Ultrafast Speed Research Articles

Morph-genetic bamboo-reinforced hydrogel complex for bio-mimetic actuator

Stimuli-responsive hydrogels are most promising for the fabrication of autonomous bio-mimetic soft actuators. However, their weak actuation forces and isotropic volume change hinder their practical utilization as versatile actuators, owing to their fragility. Herein, we used the morph-genetic method to fabricate anisotropic bamboo/poly(N-isopropylacrylamide) hydrogel (ABH) complex for use as soft actuator. First of all, the bamboo fiber structure provides an anisotropic framework for the ABH actuator to achieve precise deformational programmability. Secondly, benefiting from the ultra-high directional strength (110 MPa) of bamboo, ABH actuator exhibits sufficiently robust mechanical property, which generates a powerful actuating force. Lastly, owing to the regulation of bamboo sheet and PNIPAM hydrogel, the ABH actuator not only achieves ultra-fast response speed (825°/s of the bending speed), but also has excellent synergetic performance. We demonstrate several bio-mimetic actuating devices based on ABH actuator, inspired by the intricate motions of natural organisms, to highlight how the specific materials properties and their synergy can be systematically exploited for the rational design of soft actuators. Henceforth, it is anticipated that the development of hydrogel actuators could continue to benefit from the use of various naturally-anisotropic materials, such as shape-memory polymers or liquid crystals, for the preparation of further advanced hydrogel actuators by the morph-genetic method.

Ultrafast flexible PEDOT:PSS supercapacitor with outstanding volumetric capacitance for AC line filtering

Flexible supercapacitors are among the most important power supply devices for fulfilling the energy/power demands of future flexible and wearable electronics. While significant achievements have been made in improving the energy density of the flexible supercapacitors, ultrafast flexible supercapacitors remain in their infancy. Herein, an ultrafast flexible supercapacitor with outstanding capacitance is demonstrated based on the facile, one-step electropolymerization of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). In comparison to the state-of-the-art all-solid-state ultrafast flexible supercapacitors, the as-fabricated flexible PEDOT:PSS-based supercapacitor provides the highest volumetric capacitance of 38 F cm−3 in the high-frequency regime (e.g., 120 Hz) while maintaining a sufficient ultrafast response speed for 60-Hz AC line filtering applications. In addition, the electropolymerized PEDOT:PSS flexible supercapacitor provides excellent mechanical flexibility, with bending radii of 4.0–0.6 mm, and durability, with an ∼ 94% capacitance retention after 1,000 bending cycles. The high processability and outstanding electrochemical/mechanical performance are expected to contribute greatly towards the further development of high-performance ultrafast flexible supercapacitors.

Phase-Controllable Growth of Air-Stable SnS Nanostructures for High-Performance Photodetectors with Ultralow Dark Current.

The epitaxial growth of low-dimensional tin chalcogenides SnX (X = S, Se) with a controlled crystal phase is of particular interest since it can be utilized to tune optoelectronic properties and exploit potential applications. However, it still remains a great challenge to synthesize SnX nanostructures with the same composition but different crystal phases and morphologies. Herein, we report a phase-controlled growth of SnS nanostructures via physical vapor deposition on mica substrates. The phase transition from α-SnS (Pbnm) nanosheets to β-SnS (Cmcm) nanowires can be tailored by the reduction of growth temperature and precursor concentration, which originates from a delicate competition between SnS-mica interfacial coupling and phase cohesive energy. The phase transition from the α to β phase not only greatly improves the ambient stability of SnS nanostructures but also leads to the band gap reduction from 1.03 to 0.93 eV, which is responsible for fabricated β-SnS devices with an ultralow dark current of 21 pA at 1 V, an ultrafast response speed of ≤14 μs, and broadband spectra response from the visible to near-infrared range under ambient condition. A maximum detectivity of the β-SnS photodetector arrives at 2.01 × 108 Jones, which is about 1 or 2 orders of magnitude larger than that of α-SnS devices. This work provides a new strategy for the phase-controlled growth of SnX nanomaterials for the development of highly stable and high-performance optoelectronic devices.

Enhanced breakdown strength and excellent energy storage stability by B site hetero-valent doping in Sr0.7Bi0.2TiO3-based lead-free ceramic

Environment-friendly energy storage materials are embraced in global researches. Aiming at improving the energy storage performances of lead-free dielectric ceramics, the Sr0.7Bi0.2Ti(1–1.25x)NbxO3 (SBT-xN, x = 0 ∼ 0.125) lead-free ceramics were synthesized via the conventional solid state method in this work. Outstanding total energy storage density (Wtotal = 3.998 J/cm3), recoverable energy storage (Wrec = 3.43 J/cm3), and high energy storage efficiency (η of 85.84%) were obtained when x = 0.075 under the electric field of 385 kV/cm. Meanwhile, a satisfied temperature (30 ℃−110 ℃ variation less than 14%), frequency stability (10–400 Hz variation less than 1%), and anti-fatigue characteristic (107 cycles variation less than 1%) were achieved. Furthermore, the sample exhibited a remarkable discharge energy density (Wd = 3.885 J/cm3), ultrafast discharge speed (t0.9 = 73 ns), and giant discharge power density (Pd = 327.01 MW/cm3) at 400 kV/cm in charge-discharge tests. Great temperature stability (30 ℃−150 ℃ variation less than 8%) and pulse repetition frequency discharge stability (2×105 times variation less than 3.5%) were also obtained. The excellent characteristics suggest that the ceramic is a prospective candidate for advanced pulse power equipment.

SqueezeLight: A Multi-Operand Ring-Based Optical Neural Network With Cross-Layer Scalability

Optical neural networks (ONNs) are promising hardware platforms for next-generation artificial intelligence acceleration with ultrafast speed and low-energy consumption. However, previous ONN designs are bounded by one multiply–accumulate operation per device, showing unsatisfying scalability. In this work, we propose a scalable ONN architecture, dubbed <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SqueezeLight</monospace> . We propose a nonlinear optical neuron based on multioperand ring resonators (MORRs) to squeeze vector dot-product into a single device with low wavelength usage and built-in nonlinearity. A block-level squeezing technique with structured sparsity is exploited to support higher scalability. We adopt a robustness-aware training algorithm to guarantee variation tolerance. To enable a truly scalable ONN architecture, we extend <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SqueezeLight</monospace> to a separable optical CNN architecture that further squeezes in the layer level. Two orthogonal convolutional layers are mapped to one MORR array, leading to order-of-magnitude higher software training scalability. We further explore augmented representability for <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SqueezeLight</monospace> by introducing parametric MORR neurons with trainable nonlinearity, together with a nonlinearity-aware initialization method to stabilize convergence. Experimental results show that <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SqueezeLight</monospace> achieves one-order-of-magnitude better compactness and efficiency than previous designs with high fidelity, trainability, and robustness. Our open-source codes are available at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://github.com/JeremieMelo/SqueezeLight</uri> .

Nonvolatile Ferroelectric LiNbO3 Domain Wall Crossbar Memory

High-density domain wall memory based on crossbar architecture is a strong contender among next-generation high performance versatile memories due to its ultra-fast operation speed and excellent size scalability. Herein, we report 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 domain wall crossbar memory arrays fabricated on a LiNbO3 single crystal. Reversible creation and erasure of conducting domain walls between two antiparallel/parallel domains at bipolar write voltages enable the storage of digital “0” and “1” information. At the crosspoint of each word and bit lines, the memory cell can be accurately accessed, programmed and erased. The diode-like rectification of readout currents exhibited by all memory cells can inhibit read and write crosstalk. The electrical testing results in the crossbar memory array demonstrated the good stability of on/off currents and good uniformity of operating voltages, which can be reflected by the fact that the distribution of the coercive voltages is within 2.9 V and the “on”/ “off” current ratio is around 100 at a reading voltage of 3 V. Good data retention and fatigue resistance are also exhibited, making it possible to integrate domain wall random access memories in high density and reliability.

A Compact and Highly Efficient Compressive Sensing Imaging System Using In-Fiber Grating

Serial time-encoded amplified microscopy can achieve ultrafast imaging speed within varied dynamic regimes. However, it has two challenges: the high-throughput data issue and low-efficiency diffraction issue. Here, we report a compact and highly efficient ultrafast optical imaging system based on compressive sensing and in-fiber grating. Our proposal is confirmed by the proof-of-principle experiment and obtains a minimum data compression ratio of 5% with a continuous ultrafast imaging speed of 10 Mfps at a field of view of 0.5 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{\ast} 1.6$ </tex-math></inline-formula> mm. A barcode with a moving speed of 4m/s is also demonstrated for imaging and an imaging speed of 1.25 Mfps is obtained. The proposed optical imaging system overcomes the big data issue, increases energy efficiency, and paves the way for compact and highly efficient ultrafast optical imaging within dynamic scenarios.

Deep neural network for microstructured polymer fiber modeling

Microstructured polymer fibers have been widely studied for terahertz waveguides, sensing, environmental monitoring, and medicine. Time-consuming methods, including the finite element method and finite-difference time-domain, have been used to design and simulate microstructure polymer fibers. Designing optimal artificial neural networks (ANN) with various hyperparameters for each optical property considerably improve the prediction accuracy. We compared and explained the differences between predicting one quantity at one time and predicting multiple quantities at the same time. We utilized the successfully trained ANN to accurately evaluate the optical properties of the unknown geometry, including the effective refractive index (), and effective mode area (). In addition, we took logarithmic transformation to form a more uniform distribution, which allowed us to successfully predict confinement loss (α c). We also demonstrated that ANN could predict the core mode properties of unknown geometric parameters in a considerably short time compared to the finite element method simulation. Moreover, ANN with ultrafast calculation speed and high prediction accuracy accelerate the optical function device design process.

Flexible δ-MnO2 nanosheet-infixed porous carbon nanofibers for capacitive deionization

Birnessite-type manganese dioxide (δ-MnO2) is a typical pseudocapacitive material with the merits of natural abundance, environmental friendliness and high specific capacitance. Herein, the ultrathin δ-MnO2 nanosheets were successfully infixed on the electrospun porous carbon nanofibers (PCNF) by self-limitation reaction. The KMnO4 concentration and the hierarchical pore structure greatly affected the growth of δ-MnO2 nanosheets on the PCNF. Under the optimal condition, the as-prepared flexible δ-MnO2@PCNFs electrode delivered extremely high specific capacitance of 455.3 F g−1. As a cathode in capacitive deionization (CDI), δ-MnO2@PCNF presented the salt adsorption capacity of 15.9 mg g−1, with ultrafast adsorption speed (1.8 mg g−1 min−1). The δ-MnO2@PCNF materials has excellent recycling stability in CDI device due to the interconnected structure of δ-MnO2 nanosheets inserted in PCNF.

Utilizing Angle‐Dependent Photovoltage Effect in a CH3NH3PbCl3/Si Heterojunction toward High‐Performance Polarized Light Detection in Ultraviolet Region

AbstractOrganic–inorganic hybrid MAPbCl3 perovskite (MA+ = CH3NH3+) in UV photodetection is drawing interest due to its superior semiconductor properties and UV‐matchable optical bandgap. However, MAPbCl3‐based photodetector targeting high‐performance polarized light detection has remained unexplored due to the isotropic structure of MAPbCl3. The photovoltaic effect in the heterojunction, which shows an angle dependence on light polarization, provides opportunities to break the restriction of intrinsic structure for realizing polarization‐sensitive photodetection. Herein, an effective strategy is reported to realize high‐performance polarization‐sensitive UV photodetection by constructing a heterojunction with two isotropic materials MAPbCl3 and Silicon (Si). Emphatically, the photovoltage in MAPbCl3/Si heterojunction changes with the angle of polarized light with the maximum (minimum) value of 0.15 V (0.05 V), originating from the built‐in electric field. More interestingly, driven by the photovoltage, the device thus exhibits a large polarization ratio (Imax/Imin) of 2.9 at 377 nm under the self‐driven mode. Besides, the present device also delivers high‐performance photodetection in UV region owing to the superior photoresponse of MAPbCl3, including a high detectivity (D*) of 2.93 × 1011 Jones, a superior responsibility of 8 mA W–1, a substantial switching ratio of 900, and an ultrafast response speed of 40/98 µs at 0 V bias. This work opens a new avenue for high‐performance polarization‐sensitive photodetection by utilizing angle‐dependent photovoltage effect.

Programmable Polariton Topological Insulators All-Optically Controlled by the Stark Effect.

Efficiently and flexibly manipulating unidirectional edge states is key to developing topological insulators as functional devices. In this work, we propose an all-optical method that utilizes the valley-selective optical Stark effect to realize programmable topological insulators. We pattern a two-dimensional honeycomb structure in an exciton-polariton platform resulting from a strong light-matter coupling in a monolayer transition metal dichalcogenide. The optical Stark effect is induced to generate a pseudo magnetic field, combined with spin-orbit coupling to form the topological one-way edge states of the polariton. On account of the ultrafast switching speed and precisely spatial controllability of the optical Stark effect, two applications, i.e., ports ratio tunable polariton splitter and programmable polariton router, were demonstrated, showing designable and rewritable functionality of all-optically controllable polariton topological insulators. This study paves the way to robustly and intelligently control/form polaritonic and spintronic devices for future classical and quantum information processing and application.

Water-soluble Ag2S QD modified CsPbI2Br heterojunction photodetector with ultra-low dark current and ultra-fast response speed

Mixed halide inorganic perovskite CsPbI3-xBrx has attracted attention in the field of optoelectronics. As a desirable photoactive material, the application of CsPbI2Br in the field of photodetector (PD) remains to be explored. The synergistic passivation strategy based on Ag2S quantum dot (QD) aqueous solution improves the morphology of the CsPbI2Br perovskite film. At the same time, Ag2S/CsPbI2Br bulk heterojunction optimizes the energy level arrangement between perovskite and Au electrode, improves the carrier transmission and collection capacity, and thus improves the performance of PD. Ag2S/CsPbI2Br bulk heterojunction PD has an ultra-low dark current of 7.74 pA, an ultra-fast response speed of 2.95/3.07 μs, and a high switching ratio of 7.67 × 105. This work provides a method for the preparation of high-quality mixed halide perovskite materials and a strategy for the development of high-performance perovskite PDs based on bulk heterojunction.

Reconfigurable and Broadband Polarimetric Photodetector

AbstractThe sensitive detection of light polarization besides the intensity and wavelength, can provide a new degree of freedom for more and clearer information of imaging targets in night, fog, and smoke environment. However, the conventional filter‐integrated polarimetric photodetectors suffer from the complicated fabrication process and limited spectral range. Herein, broadband and polarization‐sensitive photodetectors are achieved with reconfigurable operation mode, utilizing the linear dichroism and narrow band gap of 2D As0.4P0.6 with in‐plane anisotropic structure. In As0.4P0.6‐MoTe2 heterojunction device, both photo‐gating and photovoltaic modes are operated and switchable, contributing to high responsivity (1590 A W−1 at 405 nm and 14.7 A W−1 at 1550 nm) and ultrafast speed (25 µs) in the wide spectral band (405–1550 nm). Interestingly, an optical reversal is observed on both linear dichroism and polarimetric photocurrent due to the wavelength‐dependent polarization reverse nature of the As0.4P0.6 flakes. The dichroism ratio of photocurrent can be modulated from unity to ≈10 by varying the gate voltage, enabling the reconfigurable detection mode from polarization‐independence to polarization‐susceptibility. This study demonstrates a new prototype device comprising low symmetric van der Waals heterostructure, possessing the gate‐tunability on both photo‐gain and dichroism ratio, toward high performance, reconfigurable, broadband, and polarization‐resolved photodetection and imaging applications.

Role of MXenes in advancing soft robotics.

MXenes with their unique electronic, optical, chemical, and mechanical properties have shown great promise in soft robotics. MXene-based soft actuators have been designed to display ultrafast actuations and recovery speeds as well as angle-independent structural colors in response to vapor. Several studies have developed soft actuators by combining MXenes with other materials to mimic the movement of natural organisms. Thus, MXene-based soft actuators have the potential to revolutionize the field of soft robotics and flexible electronics (e.g., wearable devices and artificial muscles). MXene-based artificial muscles have been explored for use in kinetic soft robotics as actuators in microsystems requiring exceptional compliance. MXene-based sensors and actuators have already been developed for human-like sensors and photodetection. However, there are still challenges that need to be addressed in such applications, such as the design of stretchable and compliant robotic skins with a high-level functional integration for soft robotics. The integration of various devices, such as power sources, sensors, and actuators, into soft robotics is another crucial challenge. Despite the excellent stretchability and tensile strength of MXene-based composites, there is a vital need to develop their mechanical and electrochemical features and grant them multi-functionalities. Herein, recent developments pertaining to the applications of MXenes and their composites in soft robotics are discussed with a focus on the important challenges and future perspectives.

Ultrafast Ultrasound Localization Microscopy by Conditional Generative Adversarial Network.

Ultrasound localization microscopy (ULM) overcomes the acoustic diffraction limit and enables the visualization of microvasculature at subwavelength resolution. However, challenges remain in ultrafast ULM implementation, where short data acquisition time, efficient data processing speed, and high imaging resolution need to be considered simultaneously. Recently, deep learning (DL)-based methods have exhibited potential in speeding up ULM imaging. Nevertheless, a certain number of ultrasound (US) data ( L frames) are still required to accumulate enough localized microbubble (MB) events, leading to an acquisition time within a time span of tens of seconds. To further speed up ULM imaging, in this article, we present a new DL-based method, termed as ULM-GAN. By using a modified conditional generative adversarial network (cGAN) framework, ULM-GAN is able to reconstruct a superresolution image directly from a temporal mean low-resolution (LR) image generated by averaging l -frame raw US images with l being significantly smaller than L . To evaluate the performance of ULM-GAN, a series of numerical simulations and phantom experiments are both implemented. The results of the numerical simulations demonstrate that when performing ULM imaging, ULM-GAN allows ∼40 -fold reduction in data acquisition time and ∼61 -fold reduction in computational time compared with the conventional Gaussian fitting method, without compromising spatial resolution according to the resolution scaled error (RSE). For the phantom experiments, ULM-GAN offers an implementation of ULM with ultrafast data acquisition time ( ∼0.33 s) and ultrafast data processing speed ( ∼0.60 s) that makes it promising to observe rapid biological activities in vivo.

Metal−Organic Framework-Based Ultrafast Logic Gates for High-Security Optical Encryption

Optical logic gates call for materials with giant optical nonlinearity to break the current performance bottleneck. Metal–organic frameworks (MOFs) provide an intriguing route to achieve superior optical nonlinearity benefitting from structural diversity and design flexibility. However, the potential of MOFs for optoelectronics has been largely overlooked and their applications in optical logic have not been exploited. Here, through temporally manipulating the nonlinear optical absorption process in porphyrin-based MOFs, we have successfully developed AND and XOR logic gates with an ultrafast speed approaching 1 THz and an on–off ratio above 90%. On this basis, all-optical information encryption is further demonstrated using transmittance as primary codes, which shows vast prospects in avoiding the disclosure of security information. To the best of our knowledge, this is the first exploration of MOFs for applications in ultrafast optical logic devices and information encryption.

Pulse-width-dependent optical limiting properties of a novel twist-acene compound

Organic materials with large nonlinear optical coefficient and ultrafast response speed have attracted considerable attention due to their potential applications in optical limiting (OL). However, it is a challenging obstacle to develop a candidate material with optimal nonlinear absorption response while avoiding undesirable low transmittance. Here, a novel symmetrical heteroacenes compound 4,4'-(buta-1,3-diyne-1,4-diylbis(2,7-di-tert-butyl-9,14-diphenyldibenzo[de,qr]tetracene-12,11-diyl))bis(N,N-diphenylaniline)(abbreviated as JPC-42) was synthesized and its nonlinear optical properties were investigated under different pulse-width excitation conditions at 532 nm. Results show that the compound with twisted structure displays superior optical limiting response in which extremely high transmittance (91% in 532 nm) and low OL threshold (3 × 10−3 J/cm2 in femtosecond regime, 130 × 10−3 J/cm2 in picosecond regime) are obtained. Our results demonstrate that this twist-acene compound is a promising candidate in laser protection fields.

An ultra-fast deep-learning-based dose engine for prostate VMAT via knowledge distillation framework with limited patient data

Objective. Deep-learning (DL)-based dose engines have been developed to alleviate the intrinsic compromise between the calculation accuracy and efficiency of the traditional dose calculation algorithms. However, current DL-based engines typically possess high computational complexity and require powerful computing devices. Therefore, to mitigate their computational burdens and broaden their applicability to a clinical setting where resource-limited devices are available, we proposed a compact dose engine via knowledge distillation (KD) framework that offers an ultra-fast calculation speed with high accuracy for prostate Volumetric Modulated Arc Therapy (VMAT). Approach. The KD framework contains two sub-models: a large pre-trained teacher and a small to-be-trained student. The student receives knowledge transferred from the teacher for better generalization. The trained student serves as the final engine for dose calculation. The model input is patient computed tomography and VMAT dose in water, and the output is DL-calculated patient dose. The ground-truth \\dose was computed by the Monte Carlo module of the Monaco treatment planning system. Twenty and ten prostate cases were included for model training and assessment, respectively. The model’s performance (teacher/student/student-only) was evaluated by Gamma analysis and inference efficiency. Main results. The dosimetric comparisons (input/DL-calculated/ground-truth doses) suggest that the proposed engine can effectively convert low-accuracy doses in water to high-accuracy patient doses. The Gamma passing rate (2%/2 mm, 10% threshold) between the DL-calculated and ground-truth doses was 98.64 ± 0.62% (teacher), 98.13 ± 0.76% (student), and 96.95 ± 1.02% (student-only). The inference time was 16 milliseconds (teacher) and 11 milliseconds (student/student-only) using a graphics processing unit device, while it was 936 milliseconds (teacher) and 374 milliseconds (student/student-only) using a central processing unit device. Significance. With the KD framework, a compact dose engine can achieve comparable accuracy to that of a larger one. Its compact size reduces the computational burdens and computing device requirements, and thus such an engine can be more clinically applicable.

Ultrafast extraction of uranium from seawater using photosensitized biohybrid system with bioinspired cascaded strategy

The highly effective utilization of uranium resources in global seawater is a viable method to satisfy the rising demands for fueling nuclear energy industry. Herein, inspired by the multi-mechanisms of the marine bacteria for uranium immobilization, CdS nanoparticles are deposited on the cell of marine bacterial strain Bacillus velezensis UUS-1 to create a photosensitized biohybrid system UUS-1/CdS. This system achieves high uranium extraction efficiency using a cascaded strategy, where the bacterial cells guarantee high extraction selectivity and the photosensitive CdS nanoparticles realize cascading photoreduction of high soluble U(VI) to low soluble U(IV) to enhance extraction capacity. As one of the fastest-acting adsorbents in natural seawater, a high extraction capacity for uranium of 7.03 mg g−1 is achieved with an ultrafast extraction speed of 4.69 mg g−1 d−1. The cascaded strategy promisingly improves uranium extraction performance and pioneers a new direction for the design of adsorbents to extract uranium from seawater.

High-performance Ga2O3/FTO-based self-driven solar-blind UV photodetector with thickness-optimized graphene top electrode

Self-driven solar-blind ultraviolet photodetectors (SBUVPDs) have attracted considerable interest for their superior sensitivity and operation flexibility. Herein, we demonstrate realization of a simple vertical-structured self-driven SBUVPD by pulsed laser deposition of β-Ga2O3 thin film on commercially available fluorine doped tin oxide (FTO) substrate, adopting multi-layer graphene (MLG) as the top electrode. On the one hand, the introduction of MLG with both high electrical conductance and UV transmittance greatly enhances photocurrent and responsivity of the photodetector. On the other hand, the dominating Schottky contact between Ga2O3 and MLG creates a net built-in electric field, leading to self-driven photoresponse of the device with improved response speed. With optimized thickness (8 ± 2 single layers of graphene) of the top electrode, the device exhibits the best detection performance that is superior to most of previous reports towards UV illumination at 0 V bias. It delivers a photocurrent as high as 31 nA towards 250 nm-light with ultra-fast response speed (τr = 2 ms, τd = 8.8 ms), and exhibits a maximum responsivity of 9.2 mA/W and detectivity of 5.27 × 1011 Jones under 230 nm-light illumination, while the response cuts off at light wavelength of 261 nm, falling completely within the solar blind band. In addition, the device has good multi-cycle repeatability and stability, showing great application potential in solar-blind UV detection.