Photoelectric Response Research Articles

Layer symmetry and irradiation dominate the oxidation capability of birnessite on biogenic isoprene.

The climate-active gas isoprene (C5H8) is one of the most abundant biogenic volatile organic compounds (VOCs). Soil is one of the significant sinks for isoprene, yet the role played by the naturally abundant birnessite in the soil surface layer during the oxidation of isoprene remains largely unknown. This study investigates the reactions of isoprene with triclinic and hexagonal birnessite on the Earth's surface environments. Hexagonal birnessite exhibits a superior oxidation capacity than triclinic birnessite, rapidly oxidizing isoprene. The transformation of birnessite from triclinic to hexagonal increases the number of interlayer Mn(III) octahedra, which creates numerous sites for isoprene oxidation. In-situ DRIFTS and DFT calculations indicate that abundant electrophilic active species on the surface of hexagonal birnessite, such as interlayer Mn(III) octahedra and 1O2, oxidize isoprene by attacking conjugated double bonds. Furthermore, birnessite exhibits excellent photoelectric response and photothermal effects, enabling sunlight irradiation under natural conditions to accelerate the oxidation of isoprene by birnessite. The findings of this study elucidates the critical role of birnessite in the oxidation of isoprene and shed light on the fate of isoprene in soil minerals.

Theoretical Study of the Magnetic Mechanism of a Pca21 C4N3 Monolayer and the Regulation of Its Magnetism by Gas Adsorption

For metal-free low-dimensional ferromagnetic materials, a hopeful candidate for next-generation spintronic devices, investigating their magnetic mechanisms and exploring effective ways to regulate their magnetic properties are crucial for advancing their applications. Our work systematically investigated the origin of magnetism of a graphitic carbon nitride (Pca21 C4N3) monolayer based on the analysis on the partial electronic density of states. The magnetic moment of the Pca21 C4N3 originates from the spin-split of the 2pz orbit from special carbon (C) atoms and 2p orbit from N atoms around the Fermi energy, which was caused by the lone pair electrons in nitrogen (N) atoms. Notably, the magnetic moment of the Pca21 C4N3 monolayer could be effectively adjusted by adsorbing nitric oxide (NO) or oxygen (O2) gas molecules. The single magnetic electron from the adsorbed NO pairs with the unpaired electron in the N atom from the substrate, forming a Nsub-Nad bond, which reduces the system’s magnetic moment from 4.00 μB to 2.99 μB. Moreover, the NO adsorption decreases the both spin-down and spin-up bandgaps, causing an increase in photoelectrical response efficiency. As for the case of O2 physisorption, it greatly enhances the magnetic moment of the Pca21 C4N3 monolayer from 4.00 μB to 6.00 μB through ferromagnetic coupling. This method of gas adsorption for tuning magnetic moments is reversible, simple, and cost-effective. Our findings reveal the magnetic mechanism of Pca21 C4N3 and its tunable magnetic performance realized by chemisorbing or physisorbing magnetic gas molecules, providing crucial theoretical foundations for the development and utilization of low-dimensional magnetic materials.

First-principles studies of strain-tunable InN monolayer: Applications for switching and optoelectronic devices

Abstract Two-dimensional (2D) materials are attracting significant attention for their potential applications in the post-Moore era. In this work, we systematically investigate the effect of strains on the electronic structure, transport and optoelectronic properties of 2D indium nitride (InN) monolayer using density functional theory and non-equilibrium Green’s function methods. The results show that strains can modulate the electronic properties. Specifically, biaxial strain triggers the transition from semiconductor to metal and indirect to direct band gap. On this basis, the constructed InN-based nanodevice exhibits current switching ratios up to 10^10. In addition, the optoelectronic device based on InN monolayer exhibits a robust photoelectric response in the red light. Meanwhile, biaxial strain can improve the optoelectronic performance of InN-based optoelectronic devices. The compressive strains blue-shift the photocurrent peaks of the InN monolayer, which effectively modulates its detection range in the visible light region. These findings underscore the potential applications in nanotechnology, particularly in nano-switches and optoelectronic devices.

Improving photoexcited carrier separation through Z-scheme W18O49/BiOBr heterostructure coupling carbon quantum dots for efficient photoelectric response and tetracycline photodegradation

Building Z-scheme heterostructure integrating oxygen vacancies seems to effectively encourage photoexcited charge partition and hence photoelectric response and photocatalytic performance. Here, through the inclusion of carbon quantum dots (CQDs) with W18O49/BiOBr (WB) for enhancing electron exchange and band structure control, we have developed one Z-scheme ternary CQD/W18O49/BiOBr heterostructures (CWB) with intense oxygen vacancies. The optimal CWB heterostructure shows superior photocatalytic and photoelectric response execution. The findings indicate that CWB has higher photocatalytic degradation efficiency of tetracycline hydrochloride (TC) at 97 % compared to WB or W18O49 alone. Additionally, the CWB shows a higher photocurrent density, surpassing WB and W18O49 by 2.5 times and 5.4 times. A potential self-supplied photoelectrochemical-type photodetector utilizing CWB displays relatively quick and stable photoelectric response at 0 V. The improved photo-electric performance are linked to the combined impact of separation and redistribution of charges caused by Z-scheme heterostructure and oxygen vacancies, as well as intensive light absorbance by localized surface plasmon resonance. Our research also validates significance of CQDs as cocatalyst in accelerating the splitting of photo carriers in Z-scheme ternary CWB heterostructures, which will stimulate interest in creating advanced photoactive heterojunction substance with carbon nanomaterials.

Effects of Black Silicon Surface Morphology Induced by a Femtosecond Laser on Absorptance and Photoelectric Response Efficiency

In this study, the effects of variations in the height (h) and bottom radius (r) of black silicon microstructures on their absorptance and photoelectric response efficiency were analyzed. By using the relation cot⁡θ2=hr to combine the parameters, it was found that changes in morphology affected the absorptance of black silicon microstructures, with h being directly proportional to the absorptance, while r was inversely proportional. A positive correlation was observed between cot⁡θ2 and absorptance. However, the correlation between cot⁡θ2 and photoelectric response efficiency was not significant. Through Raman spectroscopy analysis of the samples, it was concluded that as the laser ablation energy density increased, more lattice defects were introduced, weakening the charge carrier transport efficiency. This study further elucidated the mechanism by which microstructural changes impacted the absorptance and energy density of black silicon, providing valuable insights for optimizing its energy density.

Sensitive SWIR Organic Photodetectors with Spectral Response Reaching 1.5µm.

The performance of organic photodetectors (OPDs) sensitive to the short-wavelength infrared (SWIR) light lags behind commercial indium gallium arsenide (InGaAs) photodetectors primarily due to the scarcity of organic semiconductors with efficient photoelectric responses exceeding 1.3µm. Limited by the Energy-gap law, ultralow-bandgap organic semiconductors usually suffer from severe non-radiative transitions, resulting in low external quantum efficiency (EQE). Herein, a difluoro-substituted quinoid terminal group (QC-2F) with exceptionally strong electron-negativity is developed for constructing a new non-fullerene acceptor (NFA), Y-QC4F with an ultralow bandgap of 0.83eV. This subtle structural modification significantly enhances intermolecular packing order and density, enabling an absorption onset up to 1.5µm while suppressing non-radiation recombination in Y-QC4F films. SWIR OPDs based on Y-QC4F achieve an impressive detectivity (D*) over 1011 Jones from 0.4 to 1.5µm under 0V bias, with a maximum of 1.68 × 1012 Jones at 1.16µm. Furthermore, the resulting OPDs demonstrate competitive performance with commercial photodetectors for high-quality SWIR imaging even under 1.4µm irradiation.

Modulating d-p-band electron coupling by N-doping for promoting CuSAs-N/TiO2 photocatalytic hydrogen evolution

Doping can effectively improve the light absorption of single-atoms photocatalysts, but the metal-support interaction (MSI) and surface electronic structure will change due to doping, which needs further study. Herein, we report a nano-TiO2 co-modified with internal doping of N and surface loading of Cu single atoms (CuSAs-N/TiO2) for photocatalytic water-splitting hydrogen evolution. Experimental and theoretical studies confirm that the internal doped N can interact strongly with the surface-loaded CuSAs by modulating the d-p-band electronic coupling. The enhancement of d-p-band electronic coupling enhances the strong electron interaction between CuSA and support of N-doped TiO2. Especially, it significantly affects the d-p-band electronic structure of the catalyst surface lattice and causes electron redistribution in the local structure of surface CuSAs, which can optimize the surface hydrogen evolution kinetics and promote hydrogen production. Consequently, the photocatalytic hydrogen evolution activity, photoelectric response rate and light energy utilization of CuSAs-N/TiO2 are significantly improved. This work reveals the fundamental necessity of d-p-band electron coupling in MSI and catalyst surface electronic structure for driving solar water splitting. It provides valuable insights for the rational design of metal single-atom photocatalysts with high activity and efficient light energy utilization.

Visible-Near-Infrared Self-powered Photodetector Based on FePSe3

As a type of layered van der Waals material, transition metal phosphorus trichalcogenide FePSe3’s high carrier mobility and light absorption capability offering this p-type semiconductor promising utilization in broadband optoelectronics detection. Despite of the specific photoelectric response behavior of the FePSe3-based solid-state photodetectors, the self-powering potential of the FePSe3-based devices still remains unexplored. In this study, we harnessed the architecture of the photoelectrochemical photodetector and fabricated a FePSe3-based device to investigate its photoelectric performance under different illumination and bias conditions. It was found that the device demonstrated a visible-near-infrared self-powering detection capability ranging from 400 to 800 nm, fast response speed, high sensitivity and outstanding cyclic stability. This research signifies the promising potential of FePSe3 in the field of self-powered optoelectronics.

Organic Polymer-Based Photodiodes for Optoelectronic Reservoir Computing with Time-Based Coding.

The integration of optoelectronic devices with reservoir computing offers a novel and effective approach to in-sensor computing. This work presents a hybrid digital-physical solution that leverages the high-performance poly[(bithiophene)-alternate-(2,5-di(2-octyldodecyl)-3,6-di(thienyl)-pyrrolyl pyrrolidone)] (DPPT-TT) organic polymer-based photodiodes for the hardware implementation of reservoir computing system. The photodiodes demonstrate nonlinear photoelectric responses, fading memory, and cyclical stability, in relation to the temporal information on light stimuli. These attributes enable effective mapping, historical context sensitivity, and consistent performance, with time-encoded inputs, which are particularly essential for accurate and continuous processing of time series data. The optoelectronic reservoir computing system with pulse width modulation (PWM) coding demonstrates impressive performance in the prediction of chaotic sequences, achieving a normalized root-mean-square error as low as 0.095 with optimized parameters. The DPPT-TT-based photodiodes and time-based coding offer a hardware-efficient solution for reservoir computing, significantly advancing Internet of Things applications.

Enhanced charge separation at the interface of Cu2O/CuSCN composite thin films synthesized by electrodeposition technique

This study focuses on the synthesis and characterization of hole transport layers (HTLs) for solar cells, par- ticularly copper(I) thiocyanate (CuSCN) and cuprous oxide (Cu2O), synthesized via electrodeposition tech- niques. CuSCN and Cu2O offer promising properties for efficient charge transport in photovoltaic devices. The synthesis processes involve precise control of deposition parameters to achieve desired film morpholo- gies and properties. Characterization techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), and ultraviolet-visible (UV-Vis) spectroscopy provide insights into film morphology and optical properties. Optimization of synthesis parameters for Cu2O films is explored to enhance their electrical properties. Photoelectric response measurements indicate improved charge separation at the interface of Cu2O/CuSCN composite films. These findings can contribute to the advancement of solar cell technology. Furthermore, the study extends its exploration to the fabrication of Cu2O by electrodeposition at different pH levels. SEM and X-ray diffraction (XRD) analyses reveal the impact of deposition parameters on film mor- phology and crystal structure, providing valuable insights for tailored synthesis approaches. Overall, this comprehensive study not only advances the understanding of HTL materials synthesis and optimization but also provides valuable guidance for the development of high-efficiency and stable solar cell devices.

Flame aerosol deposition Y3Al5O12:Yb 3+ , Er 3+ nanoparticles on monolayer MoS2 for broadening near-infrared photoelectroresponse

Monolayer molybdenum disulfide (MoS2) is a two-dimensional material with a direct bandgap widely used in photoelectric detection. It exhibits excellent characteristics such as an ultra- high specific surface area, strong light interaction, and good carrier mobility. However, due to the bandgap limitation, monolayer MoS2 can only efficiently detect visible wavelengths less than 680 Combining lanthanide-doped upconversion nanoparticles with monolayer MoS2 to realize near- infrared (NIR) photodetection is a feasible strategy. Thus, Y3Al5O12:Yb 3+ , Er3+ up-conversion nanoparticles are deposited on the surface of a monolayer MoS2 by flame aerosol deposition (FAD), significantly extending their photoelectric response range to the near-infrared 980 nm. The Y3Al5O12:Yb 3+ , Er3+ nanoparticles synthesized by flame can achieve efficient up-conversion from near-infrared (~980 nm) to visible light (~450, ~550, ~650 nm). Therefore, the visible light can be subsequently absorbed by monolayer MoS2. The carefully designed Y3Al5O12:Yb 3+ , Er3+ /MoS2 photodetector shows strong responsivity and highly specific detectivity in the near-infrared spectrum. Under the bias voltage of 3 V and laser irradiation of 980 nm at 2.8 μW, the newly designed MoS2 device achieves a responsivity of 16.82 A/W and a specific detectivity of 1.47×10 12 Jones, as the traditional monolayer MoS2 usually responds to zero. This work can further expand the application of two-dimensional materials and their composites in near-infrared photoelectric detection

Tartrate‐Anchored Tetranuclear Titanium‐Oxo Clusters Functionalized by Chromophore Ligands Exhibiting Photoelectric Response and Photodegradation Performances of Methylene Blue

ABSTRACTIn recent years, researchers have devoted considerable effort to the study of high crystalline titanium‐oxo clusters (TOCs), because TOCs are considered to be the molecular analogs of TiO2 nanoparticles and have the potential to be utilized as effective cleaning and catalytic materials. Two new tartrate‐anchored tetranuclear TOCs functionalized with chromophore ligand of p‐nitrobenzoate (NB)/p‐toluenesulfonate (TS), namely, [Ti4(TA)(NB)2(OiPr)10] (1, H4TA = tartaric acid) and [Ti4(TA)(TS)2(OiPr)10] (2), were synthesized and their structures were characterized by various methods. The molecular structure analyses indicated that 1 and 2 are all tetranuclear {Ti4} TOCs, in which tartrate appears as a hexadentate μ4‐bridging ligand while p‐nitrobenzoate/p‐toluenesulfonate acts as a bidentate μ2‐bridging ligand. TOCs 1 and 2 are of good thermal and solvent stability. Furthermore, their photocurrent responses and photocatalytic degradation activities towards methylene blue (MB) were also investigated. In the presence of H2O2, the photocatalytic degradation efficiencies of MB by 1 and 2 are about 84.43% and 71.00%, respectively, at room temperature under visible light irradiation for 60 min. These findings shed light on designing efficient polycarboxylate‐based TOCs photocatalysts.

Switchable Photoelectric Response in High-Temperature Leadless Molecular Ferroelectric [C4N2H14][BiI5

Lead-free molecular ferroelectrics have garnered considerable attention for their promising potential, but such species with narrow band gap and sensitive photoelectric response are yet inadequate. Herein, we demonstrated the bulk ferroelectric photovoltaic effect in a novel lead-free molecular ferroelectric [C4N2H14][BiI5] with a Curie temperature (Tc) of 366 K and a narrow band gap (Eg) of 1.92 eV. The transformation of the crystal structure from the polar space group P21 to the nonpolar space group P21/m was elucidated using single-crystal X-ray diffraction. Room-temperature (RT) hysteresis loop reveals the intrinsic ferroelectricity of [C4N2H14][BiI5] with a relative small coercive field (Ec ∼ 0.27 kV/cm), saturation polarization (Ps ∼ 1.87 μC/cm2), and remanent polarization (Pr ∼ 1.61 μC/cm2). [C4N2H14][BiI5]-based solar device exhibits significant PV effects with a steady-state photocurrent (Jsc) of 3.54 μA/cm2 and a photovoltage (Voc) of 0.34 V under AM 1.5 G illumination, which can be significantly improved by adjusting the ferroelectric polarization, reaching a maximum Jsc of 140 μA/cm2 and Voc of 0.51 V. This work offers a promising avenue for lead-free molecular ferroelectric materials in the field of optoelectronic devices.

Photoelectron-transfer-effect grafting: Validation of a generalized strategy for fluorescence and photoelectrochemical dual-mode detection of hydrogen sulfide

BackgroundThe progress of modern research is constantly fueled by the convergence of multiple technologies. Despite the enormous potential of both fluorescence (FL) and photoelectrochemical (PEC) technologies, the development of synergistic PEC-FL sensing platforms that combine the advantages of both is still in its early stages due to their relatively recent inception. Hydrogen sulfide (H2S), possessing dual irritant and asphyxiating traits, poses challenges for environmental preservation and human health. The development of the PEC-FL detection methodology for H2S in complex environmental settings is imperative. ResultsCombining FL and PEC sensing techniques, this work presented a new concept of photoinduced electron-transfer (PET) effect grafting for dual-mode fluorescence and PEC analysis. Briefly, a well-designed fluorescent molecule (BTFM-DNP) featuring the PET effect was synthesized and implemented to modulate the photoelectric response of the indium tin oxide (ITO)/BiOI photocathode electrode. After reacting with H2S, the thiolysis of dinitrophenyl ether eliminated the intramolecular PET effect and recovered the significant fluorescence of the probe. Remarkably, the newly formed 2,4-dinitrobenzenethiol (DBT) with strong electron-withdrawing groups was then grafted to the ITO/BiOI photoelectrode and achieved the successful transfer of the PET process, resulting in a sharp decrease in photocurrent. The as-developed dual-mode protocol exhibited good performance in terms of ultra-sensitivity, high selectivity, fast response, and a wide detection range from 1 pM to 80 μM. SignificanceThe newly developed PEC-FL sensing platform can be applied to detect H2S levels in both the environment and food. This study demonstrates a promising synergy between fluorescent probes and PEC sensors, offering a novel perspective on the advancement of multi-mode analysis techniques. This approach has the potential to significantly enhance detection accuracy and reliability.

An Updated Review for Performance Enhancement of Solar Cells by Spectral Modification

Photovoltaic technology has become one of the major renewable ways to generate electric power. However, the mismatch between the incident solar spectrum and photo-electric response efficiency of solar cells severely constrains their performance. Hence, spectral modification technologies, e.g., up-conversion (UC), down-conversion (DC), and luminescent down-shifting (LDS) technologies have been applied widely in the photovoltaic field to reform the incident spectrum to match the best response band possible. In this paper, we review the latest developments of the three technologies above in terms of material selection, optical characteristics, and photovoltaic performance. It is found that the three most popular materials for conversion are NaYF4: Er3+, Yb3+, and Yb3+. The excitation bands for the three technologies are 800–1550 nm, 250–488 nm, and 250–488 nm, respectively, while the emission bands are 523–669 nm, 520–1031 nm, and 490–1010 nm, respectively. Furthermore, issues hindering the development of spectral modification technologies are pointed out, e.g., low absorption efficiency, poor quantum conversion efficiency, and hurdles in commercialization. Finally, suggestions and solutions to address the above-mentioned issues are provided.

A synergistic bioelectrochemical-photocatalytic system for efficient uranium removal and recovery

Bioelectrochemical system (BES) is a promising technology for uranium recovery, which also enables simultaneous electricity generation. However, the bioelectrochemical recovery of uranium is hindered by its slow process due to the low reduction potential provided by microorganisms. Herein, we developed an innovative bioelectrochemical-photocatalytic system (BEPS) that combines the advantages of BES and photocatalysis, achieving enhanced uranium removal and recovery. The photogenerated electrons in BEPS possess a more negative reduction potential and stronger reduction capability than microbial electrons in BES, significantly accelerating uranium reduction and deposition on the electrode surface. Moreover, the electrons from the bioanode combine with photogenerated holes through the external circuit, effectively inhibiting the recombination of charge carriers. The BEPS significantly enhances uranium removal efficiency, kinetic, and electricity generation through a synergistic coupling mechanism between the bioanode and photocathode. Notably, the UO2 deposited on the electrode surface exhibited a recovery efficiency of 98.21 ± 1.37%, and the regenerated electrode sustained its photoelectric response and uranium removal capabilities. Our findings highlight the potential of the BEPS as an effective technology for uranium recovery and electricity generation.

Enhancing Photoelectric Response of Self-powered UV and Visible Detectors Using CuO/ZnO NRs Heterojunctions.

Understanding the development and performance of UV photodetectors is crucial, given their extensive applications in both military and civilian sectors. The evolution of self-powered photodetectors, especially those based on heterojunction nanostructures, has demonstrated significant potential for enhancing both device efficiency and functionality. By exploring the effects of material composition and structural design, can optimize these devices for improved photoelectric response and energy efficiency. In this study, we prepared the CuO/ZnO NRs heterojunction photodetector on an ITO substrate to enhance photoelectric response of UV detectors. The fabrication process utilized the hydrothermal method and the spin coating technique. The effect of CuO concentration on the optical response of the photodetector under UV radiation at wavelengths of 405nm and 385nm was investigated. The samples were characterized using FESSEM, XRD, EDX, and UV-Vis spectra. The device is further distinguished by its standard I-V curves and photocurrent-time curves, which demonstrate the device's behavior under various light conditions. The prepared thin films are polycrystalline, with CuO layers displaying monoclinic phases and ZnO layers exhibiting a hexagonal wurtzite phase. All samples have the potential to exhibit photovoltaic properties and self-powered capabilities. Furthermore, the I-V curve confirms that the photocurrent mechanism of these junctions adheres to the recombination standard, in addition to demonstrating correction behavior. A sample with a CuO concentration of 0.1M shows the highest photosensitivity, reaching 340,700%, and a photocurrent gain (Iph/Idark) of 3,408 when exposed to light irradiation at 405nm. Additionally, it exhibits a rapid response time of 0.8s.

Wireless and Opto-Stimulated Flexible Implants: Artificial Retina Constructed by Ferroelectric BiFeO3-BaTiO3/P(VDF-TrFE) Composites.

The degeneration of retinal photoreceptors is one of the primary causes of blindness, and the implantation of retinal prostheses offers hope for vision restoration in individuals who are completely blind. Flexible bioelectronic devices present a promising avenue for the next generation of retinal prostheses owing to their soft mechanical properties and tissue friendliness. In this study, we developed flexible composite films of ferroelectric BiFeO3-BaTiO3 (BFO-BTO) particles synthesized by the hydrothermal method and ferroelectric poly(vinyldene difluoride-trifluoroethylene) (P(VDF-TrFE)) polymer and investigated their applications in artificial retinas. Owing to the coupling of the photothermal effect of BFO-BTO particles and the pyroelectric effect of the P(VDF-TrFE) polymer, the composite films demonstrate a strong photoelectric response (a maximum peak-to-peak photovoltage > 80 V under blue light of 100 mW/cm2) in a wide wavelength range of light (from visible to infrared) with the inherent flexibility and ease of preparation, making it an attractive candidate for artificial retinal applications. Experimental results showed that blind rats implanted with artificial retinas of the composites display light-responsive behavior, showcasing the effectiveness of vision restoration. This study demonstrates a novel approach for employing ferroelectric materials in vision restoration and offers insights into future artificial retina design.

Enhanced photoelectric properties of TiO2 nanorod arrays through modulation of precursor concentration

This study synthesized titanium dioxide (TiO2) nanorod arrays and investigated their morphology and defect to the photoelectric response by varying the titanium isopropoxide (TTIP) precursor concentration from 0 to 66 mM. The vertically aligned rutile TiO2 nanorods exhibited film thicknesses ranging from 1 to 4.5 μm when the TTIP concentration equaled or exceeded 33 mM. Their rod length and diameter displayed a linear increase with the TTIP concentration. TiO2 arrays synthesized with a TTIP concentration of 33 mM exhibited the highest photoelectric response, measuring 52 μA/cm2 under xenon-lamp irradiation at a bias voltage of 0.8 V (vs. the Ag/AgCl reference). Notably, photoactivity was observed in the visible-light region as well. Photoluminescence spectra indicated a substantial reduction in electron-hole recombination compared to TiO2 arrays prepared from higher TTIP concentrations. X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses confirmed the presence of oxygen vacancies. Time-resolved photoluminescence spectra corroborated an extended electron lifetime, suggesting that surface oxygen vacancies facilitated the separation of photoexcited charge carriers. The presence of oxygen vacancies, combined with the unique array morphology, resulted in enhanced photocurrent density.

A Photoelectrochemical Retinomorphic Synapse.

Reproducing human visual functions with artificial devices is a long-standing goal of the neuromorphic domain. However, emulating the chemical language communication of the visual system in fluids remains a grand challenge. Here, a "multi-color" hydrogel-based photoelectrochemical retinomorphic synapse is reported with unique chemical-ionic-electrical signaling in an aqueous electrolyte that enables, e.g., color perception and biomolecule-mediated synaptic plasticity. Based on the specific enzyme-catalyzed chromogenic reactions, three multifunctional colored hydrogels are developed, which can not only synergize with the Bi2S3 photogate to recognize the primary colors but also synergize with a given polymeric channel to promote the long-term memory of the system. A synaptic array is further constructed for sensing color images and biomolecule-coded information communication. Taking advantage of the versatile biochemistry, the biochemical-driven reversible photoelectric response of the cone cell is further mimicked. This work introduces rich chemical designs into retinomorphic devices, providing a perspective for replicating the human visual system in fluids.