Incident Photon-to-electron Conversion Efficiency Research Articles

Enhancing dye-sensitized solar cell performance: Optimizing Cu2ZnSnS4/ZnCo2O4 nanocomposites as efficient and cost-effective counter electrodes

This study investigates the utilization of Cu2ZnSnS4/ZnCo2O4 (CZTS/ZCO) nanocomposites prepared through hydrothermal and combustion methods as counter electrodes in Dye-Sensitized Solar Cells (DSSCs). Different ratios of Cu2ZnSnS4 and ZnCo2O4 were explored, and comprehensive analyses were conducted using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), High-Resolution TEM (HRTEM), Brunauer–Emmett–Teller (BET) surface area analysis, Raman Spectroscopy, Electrochemical Impedance Spectroscopy (EIS), cyclic voltammetry (CV), Tafel analysis, Field Emission Scanning Electron Microscopy (FESEM), and Incident Photon-to-Electron Conversion Efficiency (IPCE), alongside long-term stability assessments. The CZTS:ZCO ratio of 2:1 exhibited the highest efficiency, reaching 8.81 %, with an open-circuit voltage of 729 mV, short-circuit current of 17.80 mAcm−2, and a fill factor of 67.9 %. This surpasses the efficiency of the reference Pt cell (8.42 %), which had an open-circuit voltage of 735 mV, short-circuit current of 17.16 mAcm−2, and a fill factor of 66.8 %. The average crystallite sizes for the main peaks of CZTS and ZCO samples were estimated to be 19.8 and 16.7 nm, respectively. The crystallite size can significantly affect the charge transfer and conductivity in the counter electrode during electrochemical processes; the presence of nanocrystals with these sizes can notably enhance the electrochemical properties and conductivity of the synthesized samples. Raman analysis results indicate that no additional phases or secondary phases such as ZnS and CuSnS3 have formed in the kesterite CZTS structure, and the crystal has formed as a single phase. Additionally, the F2g modes in the Raman spectrum of ZCO indicate tetrahedral units in the spinel ZCO structure, and the A1g modes represent octahedral structures in this phase, indicating the formation of suitable ZCO phase. The superior performance of the CZTS/ZCO nanocomposite can be attributed to its enhanced crystalline structure, superior charge transport characteristics, and improved electrocatalytic behaviours.

InGaN based Schottky barrier solar cell: Study of the temperature dependence of electrical characteristics

The indium gallium nitride (InGaN) semiconductor alloy shows great promise for high-efficiency thin-film solar cells due to its intrinsic characteristics. However, there are major challenges in the development of high-quality p-doped and indium-rich InGaN layers to fabricate a pn or pin solar cell. This study focuses on the development of an alternative structure, not requiring p-doping, with a Schottky contact on n-type InGaN. The InGaN absorber was grown by metalorganic chemical vapor deposition and its structural, morphological and optical properties studied. Structural analysis by X-ray diffraction showed the growth of single crystal layers without phase separation. Indium compositions which vary up to around 8.3 % were confirmed by transmission measurements. The formation of V-shaped pits was observed with increased indium composition at lower growth temperatures. Schottky diodes based on InGaN with platinum metallic contacts were fabricated and their current–voltage characteristics studied in detail as a function of temperature. This analysis of the conduction mechanisms in Schottky/InGaN devices permitted in particular the extraction of the diode parameters as a function of the temperature showing a high rectification with an ideality factor of 1.15 with reverse saturation current of 6.7×10−9A at room temperature for an indium composition of 5.52 %. In addition, the analysis revealed the presence of a dual Gaussian distribution of barrier heights in a specific temperature range. Finally, the incident photon-to-electron conversion efficiency (IPCE) of the fabricated InGaN Schottky solar cells, measured using intensity-modulated photocurrent spectroscopy, reached a peak value of 51 %, which is among the highest published values for InGaN based solar cells.

Encapsulation of few-layered MoS2 on electrochemical-treated BiVO4 nanoarray photoanode: Simultaneously improved charge separation and hole extraction towards efficient photoelectrochemical water splitting

Bismuth vanadate (BiVO4) photoanode shows great potential for photoelectrochemical (PEC) water splitting but still suffers from the sluggish surface reaction kinetic and high charge loss. Further strengthening the intrinsic charge transport for the improvement of solar-to-hydrogen conversion becomes the top priority. Herein, an innovative highly-oriented E-BiVO4/MoS2 heterojunction photoanode is rationally designed and fabricated via directly encapsulating few-layered MoS2 nanosheets on electrochemical-treated BiVO4 (E-BiVO4) nanopyramid arrays. Systematic studies reveal that the electrochemical reduction process can create oxygen vacancies on BiVO4 lattice, thereby increasing the overall carrier concentration, and boosting the bulk and surface charge separation efficiencies. Meanwhile, the introduction of MoS2 as a heterojunction helps build the unidirectional charge transfer channels for further facilitated surface hole extraction and oxidation kinetics, synergistically devoting to the significantly enhanced PEC activity and photostability. As a result, the optimized E-BiVO4/MoS2 photoanode exhibits the highest photocurrent density of 2.11 mA/cm2 at 1.23VRHE and incident photon-to-electron conversion efficiency (IPCE) of 40.6 %, which are approximately 4.6 and 4.9 times higher than the pristine BiVO4. The present work demonstrates a feasible collaborative strategy to develop photoanodes with simultaneously improved charge separation and hole transport for efficient PEC water splitting application.

Using Various Solvents for Extracting Grape Juice as Dye and Applying It in Fabrications of Dye-Sensitized Solar Cells

Using grape juice as a natural dye source and employing a solvent extraction to isolate anthocyanins and subsequently harnessing them as sensitizers, dye-sensitized solar cells (DSSCs) were fabricated in this study. The extraction process required diverse solvents, including tert-butanol, acetonitrile, acetone, and ethanol, with multiple adjustments and parameter optimizations to determine the most effective ratio in extraction. In the preparation of the photoanode, commercial titanium dioxide powder, which combined 20 mol% anatase phase and 80 mol% rutile phase, was utilized and applied through a doctor blade technique. The prepared photoanodes were immersed in the extracted anthocyanin dye and subjected to being exposed at various times to ensure complete light exclusion throughout the process. For electrode preparation, a platinum film approximately 1 nm thick was sputter-coated onto an indium tin oxide (ITO) glass substrate. The photoanodes treated in a dye-soaking process were then sealed with the electrodes. We measured incident photon-to-electron conversion efficiency (IPCE) with ultraviolet-visible spectroscopy (UV-VIS) and a solar simulator to comprehensively assess the performance of the manufactured dye-sensitized solar cells.

Studies on the performance and stability of dye-sensitized solar cells based on the co-sensitization of N719 and RK1 dye-sensitizers

The intention of this research is to demonstrate how the co-sensitization of organic and inorganic dyes influences the overall performance of the proposed method for DSSCs at low light intensities and enhances the power conversion efficiency of dye-sensitized solar cells (DSSCs). A maximum efficiency of 6.21% at 108 W/m2 was achieved by the co-sensitization method-fabricated DSSC. The co-sensitized photovoltaic cells work together synergistically to minimize the rate of electron and hole recombination, which leads to an increase in efficiency. The ruthenium-based N719 dye and the organic sensitizer RK1 are used in this co-sensitization approach because both dye-sensitizers have a significant impact on the performance of the DSSC. The proposed solar cells were analyzed using their current-voltage (I-V), incident photon-to-electron conversion efficiency (IPCE), and various DSSC parameters vs time properties. The proposed device has also retained 93.29% of its initial performance even after 1000 h.

Bi nanoparticles modified the WO3/ZnWO4 heterojunction for photoelectrochemical water splitting

The novel ternary photoanode was successfully prepared by Bi nanoparticles (Bi NPs) modified on type II heterojunction of WO3-ZnWO4 using the simple and effective drop casting and chemical impregnation methods. The photoelectrochemical (PEC) experimental tests revealed that the photocurrent density of the ternary photoanode of WO3/ZnWO4(2)/Bi NPs reaches 3.0 mA/cm2 at 1.23 V (vs. RHE), which is 6 times of the WO3 photoanode. The incident photon-to-electron conversion efficiency (IPCE) at 380 nm wave length reaches 68%, which increases 2.8 times compared to WO3 photoanode. The observed enhancement can be attributed to the formation of type II heterojunction and modification of Bi NPs. The former broadens the absorption range for visible light and improves the carrier separation efficiency, while the latter enhances the light capture ability through the local surface plasmon resonance (LSPR) effect of Bi NPs and the generation of hot electrons.

Direct Growth of Polymeric Carbon Nitride Nanosheet Photoanode for Greatly Efficient Photoelectrochemical Water-Splitting.

A general method for the direct synthesis of highly homogeneous and dense polymerized carbon nitride (PCN) nanosheet films on F: SnO2 (FTO) is developed. Detailed photoelectrochemical (PEC) water-splitting studies reveal that the as-synthesized PCN films exhibit outstanding performance as photoanode for PEC water-splitting. The optimal PCN photoanode exhibits excellent photocurrent density of 650µA cm-2 , and monochromatic incident photon-to-electron conversion efficiency (IPCE) value up to 30.55% (λ= 400nm) and 25.97% (λ= 420nm) at 1.23 VRHE in 0.1m KOH electrolyte. More importantly, the PCN photoanode has an excellent hole extraction efficiency of up to 70 ± 3% due to the abundance of active sites provided by the PCN photoanode nanosheet, which promotes the transport rates of OER-relevant species. These PCN films provide a new benchmark for PCN photoanode materials.

Photovoltaic Performance of Perovskite Solar Cells and Their Continuous Charge Path Control in Electric Vehicles

Perovskite Solar Cells (PSCs) are new thin-film photovoltaic devices that have developed rapidly in recent years. It is considered a promising third-generation solar cell due to its high Monochromatic Incident Photon-to-electron Conversion Efficiency (IPCE), simple preparation process, and low cost. Firstly, the photoelectric characteristics of PSCs with four different structures and light-absorbing materials are analyzed. The results show that when CH3NH3PbI3 is used as the absorbing layer, the perovskite film with a porous structure has good crystallinity, and the photogenerated electron injection of TiO2 is more effective. The photoelectric Conversion Rate (CVR) of Pb-based organic cells with porous structure reaches 14.67%, and the photoelectric CVR of Pb-based organic cells with flat plate structure is only 6.35%. Then, a simple superimposed electrode type PSC is designed. Experiments have shown that the structure can greatly improve IPCE. The Spiro-MeOTAD layer should be retained. When the Layer one spraying amount is 250 μL, and the Layer two spraying amount is 500 μL, the IPCE obtained by the battery is the highest. The IPCE of the battery prepared by the ball milling method is higher than that of the battery prepared by the ultrasonic crushing method. Different substrate materials are compared. Using aluminum foil as the substrate can achieve the best photoelectric performance, and the corresponding photoelectric CVR reaches 11.62%. Based on the above test results, superimposed electrode-type PSCs are prepared and used in electric vehicle power generation devices. Super-Capacitor (SC) connection enables continuous charging in low-light conditions. The results show that the SC charges the designed superimposed electrode-type PSCs when the brightness decreases. The timing of charging and discharging is adjusted under the upper and lower limits of the threshold to ensure that the design PSCs remain charged.

Hybrid photonic-plasmonic photoelectrode for enhanced photoelectrochemical current generation

Photoelectrochemical (PEC) reactions realized through the nonradiative decay of plasmonic process in metallic nanostructure earned tremendous potential to harvest solar irradiance. In conventional metal-semiconductor photoelectrodes, the electric field confinement using optical resonating modes is crucial to instigate plasmonic charge for enhanced photocurrent generation. However, the effect of such resonant states in a semiconductor-free plasmonic photoelectrode is limitedly explored. In this essence, we have experimentally realized a Schottky junction-free plasmonic-photonic hybrid photoelectrode consisting of one-dimensional porous grating of gold nanoparticles (GNPs) on top of a ITO waveguide. This designed photoelectrode exhibits PEC photocurrent generation solely from plasmonic hole transfer to the molecules/ions at the metal-adsorbed water interface. Spectral overlapping of plasmonic activities with photonic modes and porosity-induced large metal-electrolyte interface surface area further enhance the charge generation and transfer. In the results, the GNPs photoelectrode recorded 3.4 and 12.6-fold increases in the incident photon to electron conversion efficiency (IPCE) in contrast to conventional gold bar grating photonic crystal and random GNPs photoelectrodes, respectively. Further, modal coupling of resonant states witnesses a substantial rise in the photocurrent generation than the uncoupled resonant states. The present report delivers a facile strategy for tailoring the plasmonic photocurrent generation in futuristic solar energy harvesting applications.

Low-temperature in situ deposited CuI-based hole-transporter for perovskite solar cells efficiency enhancement

CuI hole transporter-based perovskite solar cells (PSCs) are prepared via a low-temperature in situ deposition method. As demonstrated, the results of x-ray diffraction indicate that the CuI hole-transporter has been fabricated successfully and obtained a better stability, and this can be supported by corresponding scanning electron microscopy, including the dense surface and clear cross section. Furthermore, a maximum incident photon-to-electron conversion efficiency (IPCE) of ∼16.78% is obtained at the CuI-based PSC cell with 2nd time deposition, which can be mainly attributed to the fact that, with the fewer defects in the high-quality interface and matched potential structure for promoting carrier interface immigration/diffusion, the CuI-based hole-transporter exhibits decent hole-extraction to make photo-generated electron/holes have a matched mobility. The remaining PbI2, with a better passivation, can inhibit carrier recombination, and both can improve the IPCE efficiently. Therefore, this lower cost and easily controlled technique is suitable for large-scale solar cells.

Enhancement of photoelectrochemical performance of BiFeO3 by Sm3+ doping

Bismuth ferrite (BiFeO3) holds great potentials in the photoelectrocatalysis due to the advantages of low cost, narrow band gap and good chemical stability. However, the photoelectrochemical performance of BiFeO3 is usually inhibited by the poor charge carrier transport. Here, we report the flame annealing synthesized Sm3+ doped BiFeO3 photocathodes for efficient hydrogen production. Greatly enhanced water reduction activity was found in doped samples. The Bi0.95Sm0.05FeO3 composition exhibited largest photocurrent density of 0.1061 mA cm−2 at 0 V vs. RHE in 0.5 M Na2SO4, which was 5.6 times higher than that of the pristine BiFeO3. Mott-Schottky analysis and electrochemical impedance spectra proved that the Bi3+substitution increased the charge carrier concentration and facilitated the charge migration. Incident photon-to-electron conversion efficiency (IPCE) value for Bi0.95Sm0.05FeO3 film (∼6.39% at 325 nm) was approximately ten times higher than that of undoped sample. The high performance can be ascribed to the rational Sm3+ doping, which can improve visible light absorption ability, facilitate the charge carrier transport kinetics and hinder the recombination of photogenerated carriers. Our work provides a facile cation doping with rare earth ions to improve the photoelectrochemical performances.

Effect of the thickness on the photocatalytic and the photocurrent properties of ZnO films deposited by spray pyrolysis

In this work, we have investigated the structure, morphology, photoluminescence, photocatalytic and photocurrent properties of ZnO thin films as a function of their film thickness (tZnO) fabricated via ultrasonic spray pyrolysis technique. The X-Ray diffraction patterns exhibited the formation of polycrystalline wurtzite phase of ZnO. Scanning electron microscopy images showed the uniform morphology with nanorod structure. The photosensitivity and photocatalytic efficiency are found to be optimum at tZnO = 1200 nm and are attributed to the improved photogeneration of charge carriers and higher concentration of oxygen vacancies. A direct correlation is established between the photosensitivity and photodegradation process. The incident photon-to-electron conversion efficiency (IPCE) and photocatalytic efficiency for the ZnO film at tZnO = 1200 nm are estimated to be 31.5% and 100% respectively. The obtained result suggests that ZnO thin films are potential candidates for applications in various optoelectronic devices.

Investigation of decoupling of thermal and electrical performance of semi-transparent photovoltaic windows based on the external quantum efficiency

Semi-transparent photovoltaic (STPV) windows have great potential in buildings energy saving due to their power generation and reduction of buildings energy consumption. STPV windows have a complex optical-thermal-electrical coupling mechanism. However, previous studies have rarely considered the coupling mechanism when simulating the thermal and electrical performance of STPV windows, which has resulted in the power generation being incorrectly treated as waste heat. As has been mentioned in EN 50583:2016 and IEC 63092:2020, the calculation of thermal performance of STPV windows should consider the mechanism that part of absorbed solar energy is transformed into electricity rather than heat. With considering the mechanism, based on the external quantum efficiency (EQE) of solar cells, a decoupled optical, thermal, and electrical performance simulation method for STPV windows was proposed in this study. Firstly, the optical characteristics of STPV windows and the EQE of the integrated solar cells were measured by a spectrophotometer and a monochromatic incident photon-to-electron conversion efficiency (IPCE) testing device, respectively. The EQE was used to calculate the spectral photoelectric conversion efficiency (SPCE) of STPV windows. Then, the SPCE was subtracted from the original absorptance and added to the front reflectance at corresponding wavelength, thereby decoupling the thermal and electrical performance. To verify the importance of the decoupling, the thermal and electrical performance of STPV windows with and without decoupling were investigated using EnergyPlus and WINDOW programs. An outdoor experimental rig was used to validate the simulation results of EnergyPlus, it was found that the decoupled results match well with experimental results. The simulation results show that in the coupled case, the window temperature and cooling load were overestimated, while the heating load was underestimated. However, the impact on power generation was negligible due to the low temperature coefficient of efficiency. Besides, for the analyzed STPV glazing configuration, the solar heat gain coefficient (SHGC) of the coupled case is relatively 9.3% higher than that of the decoupled case, when the solar cell coverage ratio is 70%. Moreover, the decoupled calculation method provides a theoretical basis for more accurate simulation and overall performance evaluation of STPV windows in maximum power point (MPP) state.

Highly crystalline hexagonalPbI2sheets on polyaniline/antimony tin oxide surface as a novel and highly efficient photodetector inUV, Vis, and nearIRregions

AbstractThe work reports on the preparation of polyaniline/lead iodide optoelectronic photodetector on antimony tin oxide (ATO) glass (PANI/PbI2/ATO) for providing a low‐cost light sensor in the UV, Vis, and near IR regions (wide optical range photodetector). The deposition of PbI2nanoparticles was carried out on the surface of PANI using the ionic adsorption deposition method. Four ATO/PANI/PbI2composites (I, II, III, and IV) were produced by varying the Pb2+concentrations (0.01, 0.03, 0.05, and 0.07 M, respectively). The chemical structure, morphology, optical, and electrical properties were assessed using different analytical tools. Scanning electron microscopy (SEM) imaging revealed the formation of a nanoporous PANI network. After PbI2incorporation within the PANI network, white nanoparticles formed on the surface. The average size of the PbI2nanoparticles was 220, 270, 280, and 320 nm for Pb2+concentration of 0.01, 0.03, 0.05, and 0.07 M, respectively. Moreover, x‐ray diffraction analysis confirmed PANI/PbI2composite formation, as witnessed by the appearance of new peaks at 12.77°, 34.31°, and 38.8 ° characteristic of PbI2. Through the optical analyses, the band gap values of the PANI/PbI2composites I, II, III, and IV were 2.63, 2.51, 2.46, and 2.48 eV, respectively. ATO/composite III was applied as an optoelectronic device for detection the light under different intensities or wavelengths, in which the current density (Jph) increase from 2.5 to 3.42 mA cm−2upon increasing of the light intensity from 25 to 100 mW.cm−2, respectively. Moreover, theJphrecorded an optimum value of 3.33 mA cm−2at 390 nm, which decreased to 2.09 mA cm−2at 490 nm and increased again to 3.13 mA cm−2at 636 nm. The optoelectronic photodetector exhibited an optimum incident photon to electron conversion efficiency (IPCE) of 10.7% at 390 nm. The photoresponsivity (R) and detectivity (D) were determined to be 107 mA cm−2and 3.38 × 1010Jones, respectively. Finally, a simple mechanism was proposed to account for the response of the prepared optoelectronic devices to the photon flux. Soon, our team will work on design an optoelectronic device that can be applied in the industrial field through the high technology device such as cameras and aircrafts for light detection.

Quasi-Solid-State SiO2 Electrolyte Prepared from Raw Fly Ash for Enhanced Solar Energy Conversion.

Quasi-solid-state electrolytes in dye-sensitized solar cells (DSSCs) prevent solvent leakage or evaporation and stability issues that conventional electrolytes cannot; however, there are no known reports that use such an electrolyte based on fly ash SiO2 (FA_SiO2) from raw fly ash (RFA) for solar energy conversion applications. Hence, in this study, quasi-solid-state electrolytes based on FA_SiO2 are prepared from RFA and poly(ethylene glycol) (PEG) for solar energy conversion. The structural, morphological, chemical, and electrochemical properties of the DSSCs using this electrolyte are characterized by X-ray diffraction (XRD), high-resolution field-emission scanning electron microscopy (HR-FESEM), X-ray fluorescence (XRF), diffuse reflectance spectroscopy, electrochemical impedance spectroscopy (EIS), and incident photon-to-electron conversion efficiency (IPCE) measurements. The DSSCs based on the quasi-solid-state electrolyte (SiO2) show a cell efficiency of 5.5%, which is higher than those of nanogel electrolytes (5.0%). The enhancement of the cell efficiency is primarily due to the increase in the open circuit voltage and fill factor caused by the reduced electron recombination and improved electron transfer properties. The findings confirm that the RFA-based quasi-solid-state (SiO2) electrolyte is an alternative to conventional liquid-state electrolytes, making this approach among the most promising strategies for use in low-cost solar energy conversion devices.

Plasmonic gold nanoparticle incorporated MgO-coated SnO2 photoanode for efficiency enhancement in dye-sensitized solar cells

SnO2 is an attractive semiconducting material suitable for application as the photoanode in dye sensitized solar cells (DSSCs) due to its wide energy band gap and notable photo stability. However, improved solar cell performance can be achieved only by using composites of SnO2 with other materials like MgO, ZnO, Al2O3 and CaCO3. In this study, plasmonic DSSCs were fabricated using MgO coated SnO2 (SnO2:MgO) based photoanodes incorporating gold nanoparticles (Au NP) having the size in the 30 – 35 nm range and sensitized with ruthernium N719 dye. Photoanodes were characterized by UV–VIS spectroscopy and the DSSCs were characterized by current–voltage (J–V) measurements, incident photon-to-electron conversion efficiency (IPCE) measurements and electrochemical impedance spectroscopy (EIS). Under the illumination of 100 mW cm−2 (AM 1.5), the efficiency (η) of the reference DSSC with pristine SnO2 photoanode was 1.52%, where as the efficiency of the optimized plasmonic DSSC with Au NP incorporated SnO2:MgO photoanode (Au: SnO2:MgO) was an impressive 4.69%. This efficiency enhancement of about 208% compared to the reference DSSC appears to be due to the increased open-circuit voltage (VOC) of 725.6 and increased short-circuit photocurrent density (JSC) of 9.06 mA cm−2 respectively evidently caused by the reduced electron recombination by ultra-thin MgO barrier layer and the enhanced light harvesting caused by the local surface plasmon resonance (LSPR) effect due to Au nanopraticles. EIS analysis showed that the incorporation of plasmonic Au metal nanoparticles leads to a decrease in the series resistance (RS) and the interfacial charge-transfer resistance (RCT) at the SnO2/electrolyte interface.

The influences of Ni, Ag-doped TiO2 and SnO2, Ag-doped SnO2/TiO2 nanocomposites on recombination reduction in dye synthesized solar cells

In this work, the effects of doped nanoparticles (NPs) and nanocomposites (NCs) such as SnO2/TiO2 NCs, Ni-doped TiO2 NPs, Ag-doped TiO2 NPs and Ag-doped SnO2/TiO2 NCs as photoanode on the performance of Dye synthesized Solar Cells (DSSCs) were studied. The compounds were successfully synthesized using hydrothermal and sol-gel methods. XRD was used to examine the crystalline structures and the effects of dopants and nanocomposites on the crystal form of TiO2. Moreover, FE-SEM and TEM analysis showed that the produced NPs and NCs were porous and their shape, size and dispersion degree were different. Furthermore, by using FTIR spectra, the chemical species of the grown crystals were identified. Besides, variations band-gap were observed through the analysis of optical absorption spectra. In addition, EIS was used to analyze the effect of dopants and nanocomposites TiO2 on charge transfer resistance in the DSSCs. These studies indicated that the DSSCs photovoltaic properties largely depend on the compounds and structure of photoanodes. To this end, the current-voltage characteristics and Incident Photon-to-electron Conversion Efficiency (IPCE) measurements were used to evaluate the performance of DSSCs. As seen, while the conversion efficiency of the DSSC samples varies from 1.2 to ~6.93%, the DSSC-based on Ag-doped SnO2/TiO2 exhibit the highest conversion efficiency, i.e., 6.93%. It is owing to its lower charge transfer resistance, recombination and higher short-circuit photocurrent.

Simultaneous Enhancement of Charge Separation and Hole Transportation in a W:α-Fe2O3/MoS2 Photoanode: A Collaborative Approach of MoS2 as a Heterojunction and W as a Metal Dopant

In this study, a facile approach has been successfully applied to synthesize a W-doped Fe2O3/MoS2 core-shell electrode with unique nanostructure modifications for photoelectrochemical performance. A two-dimensional (2D) structure of molybdenum disulfide (MoS2) and tungsten (W)-doped hematite (W:α-Fe2O3) overcomes the drawbacks of the α-Fe2O3 and MoS2 semiconductor through simple and facile processes to improve the photoelectrochemical (PEC) performance. The highest photocurrent density of the 0.5W:α-Fe2O3/MoS2 photoanode is 1.83 mA·cm-2 at 1.23 V vs reversible hydrogen electrode (RHE) under 100 mW·cm2 illumination, which is higher than those of 0.5W:α-Fe2O3 and pure α-Fe2O3 electrodes. The overall water splitting was evaluated by measuring the H2 and O2 evolution, which after 2 h of irradiation for 0.5W:α-Fe2O3/MoS2 was determined to be 49 and 23.8 μmol.cm-2, respectively. The optimized combination of the heterojunction and metal doping on pure α-Fe2O3 (0.5W:α-Fe2O3/MoS2 photoanode) showed an incident photon-to-electron conversion efficiency (IPCE) of 37% and an applied bias photon-to-current efficiency (ABPE) of 26%, which are around 5.2 and 13 times higher than those of 0.5W:α-Fe2O3, respectively. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications.

ZIF-8 derived ZnO/TiO2 heterostructure with rich oxygen vacancies for promoting photoelectrochemical water splitting

Due to the serious recombination of electron-hole and weak photoresponse ability, achieving highly efficient photoelectrochemical (PEC) water splitting activity for TiO2 photoelectrode has become a key issue. In this paper, we reported a new method for preparing ZnO/TiO2 photoelectrodes by electrostatic adsorption from zeolitic imidazolate framework-8 (ZIF-8) as the precursor. ZIF-8 was combined with TiO2 nanorods (NRs) through electrostatic interaction and then calcined to obtain ZnO/TiO2 heterojunction photoelectrodes with abundant oxygen vacancies (Ovac). The introduced ZnO with Ovac provides a large number of active sites which enhanced the electrical conductivity and charges separation of ZnO/TiO2 photoelectrode. The optimal photocurrent density of ZnO/TiO2 photoelectrodes at 1.23 V versus (vs.) reversible hydrogen electrode (RHE) under illumination (100 mW/cm2) has reached 1.76 mA/cm2, almost 2.75 times that of the pure TiO2. Meanwhile, the incident photon-to-electron conversion efficiency (IPCE) of the best photoelectrode has increased to 58.2% at 390 nm, the charge injection (ηinjection) and separation (ηseparation) efficiency have reached to 93.53% and 51.62% (1.23 V vs. RHE), respectively.

Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells

Summary Understanding defects is of paramount importance for the development of stable halide perovskite solar cells (PSCs). However, isolating their distinctive effects on device efficiency and stability is currently a challenge. We report that adding the organic molecule 3-phosphonopropionic acid (H3pp) to the halide perovskite results in unchanged overall optoelectronic performance while having a tremendous effect on device stability. We obtained PSCs with ∼21% efficiency that retain ∼100% of the initial efficiency after 1,000 h at the maximum power point under simulated AM1.5G illumination. The strong interaction between the perovskite and the H3pp molecule through two types of hydrogen bonds (H…I and O…H) leads to shallow point defect passivation that has a significant effect on device stability but not on the non-radiative recombination and device efficiency. We expect that our work will have important implications for the current understanding and advancement of operational PSCs.