Powered photodetector

The high-quality monolithic growth of perovskite films with larger grains on any substrate is a challenging task due to the instability of morphology, carrier mobility and chemical stability. In this work, we demonstrated the strategy to grow CsPbBr3 films with micron-sized grains along the (002) surface by chemical vapor deposition. The structural and optical characterizations have shown that the as-grown CsPbBr3 thin films are compact and packed without pin holes and have excellent optical quality for use in high-performance optoelectronic devices. The planar photodetector with the device configuration Ag/CsPbBr3/Ag shows a high photoresponsivity of 506.32 A/W and a specific detectivity of 8.29 × 1012 Jones at an incident light illumination of 22.3 µW/cm2. On the other hand, the vertically stacked device with ITO/SnO2/CsPbBr3/CuSCN/Ag configuration exhibits a photoresponsivity of 10.13 A/W at 0.05 V bias and 96 mA/W under 0 V bias. Specifically, the response time of the device in planar geometry is 241/205 ms, while the vertically stacked device has a response time of 20.51/21 ms at 0.05 V bias and 20.51/30 ms at 0 V bias. The results provide a new strategy for the growth of high-quality perovskite thin films and their effective application for high-performance optoelectronic devices.

V2O5 nanoflakes for broad-spectral-response self-powered photodetectors with a high on/off ratio and high detectivity

In this study, V2O5 nanoflakes (NFs) was coated on Si substrate by DC sputtering to obtain V2O5 NFs/n-Si heterojunction. To utilize V2O5 NFs as a broadband photodetector, absorbance spectra were studied using UV−Vis−near-IR spectroscopy. Cut-off wavelength was 530 nm. Furthermore, energy dispersive x-ray, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and scanning electron microscope analyses of V2O5 NFs were achieved. The V2O5 NFs/n-Si device gave a very high rectifying ratio of 1.18 × 104 in the dark and at zero bias, it has self-powered mode and an on/off ratio of 1.29 × 106. Optical analyses of the V2O5 NFs/n-Si heterojunction device were studied in detail under UV (365, 395 nm) and IR (850 nm) illumination as well as visible light with varying light intensities. Analysis of experimental studies showed that the device has a high photoresponse under all illuminations. For optical analysis based on I–V measurements, responsivity, detectivity, on/off ratio, external quantum efficiency (EQE), normalized photocurrent-dark-current ratio and noise-equivalent power (NEP) analyses were achieved. The maximum values of responsivity from measurements under visible, UV (395 nm) and IR illumination (850 nm) were 104, 882 and 850 mA W−1 for −2.0 V, respectively. Detectivity values are maximized at V = 0 V and are 6.84 × 1011, 7.87 × 1012 and 6.87 × 1012Jones for the same illuminations respectively. With increasing intensity, the rectification ratio and NEP decreased while the other parameters generally increased. The increase in performance at increasing visible intensity was attributed to the increase in photogenerated carrier density at high intensities, and the high performance in the UV region was attributed to the high light absorption of V2O5 NFs in the UV region.

Enhancing performance of SnS2 based self-powered photodetector and photocatalyst by Na incorporation

Sn and S are environmentally friendly elements that are abundant in nature. The SnS2 compound formed with these elements has intrinsic n-type electrical conductivity and a direct forbidden band gap of ∼2.2 eV. Therefore, it is a very promising compound for visible light optoelectronic applications. In this study, SnS2thin films were coated on p-Si substrates and pn heterojunction structures were obtained. By adding certain amounts of Na element to SnS2, the photosensitivity of the heterojunction devices increased tremendously and reached a high value of 3.2 × 104 under zero bias condition. It was observed that the prepared devices had excellent speeds and stability with rise and decay times of as low as 28 m s and 23 m s. Moreover, the devices were found to be sensitive to visible light even at ultra-low light intensity of ∼0.3 μW/cm2. Furthermore, the responsivity and specific detectivity values of the prepared photodetectors reach very high values of 11 A/W and 8.4 × 1013 Jones at this low light intensity. The NEP value drops to a low level of 2.7 × 10−15 WHz −1/2. In addition, the photocatalytic properties of Na-doped and undoped SnS2 compound were also examined under visible LED light. Compared to undoped samples, photocatalytic efficiency increased by ∼42 % in Na-doped SnS2 thin films. The findings clearly reveal that Na improves both photodetector device performance and the photocatalytic effect of the SnS2 semiconductor.