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Two diphosphanes with variable-length ligands tested as nucleophiles to prepare isoporphyrin copolymers in the presence of ditolylporphyrin of zinc (ZnT2P) prevented the oxidation of the diphosphine ligand. This paper demonstrates the power of this approach and describes the photoelectrocatalytic properties. The obtained copolymers were characterized by UV–vis spectroscopy, X-ray photoelectron spectroscopy, atomic force micrograph (AFM), EQCM (Electrochemical Quartz Cristal Microbalance) and electrochemistry. Their impedance properties (EIS) were studied and their photovoltaic performances were also investigated by photocurrent transient measurements under visible light irradiation.

In this study, the photoelectric properties of a complete series of GaS1−xSex (0 ≤ x ≤ 1) layered crystals are investigated. The photoconductivity spectra indicate a decreasing bandgap of GaS1−xSex as the Se composition x increases. Time-resolved photocurrent measurements reveal a significant improvement in the response of GaS1−xSex to light with increasing x. Frequency-dependent photocurrent measurements demonstrate that both pure GaS crystals and GaS1−xSex ternary alloy crystals exhibit a rapid decrease in photocurrents with increasing illumination frequency. Crystals with lower x exhibit a faster decrease in photocurrent. However, pure GaSe crystal maintains its photocurrent significantly even at high frequencies. Measurements for laser-power-dependent photoresponsivity and bias-voltage-dependent photoresponsivity also indicate an increase in the photoresponsivity of GaS1−xSex as x increases. Overall, the photoresponsive performance of GaS1−xSex is enhanced with increasing x, and pure GaSe exhibits the best performance. This result contradicts the findings of previous reports. Additionally, the inverse trends between bandgap and photoresponsivity with increasing x suggest that GaS1−xSex-based photodetectors could potentially offer a high response and wavelength-selectivity for UV and visible light detection. Thus, this work provides novel insights into the photoelectric characteristics of GaS1−xSex layered crystals and highlights their potential for optoelectronic applications.

In recent years, clean energy technologies that meet ever-increasing energy demands without the risk of environmental contamination has been a major interest. One approach is the utilization of plant leaves, which release redox-active NADPH as a result of photosynthesis, to generate photocurrent. In this work, we show for the first time that photocurrent can be harvested directly from the fruit of a cherry tree when associated with a bio-electrochemical cell. Furthermore, we apply electrochemical and spectroscopic methods to show that NADH in the fruit plays a major role in electric current production.

Lanthanum manganite (LMO) thin films were deposited by co-sputtering La and Mn targets in an Ar and O2 gas mixture. The films were synthesized on silicon and fused silica substrates. The influences of thermal annealing on the structure, optical and electrical properties of LMO films were investigated. The results exhibited a correlation between these properties. In the amorphous state, an increase in annealing temperature improved the optical transmission and decreased the electrical capacitance. The beginning of crystallization at 600 °C was manifested by a strong increase in the capacitance and a decrease in the optical transmission. At higher annealing temperature, polycrystalline films were obtained with different optical and electrical characteristics. On the other hand, the annealed LMO films showed a photocurrent effect during exposure to a weak LED light.

The density of donor-like state distributions in solution-processed indium–zinc-oxide (IZO) thin-film transistors (TFTs) is thoroughly analyzed using photon energy irradiation. This study focuses on quantitatively calculating the distribution of density of states (DOS) in IZO semiconductors, with a specific emphasis on their variation with indium concentration. Two calculation methods, namely photoexcited charge collection spectroscopy (PECCS) and photocurrent-induced DOS spectroscopy (PIDS), are employed to estimate the density of the donor-like states. This dual approach not only ensures the accuracy of the findings but also provides a comprehensive perspective on the properties of semiconductors. The results reveal a consistent characteristic: the Recombination–Generation (R-G) center energy ET, a key aspect of the donor-like state, is acquired at approximately 3.26 eV, irrespective of the In concentration. This finding suggests that weak bonds and oxygen vacancies within the Zn-O bonding structure of IZO semiconductors act as the primary source of R-G centers, contributing to the donor-like state distribution. By highlighting this fundamental aspect of IZO semiconductors, this study enhances our understanding of their charge-transport mechanisms. Moreover, it offers valuable insight for addressing stability issues such as negative bias illumination stress, potentially leading to the improved performance and reliability of solution-processed IZO TFTs. The study contributes to the advancement of displays and technologies by presenting further innovations and applications for evaluating the fundamentals of semiconductors.

Here, we report on using chemical vapor deposition to generate three kinds of gallium sulfide nanosheets, with thicknesses of approximately 10, 40, and 170 nm. Next, we performed Raman imaging analysis on these nanosheets to evaluate their properties. The 10 nm GaS nanosheets exhibited a nearly equal distribution of Raman imaging intensity, whereas the 40 and 170 nm GaS nanosheets exhibited an inclination toward the edges with higher Raman intensity. When the polarization of the laser was changed, the intensity of Raman imaging of the 10 nm thick GaS nanosheets remained consistent when illuminated with a 532 nm laser. Notably, a greater Raman intensity was discernible at the edges of the 40 and 170 nm GaS nanosheets. Three distinct GaS nanosheet devices with different film thicknesses were fabricated, and their photocurrents were recorded. The devices were exposed to light of 455 nm wavelength. The GaS nanosheet devices with film thicknesses of 40 and 170 nm exhibited a positive photoresponse even though the photocurrents were fairly low. In contrast, the GaS nanosheet device with a film thickness of 10 nm had a considerable current without light, even though it had a weak reaction to light. This study reveals the different spatial patterns of Raman imaging with GaS thickness, the wavelength of excitation light, and polarization. Remarkably, the I-V diagram revealed a higher dark-field current of 800 nA in the device with a GaS nanosheet thickness of approximately 10 nm, when using a voltage of 1.5 V and a laser of 445 nm wavelength. These findings are comparable with those theretical pretictions in the existing literature. In conclusion, the observation above could serve as a catalyst for future exploration into photocatalysis, electrochemical hydrogen production through water splitting, energy storage, nonlinear optics, gas sensing, and ultraviolet selective photodetectors of GaS nanosheet-based photodetectors.

Exposing catalytically active metal sites in metal–organic frameworks (MOFs) while maintaining porosity is beneficial for increasing electron transport to achieve better electrochemical energy conversion performance. Herein, we propose an in situ method for MOF formation and loading onto TiO2 nanorods (NR) using a simple solution-processable method followed by annealing to obtain TiO2-Co3O4. The as-prepared TiO2-ZIF-67 based photoanodes were annealed at 350, 450, and 550 °C to study the effect of carbonization on photo-electrochemical water oxidation. The successful loading of ZIF-67 on TiO2 and the formation of TiO2-Co3O4 heterojunction were confirmed by XRD, XPS, FE-SEM, and HRTEM analyses. TiO2-Co3O4-450 (the sample annealed at 450 °C) showed an enhanced photocurrent of 2.4 mA/cm2, which was 2.6 times larger than that of pristine TiO2. The improved photocurrent might be ascribed to the prepared p–n heterostructures (Co3O4 and TiO2), which promote electron–hole separation and charge transfer within the system and improve the photoelectrochemical performance. Moreover, the preparation of Co3O4 from the MOF carbonization process improved the electrical conductivity and significantly increased the number of exposed active sites and enhanced the photoresponse performance. The as-prepared ZIF-67 derived TiO2-Co3O4 based photoanodes demonstrate high PEC water oxidation, and the controlled carbonization method paves the way toward the synthesis of low-cost and efficient electrocatalysts.

In this study, the enhanced photodegradation of a high-concentration phenol red (PR) using very fine TiO2 nanocrystals by adding a KBrO3 electron acceptor was reported for the first time. The structural study on TiO2 nanocrystals using HRTEM, XRD, Raman, and EDX was performed and it confirmed the anatase phase of TiO2 nanocrystals. UV–Vis absorbance of 20 mg.L−1 PR was measured and the photodegradation was extracted. The KBrO3 concentration effects exhibited an important enhancement in the degradation of PR dye. The efficiency of PR was increased during 110 min from 75% of pure TiO2 to 92% and 98% of TiO2 with 1 mg and 5 mg KBrO3, respectively. For different samples, a first-order kinetic of dye degradation is confirmed. The instantaneous amount of degraded dye increased from 150 to 180 and 197 mg/g TiO2 with 1 mg and 5 mg KBrO3, respectively. The mechanism of the photodegradation reaction confirms the effect of OH- radicals on increasing the photocatalytic activities. The addition of electron acceptors KBrO3 improved the photocatalysis rate, where it prevented e-h recombination through conduction band electron capture, which increases the concentration of hydroxyl radicals. The proposed mechanism and results were supported by photocurrent measurements and a Raman spectra analysis of the final photodegraded products. The photocurrent of TiO2 was observed at 1.2 µA, which was significantly improved up to 13.2, and 21.3 µA with the addition of 1 mg and 5 mg of KBrO3. The Raman spectra of the final products confirmed that SO42− and carbons are byproducts of PR degradation.

In this study, we report the influence of vanadium oxide (VO), as a photosensitive component, on the photoactivity of TiO2 nanotubes (TNTs). A series of TNTs of varying tube diameter were synthesized by the anodization of titanium foils at different voltages, while vanadium oxide was deposited on TNTs by wet chemical deposition. An improvement in the optical properties of nanotubes was observed after the deposition of vanadium oxide. An improvement in the optical properties (redshift in UV-Vis spectra) of TNTs and TNT/VO was noted. The photocatalytic activity was improved with increasing tube diameter, while it was weakened after the deposition of VO. Furthermore, photoactivity was investigated in photodiodes based on TNTs or TNT/VO and single crystals of CH3NH3PbI3. The photoelectric measurement revealed that different TNT diameters did not influence the I-V characteristic of the photodiodes, while the deposition of VO improved the photocurrent for smaller TNTs.

Porous crystalline Ni-doped TiO2 films were produced using DC plasma electrolytic oxidation in refrigerated H2SO4 aqueous solutions containing NiSO4. The crystalline phase structure consisted of a mixture of anatase and rutile, ranging from ~30 to ~80 wt % rutile. The oxide films obtained at low NiSO4 concentration showed the highest photocurrent values under monochromatic irradiation in the UV-vis range, outperforming pure TiO2. By increasing NiSO4 concentration above a threshold value, the photoelectrochemical activity of the films decreased below that of undoped TiO2. Similar results were obtained using cyclic voltammetry upon polychromatic UV-vis irradiation. Glow discharge optical emission spectrometry (GD-OES) analysis evidenced a sulfur signal peaking at the TiO2/Ti interface. XPS spectra revealed that oxidized Ni2+, S4+ and S6+ ions were included in the oxide films. In agreement with photocurrent measurements, photoluminescence (PL) spectra confirmed that less intense PL emission, i.e., a lower electron-hole recombination rate, was observed for Ni-doped samples, though overdoping was detrimental.

Based on the LiLaTiO3 compound, a ceramic membrane for a photoelectrochemical cell was created. The microstructure, phase composition, and conductivity of a semiconductor photoelectrode and a ceramic membrane were studied by using various experimental methods of analysis. A ceramic Li conducting membrane that consisted of Li0.56La0.33TiO3 was investigated in solutions with different pH values. The fundamental possibility of creating a photoelectrochemical cell while using this membrane was shown. It was found that the lithium-conductive membrane effectively works in the photoelectrochemical system for hydrogen evolution and showed a good separating ability. When using a ceramic membrane, the pH in the cathode and anode chambers of the cell was stable during 3 months of testing. The complex impedance method was used to study the conductive ceramic membrane in a cell with separated cathode and anode chambers at different pH values of the electrolyte. The ceramic membrane shows promise for use in photoelectrochemical systems, provided that its resistivity is reduced (due to an increase in area and a decrease in thickness).

Monoclinic scheelite bismuth vanadate (BVO) microballs were prepared by a facile hydrothermal method and subsequently modified with 2 wt% of noble metals (NM = Au, Ag, Cu, Pt and Pd) by a photodeposition route. All materials were characterized by diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The photocatalytic performance was investigated by degradation of tetracycline antibiotic under visible light irradiation. Moreover, photocurrent generation under UV/vis was also examined. It was found that BVO modification with all tested NMs resulted in a significant improvement in photocatalytic performance. The highest activity was obtained for Cu/BVO with mainly oxidized forms of copper. Based on scavenger tests (∙O2− and ∙OH as the main responsible species for TC degradation) and redox properties, it was proposed that the Z-scheme mechanism between copper oxides and BVO was responsible for enhanced photocatalytic activity. However, the co-participation of zero-valent forms of NMs should also be considered, either as electron scavengers, plasmonic sensitizers or conductors. Presented data reveal that porous microballs, highly attractive for practical applications due to micro-sized diameter and efficient light harvesting inside the structure, could be efficiently used for environmental and energy purposes under solar radiation.

In this study, the photoelectric properties of a complete series of GaS 1- x Se x (0 ≤ x ≤ 1) layered crystals are investigated. The photoconductivity spectra indicate a decreasing bandgap of GaS 1- x Se x as the Se composition x increases. Time-resolved photocurrent measurements reveal a significant improvement in the response of GaS 1- x Se x to light with increasing x . Frequency-dependent photocurrent measurements demonstrate that both pure GaS crystals and GaS 1- x Se x ternary alloy crystals exhibit a rapid decrease in photocurrents with increasing illumination frequency. Crystals with lower x exhibit a faster decrease in photocurrent. However, pure GaSe crystal maintains its photocurrent significantly even at high frequencies. Measurements for laser-power-dependent photoresponsivity and bias-voltage-dependent photoresponsivity also indicate an increase in the photoresponsivity of GaS 1- x Se x as x increases. Overall, the photoresponsive performance of GaS 1- x Se x is enhanced with increasing x , and pure GaSe exhibits the best performance. This result contradicts the findings of previous reports. Additionally, the inverse trends between bandgap and photoresponsivity with increasing x suggest that GaS 1- x Se x -based photodetectors could potentially offer a high response and wavelength-selectivity for UV and visible light detection. Thus, this work provides novel insights into the photoelectric characteristics of GaS 1- x Se x layered crystals and highlights their potential for optoelectronic applications.

Research interest is active in Eu2+/Dy3-doped SrAl2O4 phosphors, and the photocurrent characteristics of Eu2+-doped SrAl2O4 without Dy3+ was investigated extensively. However, it exhibits a low photocurrent of ~1 μA owing to high resistance. In this study, the changes in a photo-induced current with grain size were examined. The effect of the processing methods on the microstructure and photocurrent characteristics of Eu2+-doped SrAl2O4 phosphors was investigated. (Sr0.99Eu0.01)Al2O4 powders were synthesized using a conventional solid-state method and calcined at 1350 °C under a 3% H2/(Ar + H2) reducing gas atmosphere. Sample pellets were fabricated as conventional and hot-press-sintered bodies at 1400 °C. A thin film of the sample was deposited on an alumina substrate by radio-frequency magnetron sputtering. Scanning electron microscopy revealed that the hot-press-sintered body has larger grains than the conventionally sintered body. The photo-induced current of the hot-press-sintered body at 400 lx was ~100 and ~1000 times higher than those of the conventionally sintered body and thin film, respectively. Impedance analysis confirmed that this dramatic increase in the photo-induced current is closely related to the increase in the grain size and crystallinity of the sample. This study verifies the applicability of Eu2+-doped SrAl2O4 as both a phosphor and photosensor.

In this work, we report the effect of zinc (Zn) and nickel (Ni) co-doping of hydrothermally synthesized hematite nanorods prepared on fluorine-doped tin oxide (FTO) substrates for enhanced photoelectrochemical (PEC) water splitting. Seeded hematite nanorods (NRs) were facilely doped with a fixed concentration of 3 mM Zn and varied concentrations of 0, 3, 5, 7, and 9 mM Ni. The samples were observed to have a largely uniform morphology of vertically aligned NRs with slight inclinations. The samples showed high photon absorption within the visible spectrum due to their bandgaps, which ranged between 1.9–2.2 eV. The highest photocurrent density of 0.072 mA/cm2 at 1.5 V vs. a reversible hydrogen electrode (RHE) was realized for the 3 mM Zn/7 mM Ni NRs sample. This photocurrent was 279% higher compared to the value observed for pristine hematite NRs. The Mott–Schottky results reveal an increase in donor density values with increasing Ni dopant concentration. The 3 mM Zn/7 mM Ni NRs sample produced the highest donor concentration of 2.89 × 1019 (cm−3), which was 2.1 times higher than that of pristine hematite. This work demonstrates the role of Zn and Ni co-dopants in enhancing the photocatalytic water oxidation of hematite nanorods for the generation of hydrogen.

Silicon nanowires (NWs) are appealing building blocks for low-cost novel concept devices with improved performances. In this research paper, we realized a hybrid platform combining an array of vertically oriented Si NWs with different types of bucky gels, obtained from carbon nanotubes (CNT) dispersed into an ionic liquid (IL) matrix. Three types of CNT bucky gels were obtained from imidazolium-based ionic liquids (BMIM-I, BIMI-BF4, and BMIM-Tf2N) and semiconductive CNTs, whose structural and optical responses to the hybrid platforms were analyzed and compared. We investigated the electrical response of the IL-CNT/NW hybrid junctions in dark and under illumination for each platform and its correlation to the ionic liquid characteristics and charge mobility. The reported results confirm the attractiveness of such IL-CNT/NW hybrid platforms as novel light-responsive materials for photovoltaic applications. In particular, our best performing cell reported a short-circuit current density of 5.6 mA/cm2 and an open-circuit voltage of 0.53 V.

A light-addressable potentiometric sensor (LAPS) is a chemical sensor that is based on the field effect in an electrolyte–insulator–semiconductor structure. It requires modulated illumination for generating an AC photocurrent signal that responds to the activity of target ions on the sensor surface. Although high-power illumination generates a large signal, which is advantageous in terms of the signal-to-noise ratio, excess light power can also be harmful to the sample and the measurement. In this study, we tested different waveforms of modulated illuminations to find an efficient illumination for a LAPS that can enlarge the signal as much as possible for the same input light power. The results showed that a square wave with a low duty ratio was more efficient than a sine wave by a factor of about two.

A perovskite photo-sensor is promising for a lightweight, thin, flexible, easy-to-coat fabrication process, and a higher incident photon-to-current conversion efficiency. We have investigated perovskite photo-sensors with a solution-processed compact TiO2 under a low-temperature process and an ultra-thin polyethylenimine ethoxylated (PEIE) as an electron injection layer. The TiO2 film is grown from an aqueous solution of titanium tetrachloride (TiCl4) at 70 °C by a chemical bath deposition method. For an alternative process, the ultra-thin PEIE is spin coated on the TiO2 film. Then, the perovskite layer is deposited on the substrate by the one- or two-step methods in the glovebox. Next, a hole transport layer of 2,2,7,7-tetrakis(N,N-di-p-methoxyphenylamine)-9, 9-spiro-bifluorene (Spiro-OMeTAD) solution is spin coated. The fabricated device structure is a photodiode structure of FTO/TiO2/(without or with) PEIE/(one- or two-step) perovskite layer/Spiro-OMeTAD/Au. For the sensing characteristics, a ratio of photo-to-dark-current density was 2.88 × 104 for the device with PEIE layer. In addition, a power-law relationship is discussed.

Understanding the relationships between the local structures and physical properties of low-dimensional ferroelectrics is of both fundamental and practical importance. Here, pressure-induced enhancement in the photocurrent of SbSI is observed by using pressure to regulate the lone-pair electrons (LPEs). The reconfiguration of LPEs under pressure leads to the inversion symmetry broken in the crystal structure and an optimum bandgap according to the Shockley–Queisser limit. The increased polarization caused by the stereochemical expression of LPEs results in a significantly enhanced photocurrent at 14 GPa. Our research enriches the foundational understanding of structure–property relationships by regulating the stereochemical role of LPEs and offers a distinctive approach to the design of ferroelectric-photovoltaic materials.

Hot-electron photodetectors (HEPDs) are triggering a strong surge of interest in applications of image sensors and optics communication, since they can realize photoelectric responses when the incident photon energy is lower than the bandwidth of the semiconductor. In traditional HEPD systems, the metal layers are dressed with regular gratings, which can only excite plasmonic resonance over a narrow bandwidth, limiting the hot-electron photoelectric effect. To break this limitation, hybrid plasmonic nanostructures should be applied in HEPDs. Here, we propose a TiO2 based HEPD device incorporated with a hybrid plasmonic nanostructure, which consists of Au nanoparticles (Au NPs) and a conformal transparent Au film. With the assistance of the plasmonic resonances excited in this hybrid nanostructure, the spectrum of the photocurrent response is significantly broadened from the UV band to the visible and near-infrared (NIR) ranges. It is demonstrated that at the wavelengths of 660 nm and 850 nm, the photocurrent in the hybrid HEPD device is enhanced by 610% and 960%, respectively, compared with the counterparts without the addition of Au NPs. This work promotes the development of high performances HEPDs, offering an alternative strategy for realizing photodetection and image sensing in the NIR range.

The photoelectrochemical properties of three metallofullerene-[12]cycloparaphenylene ([12]CPP) supramolecular complexes of Sc3N@C78⊂[12]CPP, Sc3N@C80⊂[12]CPP, and Sc2C2@C82⊂[12]CPP were studied. It was revealed that the photocurrent responses of these supramolecular complexes show enhancement compared with those of pristine metallofullerenes, indicating the efficient photocurrent generation and promoted charge carrier transport caused by the supramolecular interaction. The results show that Sc2C2@C82 and Sc2C2@C82⊂[12]CPP have the strongest photocurrents. Then, by comparing the photocurrent intensities of the metallofullerene-biphenyl derivates mixture and the metallofullerene⊂[12]CPP complexes, it was demonstrated that the host–guest interaction is the key factor promoting photocurrent enhancement. At the same time, by observing the microscopic morphologies of pristine fullerenes and supramolecular complexes, it was found that the construction of supramolecules helps to improve the morphology of metallofullerenes on FTO glass. Additionally, their electrical conductivity in optoelectronic devices was tested, respectively, indicating that the construction of supramolecules facilitates the transport of charge carriers. This work discloses the potential application of metallofullerene supramolecular complexes as photodetector and photoelectronic materials.

Tin disulfide (SnS2) is a promising semiconductor for use in nanoelectronics and optoelectronics. Doping plays an essential role in SnS2 applications, because it can increase the functionality of SnS2 by tuning its original properties. In this study, the effect of zinc (Zn) doping on the photoelectric characteristics of SnS2 crystals was explored. The chemical vapor transport method was adopted to grow pristine and Zn-doped SnS2 crystals. Scanning electron microscopy images indicated that the grown SnS2 crystals were layered materials. The ratio of the normalized photocurrent of the Zn-doped specimen to that of the pristine specimen increased with an increasing illumination frequency, reaching approximately five at 104 Hz. Time-resolved photocurrent measurements revealed that the Zn-doped specimen had shorter rise and fall times and a higher current amplitude than the pristine specimen. The photoresponsivity of the specimens increased with an increasing bias voltage or decreasing laser power. The Zn-doped SnS2 crystals had 7.18 and 3.44 times higher photoresponsivity, respectively, than the pristine crystals at a bias voltage of 20 V and a laser power of 4 × 10−8 W. The experimental results of this study indicate that Zn doping markedly enhances the optical response of SnS2 layered crystals.

An electrode of a light-induced cell for water splitting based on a broadband Tamm plasmon polariton localized at the interface between a thin TiN layer and a chirped photonic crystal has been developed. To facilitate the injection of hot electrons from the metal layer by decreasing the Schottky barrier, a thin n-Si film is embedded between the metal layer and multilayer mirror. The chipping of a multilayer mirror provides a large band gap and, as a result, leads to an increase in the integral absorption from 52 to 60 percent in the wavelength range from 700 to 1400 nm. It was shown that the photoresponsivity of the device is 32.1 mA/W, and solar to hydrogen efficiency is 3.95%.

TiO2 develops a higher efficiency when doping Bi into it by increasing the visible light absorption and inhibiting the recombination of photogenerated charges. Herein, a highly efficient Bi doped TiO2 photoanode was fabricated via a one-step modified sol-gel method and a screen-printing technique for the anode of photocatalytic fuel cell (PFC). A maximum degradation rate of 91.2% of Rhodamine B (RhB) and of 89% after being repeated 5 times with only 2% lost reflected an enhanced PFC performance and demonstrated an excellent stability under visible-light irradiation. The excellent degradation performance was attributed to the enhanced visible-light response and decreased electron-hole recombination rate. Meanwhile, an excellent linear correlation was observed between the efficient photocurrent of PFC and the chemical oxygen demand of solution when RhB is sufficient.

In this study, zinc-doped (α-Fe2O3:Zn), silver-doped (α-Fe2O3:Ag) and zinc/silver co-doped hematite (α-Fe2O3:Zn/Ag) nanostructures were synthesized by spray pyrolysis. The synthesized nanostructures were used as photoanodes in the photoelectrochemical (PEC) cell for water-splitting. A significant improvement in photocurrent density of 0.470 mAcm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) was recorded for α-Fe2O3:Zn/Ag. The α-Fe2O3:Ag, α-Fe2O3:Zn and pristine hematite samples produced photocurrent densities of 0.270, 0.160, and 0.033 mAcm−2, respectively. Mott–Schottky analysis showed that α-Fe2O3:Zn/Ag had the highest free carrier density of 8.75 × 1020 cm−3, while pristine α-Fe2O3, α-Fe2O3:Zn, α-Fe2O3:Ag had carrier densities of 1.57 × 1019, 5.63 × 1020, and 6.91 × 1020 cm−3, respectively. Electrochemical impedance spectra revealed a low impedance for α-Fe2O3:Zn/Ag. X-ray diffraction confirmed the rhombohedral corundum structure of hematite. Scanning electron microscopy micrographs, on the other hand, showed uniformly distributed grains with an average size of

Bi2Se3 is a topological quantum material that is used in photodetectors, owing to its narrow bandgap, conductive surface, and insulating bulk. In this work, Ag@Bi2Se3 nanoplatelets were synthesized on Al2O3(100) substrates in a two-step process of thermal evaporation and magnetron sputtering. X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) revealed that all samples had the typical rhombohedral Bi2Se3. Field-emission scanning electron microscopy (FESEM)-energy dispersive x-ray spectroscopy (EDS), XPS, and HRTEM confirmed the presence of the precipitated Ag. The optical absorptance of Bi2Se3 nanoplatelets in UV-visible range decreased with the Ag contents. Results of photocurrent measurements under zero-bias conditions revealed that the deposited Ag affected photosensitivity. A total of 7.1 at.% Ag was associated with approximately 4.25 and 4.57 times higher photocurrents under UV and visible light, respectively, than 0 at.% Ag. The photocurrent in Bi2Se3 at 7.1 at.% Ag under visible light was 1.72-folds of that under UV light. This enhanced photocurrent is attributable to the narrow bandgap (~0.35 eV) of Bi2Se3 nanoplatelets, the Schottky field at the interface between Ag and Bi2Se3, the surface plasmon resonance that is caused by Ag, and the highly conductive surface that is formed from Ag and Bi2Se3. This work suggests that the appropriate Ag deposition enhances the photocurrent in, and increases the photosensitivity of, Bi2Se3 nanoplatelets under UV and visible light.

We performed the investigation of the polarization-sensitive photocurrent generated in silver-palladium metal-semiconductor nanocomposite films under irradiation with nanosecond laser pulses at the wavelength of 2600 nm. It is shown that in both the transverse and the longitudinal configuration, the surface photogalvanic (SPGE) and photon drag effects (PDE) contribute to the observed photocurrent. However, the temporal profile of the transverse photocurrent pulse is monopolar at any polarization and angle of incidence, while the temporal profile of the longitudinal photocurrent pulse depends on the polarization of the excitation beam. Specifically, the irradiation of the film with the s-polarized excitation beam produces a monopolar photoresponse, while at p-polarized excitation, the photoresponse is bipolar, having a short front and long tail. Obtained experimental results are in agreement with the developed phenomenological theory, which describes transverse and longitudinal photocurrents due to SPGE and PDE in terms of relevant second-order nonlinear susceptibilities and allows us to obtain their dependences on the angle of incidence and polarization of the excitation laser beam. The pronounced dependence of the photocurrent on the angle of incidence and polarization of the excitation beam opens avenues toward the development of polarization- and position-sensitive detectors for industrial and space applications.

In this paper, the sampling current characteristics of the external circuit and the internal mechanism of the current generation in APD irradiated by a millisecond pulse laser were studied. The photocurrent of APD irradiated by a millisecond pulse laser with different energy densities was obtained by the sampling resistance of the external circuit. The photocurrent can be divided into a photocurrent stage, conduction stage and recovery stage in the time domain. This is mainly due to the carrier flow in APD, which leads to the lowering of the barrier between the PN junction. The research results of this paper can be extended to the response of the detector to the high-power infrared pulse laser and provide a certain experimental basis for the design of a millisecond pulse infrared laser detection circuit.

Conductive polymers are widely used as active and auxiliary materials for organic photovoltaic cells due to their easily tunable properties, high electronic conductivity, and light absorption. Several conductive polymers show the cathodic photogalvanic effect in pristine state. Recently, photoelectrochemical oxygen reduction has been demonstrated for nickel complexes of Salen-type ligands. Herein, we report an unexpected inversion of the photogalvanic effect caused by doping of the NiSalen polymers with anionic porphyrins. The observed effect was studied by means of UV-Vis spectroscopy, cyclic voltammetry and chopped light chronoamperometry. While pristine NiSalens exhibit cathodic photopolarization, doping with porphyrins inverts the polarization. As a result, photoelectrochemical oxidation of the ascorbate proceeds smoothly on the NiSalen electrode doped with zinc porphyrins. The highest photocurrents were observed on NiSalen polymer with o-phenylene imine bridge, doped with anionic zinc porphyrin. Assuming this, porphyrin serves both as a catalytic center for the oxidation of ascorbate and an internal electron donor, facilitating the photoinduced charge transport and anodic depolarization.

Pristine, and In-, Sn-, and (In, Sn)-doped Bi2Se3 nanoplatelets synthesized on Al2O3(100) substrate by a vapor–solid mechanism in thermal CVD process via at 600 °C under 2 × 10−2 Torr. XRD and HRTEM reveal that In or Sn dopants had no effect on the crystal structure of the synthesized rhombohedral-Bi2Se3. FPA–FTIR reveals that the optical bandgap of doped Bi2Se3 was 26.3%, 34.1%, and 43.7% lower than pristine Bi2Se3. XRD, FESEM–EDS, Raman spectroscopy, and XPS confirm defects (In3+Bi3+), (In3+V0), (Sn4+Bi3+), (V0Bi3+), and (Sn2+Bi3+). Photocurrent that was generated in (In,Sn)-doped Bi2Se3 under UV(8 W) and red (5 W) light revealed stable photocurrents of 5.20 × 10−10 and 0.35 × 10−10 A and high Iphoto/Idark ratios of 30.7 and 52.2. The rise and fall times of the photocurrent under UV light were 4.1 × 10−2 and 6.6 × 10−2 s. Under UV light, (In,Sn)-dopedBi2Se3 had 15.3% longer photocurrent decay time and 22.6% shorter rise time than pristine Bi2Se3, indicating that (In,Sn)-doped Bi2Se3 exhibited good surface conduction and greater photosensitivity. These results suggest that In, Sn, or both dopants enhance photodetection of pristine Bi2Se3 under UV and red light. The findings also suggest that type of defect is a more important factor than optical bandgap in determining photo-detection sensitivity. (In,Sn)-doped Bi2Se3 has greater potential than undoped Bi2Se3 for use in UV and red-light photodetectors.

The density of donor-like state distributions in solution-processed indium-zinc-oxide (IZO) thin-film transistors (TFTs) is thoroughly analyzed using photon energy irradiation. This study focuses on quantitatively calculating the distribution of density of states (DOS) in IZO semiconductors, with a specific emphasis on their variation with indium concentration. Two calculation methods, namely photoexcited charge collection spectroscopy (PECCS) and photocurrent-induced DOS spectroscopy (PIDS), are employed to estimate the density of the donor-like states. This dual approach not only ensures the accuracy of the findings but also provides a comprehensive perspective on the properties of semiconductors. The results reveal a consistent characteristic: the Recombination-Generation (R-G) center energy E T , a key aspect of the donor-like state, is acquired at approximately 3.26 eV, irrespective of the In concentration. This finding suggests that weak bonds and oxygen vacancies within the Zn-O bonding structure of IZO semiconductors act as the primary source of R-G centers, contributing to the donor-like state distribution. By highlighting this fundamental aspect of IZO semiconductors, this study enhances our understanding of their charge-transport mechanisms. Moreover, it offers valuable insight for addressing stability issues such as negative bias illumination stress, potentially leading to the improved performance and reliability of solution-processed IZO TFTs. The study contributes to the advancement of displays and technologies by presenting further innovations and applications for evaluating the fundamentals of semiconductors.

The classic solar cell model assumes that the photo-generated current is a constant, independent of the cell’s output voltage. Experimental data of CdTe solar cells, however, show that the photocurrent collection efficiency decreases with the increase of the cell’s output voltage. In this work, we proposed a theoretical model for the CdTe thin-film cell, which assumes that the loss of photocurrent in the CdTe absorber is primarily due to the minority carrier recombination in the neutral region and at the back contact. By solving the neutral region’s diffusion equation, with proper boundary conditions, we have obtained the analytical expressions of the photocurrent collection efficiency and the cell’s J-V performance. Our theoretical results agree well with the experimental data. According to our theoretical model, the CdTe thin-film solar cell has an optimized p-doping level. A higher doping density may not be always good for a CdTe solar cell due to the reduced depletion width and decreased photocurrent at normal operation voltage, although the higher doping density can improve the open-circuit voltage by increasing built-in voltage.

Cellulose nanomaterials have been widely investigated in the last decade, unveiling attractive properties for emerging applications. The ability of sulfated cellulose nanocrystals (CNCs) to guide the supramolecular organization of amphiphilic fullerene derivatives at the air/water interface has been recently highlighted. Here, we further investigated the assembly of Langmuir hybrid films that are based on the electrostatic interaction between cationic fulleropyrrolidines deposited at the air/water interface and anionic CNCs dispersed in the subphase, assessing the influence of additional negatively charged species that are dissolved in the water phase. By means of isotherm acquisition and spectroscopic measurements, we demonstrated that a tetra-sulfonated porphyrin, which was introduced in the subphase as anionic competitor, strongly inhibited the binding of CNCs to the floating fullerene layer. Nevertheless, despite the strong inhibition by anionic molecules, the mutual interaction between fulleropyrrolidines at the interface and the CNCs led to the assembly of robust hybrid films, which could be efficiently transferred onto solid substrates. Interestingly, ITO-electrodes that were modified with five-layer hybrid films exhibited enhanced electrical capacitance and produced anodic photocurrents at 0.4 V vs Ag/AgCl, whose intensity (230 nA/cm2) proved to be four times higher than the one that was observed with the sole fullerene derivative (60 nA/cm2).

Eu3+ doped porous nanostructured SrTiO3 films and powder fabricated by sol-gel route without using any precursor template are characterized by different morphology and phase composition. The films and the power show red and yellow luminescence with the most intensive photoluminescence (PL) bands at 612 nm and 588 nm, respectively. Raman, secondary ion mass spectrometry (SIMS), and X-ray diffraction (XRD) analysis of undoped nanostructured porous SrTiO3 films showed the presence of TiO2, SrO, and SrTiO3 phases and their components. The undoped porous SrTiO3 films are photosensitive and demonstrate resistive switching. The capacitance-voltage hysteresis loops with the width of about 6 V in the frequency range of 2 kHz—2 MHz were observed.

A new type of near-infrared (NIR)-sensing organic phototransistor (OPTR) was designed and fabricated by employing a channel/dielectric/sensing (CDS) triple layer structure. The CDS structures were prepared by inserting poly(methyl methacrylate) (PMMA) dielectric layers (DLs) between poly(3-hexylthiophene) (P3HT) channel layers and poly[{2,5-bis-(2-octyldodecyl)-3,6-bis-(thien-2-yl)-pyrrolo[3,4-c]pyrrole-1,4-diyl}-co-{2,2′-(2,1,3-benzothiadiazole)-5,5′-diyl}] (PODTPPD-BT) top sensing layers. Two different thicknesses of PMMA DLs (20 nm and 50 nm) were applied to understand the effect of DL thickness on the sensing performance of devices. Results showed that the NIR-OPTRs with the CDS structures were operated in a typical n-channel mode with a hole mobility of ca. 0.7~3.2 × 10−4 cm2/Vs in the dark and delivered gradually increased photocurrents upon illumination with an NIR light (905 nm). As the NIR light intensity increased, the threshold voltage was noticeably shifted, and the resulting transfer curves showed a saturation tendency in terms of curve shape. The operation of the NIR-OPTRs with the CDS structures was explained by the sensing mechanism that the excitons generated in the PODTPPD-BT top sensing layers could induce charges (holes) in the P3HT channel layers via the PMMA DLs. The optically modulated and reflected NIR light could be successfully detected by the present NIR-OPTRs with the CDS structures.

Plasmonic nanostructures have played a key role in extending the activity of photocatalysts to the visible light spectrum, preventing the electron–hole combination and providing with hot electrons to the photocatalysts, a crucial step towards efficient broadband photocatalysis. One plasmonic photocatalyst, Au/TiO2, is of a particular interest because it combines chemical stability, suitable electronic structure, and photoactivity for a wide range of catalytic reactions such as water splitting. In this review, we describe key mechanisms involving plasmonics to enhance photocatalytic properties leading to efficient water splitting such as production and transport of hot electrons through advanced analytical techniques used to probe the photoactivity of plasmonics in engineered Au/TiO2 devices. This work also discusses the emerging strategies to better design plasmonic photocatalysts and understand the underlying mechanisms behind the enhanced photoactivity of plasmon-assisted catalysts.

Supercell atomic models of composite films on the basis of graphene and single-wall carbon nanotubes (SWCNTs) with an irregular arrangement of SWCNTs were built. It is revealed that composite films of this type have a semiconducting type of conductivity and are characterized by the presence of an energy gap of 0.43–0.73 eV. It was found that the absorption spectrum of composite films contained specific peaks in a wide range of visible and infrared (IR) wavelengths. On the basis of calculated composite films volt-ampere characteristics (VAC), the dependence of the current flowing through the films on the distance between the nanotubes was identified. For the investigated composites, spectral dependences of the photocurrent were calculated. It was shown that depending on the distance between nanotubes, the maximum photocurrent might shift from the IR to the optical range.

The Scher–Montroll model successfully describes subdiffusive photocurrents in homogeneously disordered semiconductors. The present paper generalizes this model to the case of fractal spatial disorder (self-similar random distribution of localized states) under the conditions of the time-of-flight experiment. Within the fractal model, we calculate charge carrier densities and transient current for different cases, solving the corresponding fractional-order equations of dispersive transport. Photocurrent response after injection of non-equilibrium carriers by the short laser pulse is expressed via fractional stable distributions. For the simplest case of one-sided instantaneous jumps (tunneling) between neighboring localized states, the dispersive transport equation contains fractional Riemann–Liouville derivatives on time and longitudinal coordinate. We discuss the role of back-scattering, spatial correlations induced by quenching of disorder, and spatiotemporal non-locality produced by the fractal trap distribution and the finite velocity of motion between localized states. We derive expressions for the photocurrent and transit time that allow us to determine the fractal dimension of the distribution of traps and the dispersion parameter from the time-of-flight measurements.

Light trapping in single nanowires (NWs) is of vital importance for photovoltaic applications. However, circular NWs (CNWs) can limit their light-trapping ability due to high geometrical symmetry. In this work, we present a detailed study of light trapping in single silicon NWs with an elliptical cross-section (ENWs). We demonstrate that the ENWs exhibit significantly enhanced light trapping compared with the CNWs, which can be ascribed to the symmetry-broken structure that can orthogonalize the direction of light illumination and the leaky mode resonances (LMRs). That is, the elliptical cross-section can simultaneously increase the light path length by increasing the vertical axis and reshape the LMR modes by decreasing the horizontal axis. We found that the light absorption can be engineered via tuning the horizontal and vertical axes, the photocurrent is significantly enhanced by 374.0% (150.3%, 74.1%) or 146.1% (61.0%, 35.3%) in comparison with that of the CNWs with the same diameter as the horizontal axis of 100 (200, 400) nm or the vertical axis of 1000 nm, respectively. This work advances our understanding of how to improve light trapping based on the symmetry breaking from the CNWs to ENWs and provides a rational way for designing high-efficiency single NW photovoltaic devices.

Single nanowires (NWs) are of great importance for optoelectronic applications, especially solar cells serving as powering nanoscale devices. However, weak off-resonant absorption can limit its light-harvesting capability. Here, we propose a single NW coated with the graded-index dual shells (DSNW). We demonstrate that, with appropriate thickness and refractive index of the inner shell, the DSNW exhibits significantly enhanced light trapping compared with the bare NW (BNW) and the NW only coated with the outer shell (OSNW) and the inner shell (ISNW), which can be attributed to the optimal off-resonant absorption mode profiles due to the improved coupling between the reemitted light of the transition modes of the leak mode resonances of the Si core and the nanofocusing light from the dual shells with the graded refractive index. We found that the light absorption can be engineered via tuning the thickness and the refractive index of the inner shell, the photocurrent density is significantly enhanced by 134% (56%, 12%) in comparison with that of the BNW (OSNW, ISNW). This work advances our understanding of how to improve off-resonant absorption by applying graded dual-shell design and provides a new choice for designing high-efficiency single NW photovoltaic devices.

This paper presents a succinct exploration of several analytical methods for extracting the parameters of the single-diode model (SDM) of a photovoltaic (PV) module under standard test conditions (STC). The paper investigates six methods and presents the detailed mathematical analysis leading to the development of each method. To evaluate the performance of these methods, MATLAB-based software has been devised and deployed to generate the results of each method when used to extract the SDM parameters of various PV test modules of different PV technologies. Similar software has also been developed to extract the same parameters using well-established numerical and iterative techniques. A comparison is subsequently made between the synthesized results and those obtained using numerical and iterative methods. The comparison indicates that although analytical methods may involve a significant amount of approximations, their accuracy can be comparable to that of their numerical and iterative counterparts, with the added advantage of a significant reduction in computational complexity, and without the initialization and convergence difficulties, which are normally associated with numerical methods.

This paper presents a concise discussion and an investigation of the most literature-reported methods for modifying the lumped-circuit parameters of the single-diode model (SDM) of a photovoltaic (PV) module, to suit the prevailing climatic conditions of irradiance and temperature. These parameters provide the designer of a PV system with an essential design and simulation tool to maximize the efficiency of the system. The parameter modification methods were tested using three commercially available PV modules of different PV technologies, namely monocrystalline, multicrystalline, and thin film types. The SDM parameters of the three test modules were extracted under standard test conditions (STC) using a well-established numerical technique. Using these STC parameters as reference values, the parameter adjustment methods were subsequently deployed to calculate the modified parameters of the SDM under various operating conditions of temperature and irradiance using MATLAB-based software. The accuracy and effectiveness of these methods were evaluated by a comparison between the calculated and measured values of the modified parameters.

Dye-sensitized photocatalytic hydrogen production using a boron-dipyrromethene (BODIPY) organic material having a pyridyl group at the anchor site was investigated. Phenyl, carbazole, and phenothiazine derivatives were introduced into BODIPY dyes, and their photocatalytic activities were examined. Identification was performed by nuclear magnetic resonance (NMR), infrared (IR), mass (MS) spectra, and absorption spectra, and catalyst evaluation was performed by using visible-light irradiation and photocatalytic hydrogen production and photocurrent. These dyes have strong absorption at 600–700 nm, suggesting that they are promising as photosensitizers. When the photocatalytic activity was examined, stable catalytic performance was demonstrated, and the activity of the Pt-TiO2 photocatalyst carrying a dye having a carbazole group was 249 μmol/gcat·h. Photocurrent measurements suggest that dye-sensitized photocatalytic activity is occurring. This result suggests that BODIPY organic materials with pyridyl groups as anchor sites are useful as novel dye-sensitized photocatalysts.

Carbon nanotubes (CNTs)-based sensors have gained significant importance due to their tremendous electrical and physical attributes. CNT-based gas sensors have high sensitivity, stability, and fast response time compared to that of solid-state sensors. On exposure to a large variety of organic and inorganic compounds, the conductivity of CNT changes. This change in electrical conductivity is being used as a detection signal to detect different target molecules. Hydrogen-sulfide and benzene are hazardous gases that can cause serious health issues in humans. Therefore, it is mandatory to detect their presence in industrial and household environments. In this article, we simulated CNT-based benzene and hydrogen-sulfide sensor with a nanoscale semiconductor device simulator—Quantumwise Atomistix Toolkit (ATK). The change in the device density of states, electric current, and photocurrent in the presence of target molecules have been calculated. The change in photocurrent in the presence of target molecules has been proposed as a novel detection mechanism to improve the sensor selectivity and accuracy. This change in photocurrent as well as electric current in the presence of target molecules can be used simultaneously as detection signals. Our intension in the future is to physically fabricate this simulated device and use photocurrent as well as electric current as detection mechanisms.

Photoconversion processes such as electron injection (photooxidation) and dye regeneration (reduction) in dye-sensitized solar cells (DSSCs) occur at considerably inhomogeneous semiconductor/dye/electrolyte interfaces, implying a very high heterogeneity of interfacial photoconversion kinetics. Herein, we present a temporally and spatially resolved investigation of DSSCs comprising a cover glass photoanode with a 100-nm thick TiO2 layer loaded with the metal-free organic dye sensitizer MK-2, which is performed by employing laser scanning microscopy (LSM) for the simultaneous measurement of the photocurrent (PC) and photoluminescence (PL) of DSSCs under short-circuit conditions. Analysis of PL decay curves and the excitation rate dependences of PC and PL obtained for local (or submicrometric) areas of the MK-2-DSSC allows disclosing and quantifying three types of dyes coexisting in the DSSCs: (i) a dye that only generates PC (“PC-dye,” 75% of total dye molecules in the DSSC), (ii) a dye that generates both PC and PL (“PCPL-dye,” 20%), and (iii) a dye that only generates PL (“PL-dye,” 5%). Considering recent theoretical reports on cyanoacrylic dyes, we propose that the PC-dye and the PCPL-dye are covalently bound on a TiO2 surface with different adsorption modes (presumably bidentate and tridentate bridging configurations), whereas the PL-dye is noncovalently trapped within a mesoporous TiO2 film.

Titanium oxide (TiO2) and iron oxide (α-Fe2O3) hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS) and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC) water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic films could be explained by ability to address some of the hematite drawbacks by the deposition of very thin films (25 nm) consisting of small densely packed particles and by doping with Sn.

Over the last decade graphene based electronic devices have attracted the interest of researchers due to their exceptional chemical, electrical and optical properties. Graphene is very sensitive to any physical changes in its surrounding environment and, inherently, has very low electronic noise. This property of graphene makes it a suitable candidate for sensor applications. The purpose of the work presented in this article is to demonstrate the ability of graphene derivatives to detect toxic organic compounds like phenol and methanol. A novel method for the detection of organic compounds (phenol and methanol) has been introduced in this article. In this method, a change in the photocurrent, as well as electric current, have been used as detection signals to improve the sensor accuracy and selectivity for specific target molecules. A nanoscale electronic device simulator, Quantumwise Atomistix Toolkit (ATK), has been used to simulate graphene nanosheet and armchair graphene nanoribbon based sensors. Devices density of states (DOS), current−voltage curves and photocurrent curves have been calculated with the ATK simulator. In the proximity of target molecules, a significant change in DOS, electric current and photocurrent have been observed. The simulated graphene based structures can be converted into physical sensors to obtain a low cost, small sized, integrated sensing device.

An erbium-doped silicon transistor prepared by ion implantation and co-doped with oxygen is investigated by photocurrent generation in the telecommunication range. The photocurrent is explored at room temperature as a function of the wavelength by using a supercontinuum laser source working in the μW range. The 1-μm2 transistor is tuned to involve in the transport only those electrons lying in the Er-O states. The spectrally resolved photocurrent is characterized by the typical absorption line of erbium and the linear dependence of the signal over the impinging power demonstrates that the Er-doped transistor is operating far from saturation. The relatively small number of estimated photoexcited atoms (≈ 4 × 10 4 ) makes Er-dpoed silicon potentially suitable for designing resonance-based frequency selective single photon detectors at 1550 nm.

The photoactive materials broadly applied in catalysis and energy conversion are generally composed of metal oxides. Among these oxides, ZnO showed a promising photocatalytic activity; however, traditional synthetic routes generated by-products and large amounts of secondary waste. Herein, we report the use of bipolar electrochemistry to generate ZnO nanoparticles using deionized water and a zinc metal to conform to green chemistry practices. TEM imaging demonstrated that the sizes of the bipolar-made ZnO particles were smaller than the commercial sample. The presence of structural defects in ZnO was correlated with the chemical shifts analyzed by X-ray photoelectron spectroscopy (XPS) and by different concentrations of O2− ions in stoichiometric and defected lattice. Further, the diffuse reflectance UV⁻Vis studies demonstrated a blue-shift in the reflectance spectrum for the bipolar-made oxide. This was also an indication of defects in the ZnO lattice, which related to the formation of shallow levels in the bandgap of the material. The structural and morphological differences influenced the photocatalytic characteristics, revealing a higher photocurrent for the bipolar-made ZnO when compared to the reference sample. This was further manifested in lower total resistivity for all anodes made from the non-stoichiometric ZnO, and also in their shorter diffusion length for charge exchange and electron lifetimes.

Conjugated polymers with stabilizing coordination units for single-site catalytic centers are excellent candidates to minimize the use of expensive noble metal electrode materials. In this study, conjugated metallopolymer, POS[Cu], was synthesized and fully characterized by means of spectroscopical, electrochemical, and photophysical methods. The copper metallopolymer was found to be highly active for the electrocatalytic hydrogen generation (HER) in an aqueous solution at pH 7.4 and overpotentials at 300 mV vs. reversible hydrogen electrode (RHE). Compared to the platinum electrode, the obtained overpotential is only 100 mV higher. The photoelectrochemical tests revealed that the complexation of the conjugated polymer POS turned its intrinsically electron-accepting (p-type) properties into an electron-donor (n-type) with photocurrent responses ten times higher than the organic photoelectrode.