Hybrid Photodetector Research Articles

Development and Performance Study of Perovskite Graphene Photodetector

Due to the lack of gain mechanism and poor light absorption ability of graphene, it is difficult for single-chip graphene photovoltaic devices to obtain high photovoltaic conversion efficiency. In view of this bottleneck, this paper aims to solve the above problems by preparing heterostructures with perovskite materials in graphene. The transfer process of graphene film was optimized to reduce the p-type doping of graphene field effect transistor and significantly improve its mobility. Polymethyl methacrylate technology is applied to the graphite process to solve the problem of channel carbonized photoresist residue in semiconductor devices. In addition, vertical graphene nanowalls (GNWs) were fabricated on Si substrates by radio frequency plasma enhanced chemical vapor deposition (RF plasma enhanced CVD), and then perovskite / GNWs hybrid photodetectors were obtained. The experimental results show that the device has high sensitivity and stable performance. In the wavelength range of 635 nm, the reaction speed of the element reaches 3.2 × 10⁵ A / W, and the response time is 24 ms (descending edge) to 8 ms.

High-performance graphene/n-Si hybrid photodetector toward self-driven optical communications

High-speed optical communication systems are built for real-time, massive, and remote information exchange; however, it is strongly reliant on the applied power. Herein, we developed a self-driven optical communication system based on a high-performance graphene/n-Si (Gr/n-Si) hybrid photodetector. Under zero bias, the Gr/n-Si device presents good performance at a wavelength of 520 nm, including the photoresponsivity of 0.27 A W−1, specific detectivity of 9.39 × 1011 Jones, and on/off ratio of 104 with a rise and fall time of 128 and 131 ns, respectively. This hybrid device also exhibits 3 dB bandwidth of 2.18 MHz as well as a small noise equivalent power of 1.68 × 10−17 W Hz−1/2. Furthermore, an optical communication system was constructed based on this hybrid photodetector, through which the audio and text signals were steadily and accurately transmitted under zero bias. Our work lays a solid foundation to demonstrate a promising application of Gr/n-Si hybrid devices toward self-driven optical communications.

Plasmonic and Graphene-Functionalized High-Performance Broadband Quasi-Two-Dimensional Perovskite Hybrid Photodetectors.

Quasi-two-dimensional (2D) layered organic-inorganic hybrid perovskites have attracted extensive attention, owing to their excellent optoelectronic tunability and moisture stability compared with three-dimensional perovskite counterparts and show great potential for application in photodetectors (PDs). However, owing to the unavoidable grain boundary defects of perovskite polycrystalline films, the photocurrent is limited by poor light absorption and charge mobility. Therefore, the preparation of quasi-2D perovskite films with strong light trapping and high charge mobility has been challenging. In this study, novel broadband quasi-2D perovskite (BA)2(FA)n-1PbnI3n+1 hybrid-structure PDs with good stability were fabricated by combining both monolayer graphene and Au square nanoarrays. The hybrid system using both graphene and Au square nanoarrays effectively improved the carrier mobility and light absorption and simultaneously maximized light trapping and light-induced carrier extraction, which resulted in PDs with greatly enhanced photocurrent in the visible and near-infrared range. The graphene-Au array-perovskite-based PDs had a low dark current of 10-10 A, large on/off ratio of 104, high responsivity of 18.71 A W-1, and detectivity of 2.21 × 1013 Jones. The responsivity and detectivity were two orders of magnitude higher than those of PDs based only on perovskites. This work demonstrates a promising and feasible device based on the coupling of a gold array, layered graphene, and quasi-2D perovskites, which shows great potential for the development of high-performance broadband perovskite PDs.

X-ray Sensitive hybrid organic photodetectors with embedded CsPbBr3 perovskite quantum dots

X-ray detection is an important technology for medical diagnosis as well as industrial and security inspections. While today's commercial X-ray detectors are bulky, photodetectors based on organic semiconductors have attracted increasing attention owing to their low temperature processing capabilities, flexibility and low cost. Nonetheless, the low X-ray attenuation coefficient of organic semiconductors still hinders their practical application. Herein, a new organic-inorganic hybrid strategy is proposed to improve the X-ray sensitivity of organic photodetectors (OPDs). A solution-processed X-ray sensitive hybrid OPD is fabricated by embedding CsPbBr 3 quantum dots (QDs) into a P3HT:PC 61 BM bulk heterojunction photodiode. The QDs, acting as embedded scintillators in the organic active layer, maintain a high radioluminescence. The proposed hybrid structure enables indirect X-ray detection in a comprehensive manner. These hybrid photodetectors exhibit suppressed dark current densities in the range of tens of picoamperes per square centimeters for different weight ratios of blended QDs. The best OPD achieves a sensitivity of 229.6 e nGy −1 mm −2 (3.67 μC Gy −1 cm −2 ) and a dark current of 23.3 pA cm −2 at a low operating voltage (−3 V) for 20–80 kV “soft” X-rays, thus representing great potential for the development of next generation low cost, portable, and highly sensitive X-ray detectors. • An all-in-one X-ray photodetector is realized by embedding CsPbBr 3 QDs into the P3HT:PC 61 BM photodiode. • The hybrid photodetectors exhibit suppressed dark current densities and high photosensitivity. • Great enhancement in X-ray sensitivity is achieved with CsPbBr 3 QDs.

Development of a hybrid photodetector device between pyruvic acid (CH3COCOOH) and silicon

The authors report on the fabrication of a pyruvic acid (Pyr)/p-Si heterojunction photodetector and analyses of electro-optical behavior of the device. First, Pyr film was coated on p-Si by spin coating method. The morphology and elemental structure of this film were determined by scanning electron microscopy and energy dispersive x-ray analysis, respectively. In order to analyze the device’s performance, the current–voltage (I–V) measurements were performed in the dark. The device was a rectification ratio of about 105 in the dark, and photodetector device parameters such as responsivity, on/off ratio and specific detectivity were analyzed in light intensity-dependent I–V measurements. Measurements depending on the light intensity were carried out between 15 and 30 mW cm−2, at 5 mW cm−2 intervals. The capacitance–voltage (C–V) and conductance–voltage (G–V) measurements carried out in the dark were analyzed at low and high frequencies in addition to the dielectric properties of the Pyr/p-Si heterojunction. Experimental results showed that the Pyr/p-Si device can be effectively applied to optical sensors and imaging devices.

Spectrum-shaped Si-perovskite hybrid photodetectors for hyperspectral bioimaging

Hyperspectral imaging (HSI) with rich spectral and spatial information holds potential for applications ranging from remote sensing to biomedicine. However, charge-coupled device (CCD) detectors used in conventional HSI systems suffer from inferior and unbalanced responsivity in the visible region, which is not a perfect choice for high-performance visible HSI. That is, conventional Si-based CCDs exhibit poor responsivity at short wavelengths (e.g., 400–600 nm) compared with that at longer wavelengths due to the nature of the indirect bandgap in silicon of around 1.1 eV. To solve this challenge, we introduce a CsPbBr 3 perovskite layer to shape the spectrum of a Si/PEDOT:PSS heterojunction photodetector (PD), resulting in a fabricated Si- CsPbBr 3 hybrid PD with enhanced responsivity at 400–600 nm. This results in an approximately flat spectral responsivity curve in the visible region (400–800 nm). Therefore, the stable Si − CsPbBr 3 hybrid PD with a flat spectrum overcomes the shortcomings of traditional Si-based PDs and makes it more suitable for HSI. Further, we set up a first perovskite HSI system with high spectrum resolution and demonstrate potential applications for tumor detection and tissue identification. We believe that this perovskite optimization can be integrated into modern CCD, thus becoming a step in future CCD fabrication processes, which is a milestone for high-performance HSI systems.

Ferroelectric Induced UV Light-Responsive Memory Devices with Low Dark Current

We developed solution-processed hybrid photodetectors with a poly (9-vinylcarbazole)/zinc oxide nanoparticle photoactive layer and a poly (vinylidene fluoride-co-trifluoroethylene) ferroelectric copolymer buffer layer on flexible plastic substrates. The presence of a ferroelectric-poling interface layer significantly enhanced the charge transfer and responsivity of the photodetectors under ultraviolet (UV, 365 nm) light exposure. The responsivity of the device reached 250 mA/W at a reverse bias of 5 V and incident light intensity of 27.5 μW/cm2. This responsivity was four times higher than that of a device without the ferroelectric copolymer layer (64 mA/W) under the same conditions. The response time of the device to incident UV light also improved from 322 to 34 ms with the addition of the ferroelectric copolymer layer. In addition, the flexible device exhibited a stable performance in an air environment up to a maximum strain of 0.3 under bending stress. Finally, a UV-light-responsive memory device was successfully fabricated by using the developed hybrid photodetector and liquid crystals. This device showed a colour change from white to black upon UV illumination, and the on-state of the device was maintained for 30 s without light exposure owing to the polarization of poly (vinylidene fluoride-co-trifluoroethylene).

Optical modulation frequency mediated tunable response time and responsivity in graphene-PbS QD based hybrid photodetectors

Graphene/lead sulfide (PbS) quantum dot (QD) hybrid infrared photodetectors have gained a lot of attention in recent times due to their high resolution and cost effective fabrication process. In spite of exhibiting remarkably high responsivity, such hybrid detectors are slow as a result of their internal gain mechanism process. In this work, we present a convenient strategy to modulate the correlation between their responsivity and response time giving access to high resolution fast photodetectors in the broadband wavelength range for imaging purpose. Using a layer-by-layer deposition technique including simultaneous ligand exchange and surface passivation at each layer, homogeneous PbS QD films on chemical vapour deposition grown single layer graphene could be achieved. The obtained hybrid phototransistors exhibit a high responsivity of 108 A W−1 and sensitivity down to 0.1 pW incident light power in the near-infrared wavelength range. By modulating the incident light at a modulation frequency up to 50 kHz, we achieve a response time as low as 5 μs while preserving a much higher responsivity (144 A W−1) compared to existing commercial room temperature infrared photodetectors.

Unfolding photophysical properties of poly(3-hexylthiophene)-MoS2 organic–inorganic hybrid materials: an application to self-powered photodetectors

Self-powered photodetectors have grown as inevitable members of the optoelectronic device family. However, it is still challenging to achieve self-powered photodetection with good responsivity in the visible spectrum region. Herein, we report solution-processable poly(3-hexylthiophene) (P3HT)-molybdenum disulfide (MoS2) organic–inorganic hybrid material, which can be used as the active layer in self-powered photodetectors. The morphological and structural properties of the synthesized P3HT-MoS2 hybrid material has been discussed using atomic force microscopy and transmission electron microscopy, respectively. The hybrid material loaded with 1 wt% MoS2 has shown an enhancement in the self-assembly of polymer in the form of fibrillar formation and excellent structural features in terms of π-conjugation. The self-powered photodetectors have been fabricated in indium tin oxide (ITO) coated glass/P3HT-MoS2/Al configuration. The merit of P3HT-MoS2 hybrid photodetectors is measured under the illumination of 470, 530, and 627 nm light in ambient conditions. P3HT-MoS2 photodetectors show significantly higher responsivity and detectivity. The photo responsivity and detectivity in P3HT-MoS2 devices are found to be 271.2 mA W−1 and 4.4 × 1010 jones at zero bias, respectively, for 470 nm light with the optical power density of 74.1 μW cm−2. Furthermore, the photocurrent switching behaviour at periodic illuminations of 1 Hz has also been examined for P3HT-MoS2 self-powered photodetectors.

Carbon Nanodots as a Potential Transport Layer for Boosting Performance of All-Inorganic Perovskite Nanocrystals-Based Photodetector

A low-cost and simple drop-casting method was used to fabricate a carbon nanodot (C-dot)/all-inorganic perovskite (CsPbBr3) nanosheet bilayer heterojunction photodetector on a SiO2/Si substrate. The C-dot/perovskite bilayer heterojunction photodetector shows a high performance with a responsivity (R) of 1.09 A/W, almost five times higher than that of a CsPbBr3-based photodetector (0.21 A/W). In addition, the hybrid photodetector exhibits a fast response speed of 1.318/1.342 µs and a highly stable photocurrent of 6.97 µA at 10 V bias voltage. These figures of merits are comparable with, or much better than, most reported perovskite heterojunction photodetectors. UV–Vis absorption and photoluminescent spectra measurements reveal that the C-dot/perovskite bilayer heterojunction has a band gap similar to the pure perovskite layer, confirming that the absorption and emission in the bilayer heterojunction is dominated by the top layer of the perovskite. Moreover, the emission intensity of the C-dot/perovskite bilayer heterojunction is less than that of the pure perovskite layer, indicating that a significant number of charges were extracted by the C-dot layer. The studied band alignment of the C-dots and perovskites in the dark and under emission reveals that the photodetector has a highly efficient charge separation mechanism at the C-dot/perovskite interface, where the recombination rate between photogenerated electrons and holes is significantly reduced. This highly efficient charge separation mechanism is the main reason behind the enhanced performance of the C-dot/perovskite bilayer heterojunction photodetector.

High-Performance Chlorophyll-b/Si Nanowire Heterostructure for Self-Biasing Bioinorganic Hybrid Photodetectors

High-Performance Chlorophyll-b/Si Nanowire Heterostructure for Self-Biasing Bioinorganic Hybrid Photodetectors

A highly responsive hybrid photodetector based on all-inorganic 2D heterojunction consisting of Cs2Pb(SCN)2Br2 and MoS2

2D perovskites recently receive significant research attention due to their unique semiconducting properties and superior stability than 3D counterparts (ABX3). In this study, a rare 2D Cs2Pb(SCN)2Br2 is prepared by partially substituting X-site halide anion with an asymmetric pseudo-halide anion, SCN-. Such 2D Cs2Pb(SCN)2X2 possess not only an all-inorganic structure but also a much smaller spacing between perovskite sheets among the reported 2D perovskites comprising large A-site organic cations. This stable 2D Cs2Pb(SCN)2Br2 is integrated with MoS2 to constitute an all-inorganic 2D heterojunction, and this all-inorganic 2D heterojunction is shown to greatly improve the performance of MoS2-based photodetector, wherein 2D Cs2Pb(SCN)2Br2 serves as light absorbing layer with regard to its intense light-harvesting property and MoS2 functions as the transport layer with regard to its remarkable electrical properties. That is, Cs2Pb(SCN)2Br2 serves as a photo-gating layer to modulate the conductive behavior of MoS2. It reveals a type-II energy band alignment formed between Cs2Pb(SCN)2Br2 and MoS2 enables efficient charge transfer from Cs2Pb(SCN)2Br2 to MoS2. Besides, Cs2Pb(SCN)2Br2 seems to passivate the surface defects on MoS2 to facilitate interfacial charge transfer. As a result, the hybrid photodetector exhibits an impressively high responsivity of 1.22 × 105 A W−1 with response time shortened to ms, among the best values reported for perovskite/MoS2 hybrid photodetectors. This encouraging result paves a new avenue for all-inorganic 2D perovskite-based optoelectronic devices.

Low-Light Photodetectors for Fluorescence Microscopy

Over the years, fluorescence microscopy has evolved and has become a necessary element of life science studies. Microscopy has elucidated biological processes in live cells and organisms, and also enabled tracking of biomolecules in real time. Development of highly sensitive photodetectors and light sources, in addition to the evolution of various illumination methods and fluorophores, has helped microscopy acquire single-molecule fluorescence sensitivity, enabling single-molecule fluorescence imaging and detection. Low-light photodetectors used in microscopy are classified into two categories: point photodetectors and wide-field photodetectors. Although point photodetectors, notably photomultiplier tubes (PMTs), have been commonly used in laser scanning microscopy (LSM) with a confocal illumination setup, wide-field photodetectors, such as electron-multiplying charge-coupled devices (EMCCDs) and scientific complementary metal-oxide-semiconductor (sCMOS) cameras have been used in fluorescence imaging. This review focuses on the former low-light point photodetectors and presents their fluorescence microscopy applications and recent progress. These photodetectors include conventional PMTs, single photon avalanche diodes (SPADs), hybrid photodetectors (HPDs), in addition to newly emerging photodetectors, such as silicon photomultipliers (SiPMs) (also known as multi-pixel photon counters (MPPCs)) and superconducting nanowire single photon detectors (SSPDs). In particular, this review shows distinctive features of HPD and application of HPD to wide-field single-molecule fluorescence detection.

Achieving a high photon count rate in digital time-correlated single photon counting using a hybrid photodetector.

We report an enhanced photon count rate in a digitally implemented time-correlated single-photon counting (TCSPC) system by utilizing a hybrid photodetector (HPD). In our digital TCSPC scheme, the photoelectronic responses from a single photon-sensitive photodetector are digitally analyzed through a high-speed analog-to-digital convertor (ADC). By virtue of the HPD which provides nearly a constant signal gain, the single-photon pulses can be effectively distinguished from pulses of simultaneously detected multiple photons by the pulse heights. Consequently, our digital TCSPC system can selectively collect single-photon signals even in the presence of intense multi-photon detections with its temporal accuracy not to be compromised. In our experiment of fluorescence lifetime measurement, the maximum count rate of single photons nearly reached the theoretical limit given by the Poisson statistics. This demonstrated that the digital TCSPC combined with the HPD provides an ultimate solution for the TCSPC implementation for high photon count rates.

Fabrication of 1D Te/2D ReS2 Mixed-Dimensional van der Waals p-n Heterojunction for High-Performance Phototransistor.

The superior optical and electronic properties of the two-dimensional (2D) rhenium disulfide (ReS2) makes it suitable for nanoelectronic and optoelectronic applications. However, the internal defects coupled with with the low mobility and light-absorbing capability of ReS2 impede its utilization in high-performance photodetectors. Fabrication of mixed-dimensional heterojunctions is an alternative method for designing high-performance hybrid photodetectors. This study proposes a mixed-dimensional van der Waals (vdW) heterojunction photodetector, containing high-performance one-dimensional (1D) p-type tellurium (Te) and 2D n-type ReS2, developed by depositing Te nanowires on ReS2 nanoflake using the dry transfer method. It can improve the injection and separation efficiency of photoexcited electron-hole pairs due to the type II p-n heterojunction formed at the ReS2 and Te interface. The proposed heterojunction device is sensitive to visible-light sensitivity (632 nm) with an ultrafast photoresponse (5 ms), high responsivity (180 A/W), and specific detectivity (109), which is superior to the pristine Te and ReS2 photodetectors. As compared to the ReS2 device, the responsivity and response speed is better by an order of magnitude. These results demonstrate the fabrication and application potential of Te/ReS2 mixed-dimensional heterojunction for high-performance optoelectronic devices and sensors.

High-Responsivity Solar-Blind Ultraviolet Photodetectors Based on Carbon Nanodots/Graphene Hybrids

The intrinsically poor optical absorption and short carrier lifetime of graphene have restricted its practical application in photodetectors. Carbon nanodots (CNDs) have received much attention due to their fascinating optical properties, environmentally friendly nature, small size, and superiority of a large optical absorptivity. Thus, in this article, a hybrid photodetector based on CNDs and graphene has been proposed for the solar-blind ultraviolet (UV) photodetection, in which CNDs were integrated with graphene to form a hybrid structure which was capable of detecting UV light with 254 nm. Here, this article also demonstrated that a high photoresponsivity of ~433.33 A/W and a detectivity of ~1.08 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> Jones can be obtained in the hybrid photodetector. UV illumination causes photogenerated electrons and holes in CNDs. Holes transfer to graphene and then recirculate many times, which originates from the high carrier mobility of graphene and the prolonged lifetime of excited electrons that remain trapped in CNDs. Our result demonstrates that the integration of graphene and CNDs shows better optical absorption and wavelength selectivity. Together with the mechanism, it paves a step for practical applications of quantum dots sensitized graphene-based photodetectors.

Perovskite/Silicon‐Nanowire‐Based Hybrid Heterojunctions for Fast and Broadband Photodetectors

A hybrid photodetector fabricated with a halide perovskite and silicon nanowire (SiNW) heterojunction for broadband detection ranging from near‐ultraviolet to near‐infrared is reported. The device fabrication is conducted by directly coating chemically etched vertical SiNW arrays with perovskite thin films and nanofibers produced from liquid precursors. The optimized perovskite thin film/SiNW heterojunction‐based device under 532 nm illumination exhibits excellent spectral responsivity of 13 A W−1, high specific detectivity reaching 1013 Jones at 0.3 V external bias, and fast rise/fall times of 22.2/17.6 μs. The device shows very good stability under ambient conditions, even after 30 days of storage. Overall, this simple, all‐solution‐based hybrid photodetector offers great potential for the future integrated optoelectronic devices.

High-performance graphene/Si hybrid photodetector with a PMMA coating layer

Photodetectors with ultrahigh responsivity are meaningful for weak optical signal detection in the fields of biomedicine science and environmental monitoring. Graphene/Si hybrid photodetectors with ultrahigh photoresponsivity have already been reported. However, with all atoms exposed to the environment, graphene-based devices often show low stability. Here, the PMMA layer assisting the graphene transfer process has been retained on the surface of graphene during the fabrication process of the graphene/Si hybrid photodetector, and a high stability graphene photodetector with ultrahigh responsivity (>106 A W−1 for white LED illumination) has been successfully demonstrated. The fabricated graphene/Si hybrid photodetectors may have the potential to be utilized in functional near-infrared spectroscopy systems or underwater wireless optical communication systems for weak optical signal detection.

A High‐Performance Flexible Broadband Photodetector Based on Graphene–PTAA–Perovskite Heterojunctions

AbstractOrganometal halide perovskites (CH3NH3PbI3−xClx) have received considerable attention in the field of optoelectronics due to their strong light absorption and long carrier lifetime. However, the performance such as response speed, responsivity, and stability of such detectors still need to be improved. In this paper, a flexible photodetector (PD) composed of multilayered structure of graphene–poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA)–perovskite‐poly(methyl methacrylate) (PMMA) is proposed. The PD can detect a wide wavelength range from ultraviolet to near infrared. The PD shows a high detectivity of ≈1013 Jones and a responsivity of 105 A W−1 at 360 nm. More importantly, the device also shows a high bending durability, fast response time, and good stability in air due to the protection of the PMMA layer. The facile and low‐cost fabrication of the flexible perovskite‐based hybrid photodetector indicates the mass production for the potential application in sensitive broadband photodetection.

Graphene/SrTiO3 interface-based UV photodetectors with high responsivity* *Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFF0104801 and 2018YFB0406601) and the National Natural Science Foundation of China (Grant Nos. 61804012 and 11721404).

Strontium titanate (SrTiO3), which is a crucial perovskite oxide with a direct energy band gap of 3.2 eV, holds great promise for ultraviolet (UV) photodetection. However, the response performance of the conventional SrTiO3-based photodetectors is limited by the large relative dielectric constant of the material, which reduces the internal electric field for electron-hole pair separation to form a current collected by electrodes. Recently, graphene/semiconductor hybrid photodetectors by van-der-Waals heteroepitaxy method demonstrate ultrahigh sensitivity, which is benefit from the interface junction architecture and then prolonged lifetime of photoexcited carriers. Here, a graphene/SrTiO3 interface-based photodetector is demonstrated with an ultrahigh responsivity of 1.2 × 106 A/W at the wavelength of 325 nm and ∼ 2.4 × 104 A/W at 261 nm. The corresponding response time is in the order of ∼ ms. Compared with graphene/GaN interface junction-based hybrid photodetectors, ∼ 2 orders of magnitude improvement of the ultrahigh responsivity originates from a gain mechanism which correlates with the large work function difference induced long photo-carrier lifetime as well as the low background carrier density. The performance of high responsivity and fast response speed facilitates SrTiO3 material for further efforts seeking practical applications.