Zinc Oxide Photoelectrode Research Articles

Influence of GO and rGO on the structural and optical properties of ZnO photoelectrodes for energy harvesting applications

Due to excellent physical and chemical performances, graphene and its derivatives dominate the industrial and academic research aiming the commercialization, more specifically in optoelectronics-based energy harvesting. Owing to high electron movability, a lot of interest is shown in utilizing the zinc oxide (ZnO) as photoelectrode in such applications. In this study, graphene oxide (GO) and reduced graphene oxide (rGO) are synthesised through a simple modification of Hummer's method. ZnO:GO and ZnO:rGO composite thin films are deposited on glass substrates using the spin coating method. The structural, optical, and electrical properties are investigated in detail. The Fourier-transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) are used to determine the structure of the prepared films, which confirmed the presence of oxygen functionalities and the hexagonal wurtzite crystal structure. The increasing GO and rGO weight percentage has resulted in increasing the crystallite size, and in turn, decreased the resistivity. All the films exhibit transmittance around 90 % in UV–Visible region, which make them useful as an optical window in optoelectronic applications. The surface microstructure of the GO and rGO inserted samples are analysed using a high-resolution electron microscope.

High Performance Dye Sensitized Solar Cells by Plasmonic Enhancement of Silver Nanoparticles in ZnO Photoelectrode with Betanin Pigment

Metal nanoparticles (NPs) introduced in sensitive places in Dye Sensitized Solar Cells (DSSCs) has demonstrated superior performance due to surface plasmon resonance effect. Herein, a systematic investigation by introducing plasmonic silver nanoparticles (AgNPs) in the photoanode of DSSCs with Zinc oxide (ZnO) is investigated. The broadening of the absorption band in the visible region is made possible using the natural pigments betanins. The combined effect of UV-visible absorption spectroscopy, XRD technique, SEM and solar simulator were used to explore the surface plasmon resonance effect. The ZnO photoanode without Ag- NPs shows a Power Conversion Efficiency (PCE) of 0.156 %, Current Density (Jsc) of 0.477 mAcm-2, Open Circuit Voltage (Voc) of 0.762 V and Fill Factor (FF) of 0.431. On coating AgNPs on the pristine photoanode, the PCEs were improved significantly as compared with the pure ZnO based device. The AgNPs were deposited in cycles (2 cycles, 4 cycles and 6 cycles). The device with 2 cycles of Ag NPs, shows a PCE of 0.373 % which demonstrates an enhancement of 2.39 times to that of the prestine device.Also depositing 4 cycles of AgNPs results to PCE of 0.290 % which shows a leading of 0.134 % ahead of the reference PCE. With 6 cycles of AgNPs deposited on the photoanode of bare ZnO NPs, it results to PCE of 0.244%, FF of 0.592, Jsc of 0.572 mAcm-2 and Voc of 0.722 V which also shows an enhancement of - 1.56 times, 1.37 times and 1.20 times in PCE, FF and Jsc over the device lacking AgNPs. These results show significant increment in performances of all the devices with silver inclusion. The performance is attributed to the reduced recombination of electron–hole pairs due to the Ag-ZnO junction and the generation of intense electric fields at the immediate vicinity of the sensitizer, resulting in enhanced light absorption.

Hybrid photoanode of TiO2-ZnO synthesized by co-precipitation route for dye-sensitized solar cell using phyllanthus reticulatas pigment sensitizer

We report synthesis and characterization of hybrid photoanode made up of Titanium Dioxide (TiO2) and Zinc Oxide (ZnO) nanoparticles prepared by a co-precipitation process. Though TiO2 is the most preferred anode for Dye Sensitized Solar Cell (DSSC), the charge recombination between electrode and electrolyte poses a major challenge. ZnO photoelectrode is a potential alternative due to higher carrier mobility but has a slower electron injection than TiO2. To maximize the benefits of both, a co-precipitation synthesis of TiO2/ZnO is proposed in this work as a promising alternative. The co-precipitation process produces metal oxides TiO2 and ZnO and eventually yields the Anatase TiO2 and Wurtzite ZnO. The experimental investigations of the new co-precipitation process show improved control of particle size, shape, and uniform distribution of ZnO and yet preserve the economy and simplicity of synthesis. The study shows an average crystallite size of 10 nm to 22 nm for TiO2 and 17 nm to 35 nm for ZnO. Wurtzite phase varies from 4.5% to 10.8% in a co-precipitated photoanode. The deconvolution of the typical Photoluminescence (PL) curve shows two distinct bands for ZnO and TiO2 cantered around 390 nm and 460 nm. The study shows that the co-precipitated TiO2/ZnO has a bandgap of less than 3.2 eV, this paves the way for reduced recombination and improved device performance. Further, we fabricated a prototype of a DSSC using photoanode of TiO2/ZnO and a sensitizer of natural plant pigment extracted from Phyllanthus reticulatas and successfully tested the prototype DSSC.

Optimization of a Zinc Oxide Photoelectrode for Dye-Sensitized Solar Cells

In this study, the influence of the seed-layer thickness of photoelectrodes on the performance of dye-sensitized solar cells was investigated. Al-doped ZnO films deposited on fluorine-doped tin oxide substrates by using facing targets sputtering systems of various thicknesses were used as seed layers, and ZnO rod array photoelectrodes were synthesized on the AZO seed layers via the hydrothermal process. The crystallinity of the ZnO photoelectrode was improved, and the average diameter of the ZnO rod increased from 100 ± 10 to 250 ± 10 nm as the thickness of the seed layer increased from 200 to 600 nm. The maximum fill factor, open-circuit voltage, current density, and power conversion efficiency of the ZnO rod array photoelectrode with a seed layer of thickness 600 nm were 31.08%, 0.53 V, 5.53 mA/cm2, and 0.91%, respectively.

Investigation of Strain Effects on Photoelectrochemical Performance of Flexible ZnO Electrodes

In this report, the growth of zinc oxide (ZnO) nanocrystals with various morphologies, nanoflower, nanosheet, and nanorod, on flexible stainless steel (SS) foils to be utilized as photoanodes in photoelectrochemical (PEC) solar cells has been presented. It has been aimed to provide flexibility and adaptability for the next generation systems with the incorporation of SS foils as electrode into PEC cells. Therefore, physical deformation tests have been applied to the prepared ZnO thin film photoanodes. These thin films have been thoroughly characterized before and after straining for better understanding the relationship between the morphology, straining effect and photoelectrochemical efficiency. We observed a notable increase in the maximum incident photon-to-current efficiency (IPCE) and durability of all ZnO photoelectrodes after straining process. The increase in IPCE values by 1.5 and 2.5 folds at 370 nm has been observed for nanoflower and nanorod morphologies, respectively after being strained. The maximum IPCE of 69% has been calculated for the ZnO nanorod structures after straining. Bending of the SS electrodes resulted in the more oriented nanorod arrays compared to its flat counterpart, which improved both the light absorption and also the photo-conversion efficiency drastically. The finite-difference time-domain simulations have also been carried out to examine the optical properties of flat and bent ZnO electrodes. Finally, it has been concluded that SS photoanodes bearing ZnO semiconducting material with nanoflower and nanorod morphologies are very promising candidates for the solar hydrogen generator systems in terms of efficiency, durability, flexibility, and lightness in weight.

Carbon Black and Titanium Interlayers Between Zinc Oxide Photo Electrode and Fluorine-Doped Tin Oxide for Dye-Sensitized Solar Cells.

Carbon black and titanium interlayers were deposited on fluorine-doped tin oxide (FTO) anode layers using radio frequency magnetron sputtering method. On top of them, Zinc oxide (ZnO) photo anode layers were prepared using plasma enhanced chemical vapor deposition technique. ZnO high binding energy as well as good breakdown strength, cohesion, and stability used as a photo electrode material for dye-sensitized solar cells (DSSC), but it does not have a good electrical contact to the FTO anode. To solve this problem, the carbon black and titanium interlayers were deposited. The effect of interlayers on the power conversion efficiency (PCE) of DSSCs was investigated. The PCE of the devices with 120-nm-thick interlayers of carbon black or titanium was 5.21 or 4.45%, respectively, which were larger than the PCE of the devices without such interlayers (3.25%). The smooth interface of the carbon black interlayer reduced the interface impedance of the ZnO photo anode effectively. On the other hand, the titanium interlayer with TiO₂ on the ZnO side increased the impedance, and decreased the PCE.

Linkage modification of a zinc oxide photoelectrode prepared with polyethylene glycol for electron transport improvement in dye-sensitized solar cells

The purpose of this study is to synthesize ZnO aggregate films using simple precipitation with polymer modification for linkage improvement of the ZnO photoelectrode. The starting materials of zinc acetate solution and ammonia solution were mixed under violent stirring conditions. A portion of the polymer (polyethylene glycol) was slowly added into the mixed solution to obtain the viscous ZnO precursor. The precursor was then coated onto a fluorine-doped tin oxide substrate and annealed to form ZnO films. The scanning electron microscopy results revealed the formation of ZnO aggregates with flower-like microstructures. The appearance of Zn and O elements indicated a fair ZnO formation. The X-ray diffraction patterns and Raman shift confirmed the hexagonal wurtzite crystal structure of the ZnO aggregates. For dye-sensitized solar cell (DSSC) application, power conversion efficiency was enhanced because of the improved photovoltaic characteristics including the open-circuit voltage, fill factor, series resistance, shunt resistances and recombination resistance, perhaps, due to the large particle size of the ZnO aggregates and their flower-like microstructures. The flower-like microstructure likely acts as a bridge to link each ZnO particle. The flower-like microstructure plays the role of an express pathway in electron transport in the DSSC. Therefore, the ZnO aggregation with a flower-like microstructure has the potential to improve the electron transport for efficiency enhancement of a DSSC.

Cu‐doped CdS QDs for sensitisation in solar cell

Copper (Cu)-doped cadmium sulphide (CdS) quantum dots (QDs) sensitised zinc oxide photoelectrodes have been fabricated for a solar cell (SC). For the synthesis of QDs, simple chemical methods have been adapted and the QDs were prepared on poly-vinyl alcohol capping agent. The influences of doping on structural properties of QDs have been studied using X-ray diffraction analysis and transmission electron microscopy images. Ultraviolet-visible absorption spectroscopy reveals an enhanced optical absorption in doped QDs. The photovoltaic performance of the Cu-doped CdS QDs was studied by measuring the current density-voltage ( J-V ) characteristics of the fabricated SC. An enhanced photo-conversion efficiency was observed in doped CdS QDs compared with the undoped QDs sensitised SC.

Nanostructured zinc oxide photoelectrodes by green routes M-SILAR and electrodeposition for dye sensitized solar cell

Surfactant-free, ultrasound assisted modified successive ionic layer adsorption and reaction (M-SILAR) method and home-made microcontroller based low-cost potentiostat system are employed to prepare zinc oxide (ZnO) nanostructure based thin films. The comparison between physicochemical as well as photoelectrochemical (PEC) properties of the nanostructures prepared via two different template free, simplistic and cost-effective green routes have been discussed in detail. X-ray diffraction and Raman analysis confirm the formation of phase pure ZnO with the hexagonal crystal structure. Surface morphology significantly affects the physicochemical as well as PEC properties of ZnO thin films. Nanorods (NRs) and nanosheets (NSs) based ZnO thin films sensitized with N3 dye have been directly used as photoelectrodes in the dye-sensitized solar cell (DSSC). The power conversion efficiency (PCE) of 0.59% is achieved with Jsc of 4.04 mA/cm2 and Voc of 0.44 V for the DSSC in which the M-SILAR deposited 1-D ZnO NRs based thin film is used as the photoanode. While relatively less PCE of 0.29% with Jsc of 2.53 mA/cm2 and Voc of 0.36 V is obtained for DSSC prepared using electrodeposited 2-D ZnO NSs. In the NSs like 2-D surface morphology, the presence of multiple grain boundaries are acted as traps for the diffusing electrons, which reduces the electron mobility through it.

Cadmium sulfide coated zinc oxide photoelectrode: Preparation and characterization

Cadmium sulfide (CdS) coated zinc oxide photoanode is prepared using two step deposition processes at relatively low temperature. The zinc oxide (ZnO) were deposited on the conducting glass substrates using doctor blade technique followed by the coating of CdS over ZnO at room temperature using chemical bath deposition method. In the present article, we are using three different types of CdS (bulk and nano forms) prepared by using chemical route. The size of the CdS was controlled using different concentration of capping agent during preparation. The samples were characterized by optical absorption, X-ray diffraction, scanning electron microscopy techniques. Further, the photoelectrochemical (PEC) performance of ZnO with CdS was tested in polysulfide electrolyte. When the CdS nanoparticles were coated on the ZnO, the optical absorption is enhanced and band edge is shifted towards visible region (from 470 to 525 nm) as compared with zinc oxide (375 nm). The device with CdS nanoparticles (type-b) shows higher photoelectrochemical (PEC) performance showing maximum short circuit current density (Jsc) of 1.51 mA/cm2 along with maximum electron life time (25.2 ms).

Chemical vapor treatment of zinc oxide photoelectrodes for efficiency enhancement of dye-sensitized solar cells

ZnO photoelectrodes were successfully treated using hydrochloric vapor. The vapor was generated from hydrochloric acid solution with sonication assistance. The morphology showed a formation of plate-like structures after the vapor treatment, resulting in light scattering which was observed in terms of increased reflectance compared with the non-treated photoelectrodes. A dye-sensitized solar cell fabricated with the treated photoelectrodes exhibited an enhanced power conversion efficiency of 3.00% in comparison to the non-treated photoelectrodes base of 2.35%. The enhanced power conversion efficiency was observed in direct relation to the increased short-circuit current density. The increased short-circuit current density is due to the achieved light scattering in the photoelectrodes. Moreover, an extended open-circuit voltage was observed due to reduced electron recombination in the device. Therefore, a chemical vapor treatment of ZnO photoelectrodes via hydrochloric acid resulted in a successful scattering layer formation and a reduced recombination process for power conversion efficiency enhancement of ZnO dye-sensitized solar cells.

Enhanced Photoelectrochemical Performance of Nanostructured Zinc Oxide Photoelectrodes Via Morphology Control

Photoelectrochemical solar cells (PEC) provide both harvesting and storage of the solar energy by converting it to chemical energy. In other words PEC systems convert sunlight into fuels by means of electrochemical reactions [1]. Total system efficiency of the PEC is directly affected by the performance of the working photoelectrode and the counter electrode. Here we investigated the influence of the morphology of the zinc oxide (ZnO) nanostructured photoelectrodes on the efficiency. ZnO photoelectrodes with nano-film, nanowire, and urchin-like morphologies have been used as working electrode in the three-electrode in one compartment cell configuration. Nano-films (ZnO-NF), 60 nm thick, have been deposited on the indium tin oxide (ITO) coated glass via physical vapor deposition. These films were used as the seeding layer to grow the ZnO nanowire arrays (ZnO-NW) by chemical bath deposition (CBD). Finally we fabricated the urchin-like nanostructures (ZnO-UL) on fluorine doped tin oxide coated (FTO) glass substrates by again CBD technique. In order to increase the coverage and the adhesion of the urchin-like structures we modified the surface of the FTO via hydroxylation process [2]. These electrodes were labeled as ZnO-H-UL. As expected, the light absorption of the nanowire and urchin-like structures was superior to the nanofilms. Therefore, nanowire formation slightly increased the current density under illumination at VAg/AgCl=0V bias. On the other hand, current density increased approximately 103 times and reached to 3 mA/cm2 for the ZnO-H-UL samples compare to the nano-films. Another drastic change was observed for the photoresponse, which is a measure of photo-generated current in the system. In other words photoresponse of the electrode can be calculated from the ratio of Jill-Jdark to Jdark, where Jill is the current density under illumination and Jdark is the current density at dark. The maximum photoresponse of the ZnO-NF was 4.5 indicating almost no current change in dark and under illumination. However, this value was 55, 7.9x102, and 1.2x103 for ZnO-NW, ZnO-UL and ZnO-H-UL electrodes, respectively. Enhancement in the photo generated current density for the urchin like structure could be related with the better light absorption and longer electron lifetime. According to our best knowledge this is the highest photoresponse reported in literature. Efficiency of the ZnO electrodes was calculated using the well known applied bias photon-to-current efficiency (ABPE) definition [3]. ABPE of the ZnO-NF and NW electrodes was 0.09 and 0.32 %, respectively. Efficiency of the ZnO electrodes increased with formation of needle like structures on the spherical bases. 0.65 and 0.87 % ABPE was observed for ZnO-UL and H-UL nanostructures, respectively. One can determine the overall PEC device efficiency by the ratio between the energy of the produced hydrogen and the total energy spent to accomplish the water splitting reaction [4]. PEC solar cells produced using ZnO-H-UL photoanode had the overall device efficiency of the 2.5%. Better photoresponse, photo current density, and the device efficiency of the ZnO-H-UL electrodes compare to the other nanostructures made them very favorable in PEC systems as working electrodes.

Influence of Zn concentration and dye adsorption time on the photovoltaic performance of M-SILAR deposited ZnO-based dye sensitized solar cells

Abstract Zinc oxide (ZnO) thin films have been deposited with ultrasonic rinsing assisted modified successive ionic layer adsorption and reaction (M-SILAR) method. The effect of Zn concentration on the growth of ZnO films and power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) have been studied. The surface morphology changes from nanorods to the nanoflowers like structure as a result of coalescence of the nanorods. Also, the significant effect of the dye adsorption time of photoelectrodes on the overall PCE of ZnO based DSSCs has been investigated systematically. It is found that the chemical stability is the foremost issue for ZnO photoelectrode. The prolonged dye adsorption time is responsible for the deterioration of the ZnO nanostructure due to the formation of Zn2+/N3 dye aggregates. The DSSC prepared using photoelectrode of 0.1 M Zn concentration and dye loading time of 18 h exhibited a highest PCE of 0.70%, since it possesses well-defined 1D nanostructure which facilitates very low reverse saturation current density and longer electron lifetime.

Crystal facet engineering of ZnO photoanode for the higher water splitting efficiency with proton transferable nafion film

Zinc oxide (ZnO) is considered as an extraordinary photoanode with direct band gap and high charge mobility for solar light water splitting reaction, but it suffers from proton (H+) produced by the photo-oxidation reaction. In the current work, we demonstrate that the long term-stability of ZnO photoanode with the introduction of proton transfer media. Proton transferable polymer such as nafion allows favorable transport of the generated H+ ions from the surface of ZnO photoanode to electrolyte and results in an enhanced its stability. Nafion polymer film was coated on the surface of ZnO thin film photoanode with each selectively exposed (002), (100) and (101) facet. Especially, nafion film with (002) crystal facet ZnO photoanode showed 3.9mA/cm2 of the high photocurrent density and 0.3–0.6μmol/cm2 of high oxygen and hydrogen gas evolution for 2h. The photoelectrochemical performance of nafion coated (002), (100) and (101) facet oriented ZnO thin film photoanode increase the performance of water splitting reaction and stability of ZnO thin film were demonstrated as a development of high efficient ZnO photoelectrode. Present work suggests the strategy to fabricate the stable metal oxide photoelectrode with the high photoelectrochemical performance.

Compression of ZnO nanoparticle films at elevated temperature for flexible dye-sensitized solar cells

This article presents the fabrication of flexible zinc oxide (ZnO) based dye-sensitized solar cells (DSSCs). To get homogeneous compact ZnO photoelectrode, we introduce a new post-treatment technique, namely hot-compress method (compression at elevated temperature). For further improvement, titanium oxide (TiO2) nanoparticle at different percentage was added to the ZnO paste as a binder material. The performances of the cells were analyzed by i–v, UV–Vis NIR, external quantum efficiency (EQE), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM) image. The result implies that the proposed hot-compress method gives homogenous compact ZnO layer, which enhances the photogenerated electron density of the device. The surface morphology and photovoltaic performance data of the DSSCs confirm that the hot-compress method is better than the other conventional post-treatments. The addition of TiO2 with the ZnO paste as a binder material exhibited better adhesion as well as better photovoltaic performances compared to the DSSCs prepared by only ZnO. The highest power conversion efficiency (η) of 1.75% was obtained for the ZnO based cell prepared by the addition of 10% TiO2 along with hot-compress as a post-treatment. This efficiency value was higher compared to the conventional post-treated ZnO based DSSCs.

Improved Sensitization of Zinc Oxide Nanorods by Cadmium Telluride Quantum Dots through Charge Induced Hydrophilic Surface Generation

This paper reports on UV‐mediated enhancement in the sensitization of semiconductor quantum dots (QDs) on zinc oxide (ZnO) nanorods, improving the charge transfer efficiency across the QD‐ZnO interface. The improvement was primarily due to the reduction in the interfacial resistance achieved via the incorporation of UV light induced surface defects on zinc oxide nanorods. The photoinduced defects were characterized by XPS, FTIR, and water contact angle measurements, which demonstrated an increase in the surface defects (oxygen vacancies) in the ZnO crystal, leading to an increase in the active sites available for the QD attachment. As a proof of concept, a model cadmium telluride (CdTe) QD solar cell was fabricated using the defect engineered ZnO photoelectrodes, which showed ∼10% increase in photovoltage and ∼66% improvement in the photocurrent compared to the defect‐free photoelectrodes. The improvement in the photocurrent was mainly attributed to the enhancement in the charge transfer efficiency across the defect rich QD‐ZnO interface, which was indicated by the higher quenching of the CdTe QD photoluminescence upon sensitization.

Plasmon Resonance Enhanced Zinc Oxide Photoelectrodes for Improvement in Performance of Dye Sensitized Solar Cells

Nanocomposites of vertically aligned zinc oxide (ZnO) nanorod arrays incorporated with gold (Au) nanoparticles have been used as photoelectrodes to fabricate dye sensitized solar cells (DSSCs). Due to the surface plasmon resonance of the Au nanoparticles, the nanocomposite photoelectrodes demonstrate enhancement in the visible light absorption resulting in ~8% higher photocurrent compared to ZnO photoelectrode based DSSCs fabricated without any Au nanoparticles. In addition to the higher optical absorption due to the gold nanoparticles, a Schottky barrier forms at the ZnO/Au interface preventing the back electron transfer from the conduction band of the semiconductor nanorods to the redox electrolyte providing improvement in the charge separation at the nanocomposite photoelectrode. Upon incorporation of Au nanoparticles, the overall efficiency of the DSSC increased from 2.41% to 3.27%. The role of Au nanoparticles on the performance of the DSSCs for varying concentration of the Au nanoparticles as well as the post-growth annealing treatment of the nanocomposite photoelectrode is reported.

Lawsone Sensitized ZnO Photoelectrodes for Dye Sensitized Solar Cells

Innovations in materials technology in the fields of photovoltaics play an important role in the paradigm shift from fossil fuels to renewable energy sources. The use of solar energy is one of the most important problems in energy utilization. Dye sensitized solar cell (DSSC) technology has been recognized as a competitor to the well developed thin film solar cells. In the present investigation, we have fabricated a device using natural Lawsone (Heena) dye which was used to sensitize zinc oxide (ZnO) films. ZnO seed layer was deposited using chemical bath deposition and slurry was used to deposit ZnO films followed by sintering at 450°C for 30 minutes in air. Performance of nanostructure ZnO photoelectrode using lawsone dye as a function of residence time in the dye solution was studied. For 20 hour dye loading time, we were observed power conversion efficiency around 0.5% which is more as compared to 5 and 14 hours dye loading time.

Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV–Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (Isc=0.357mA) and open circuit voltage (Voc=0.48V). Direct band gap calculated by considering R & T values of ZnO thin films increases from 3.14–3.21eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

Enhance the performances of dye-sensitized solar cell by a new type of sensitizer to co-sensitize zinc oxide photoelectrode with ruthenium complex

We designed a new type of sensitizer for dye-sensitized solar cells based on ZnO photoelectrode. Three five-coordinate transition metal complexes [2,6-(ArN CMe) 2C 5H 3NMCl 2·nCH 3CN] ( M Zn, Cd, Hg) (named as Zn1, Cd1, Hg1), have been synthesized. In all complexes, the metal center is tridentately chelated by the ligand and further coordinated by two chlorine atoms, resulting in distorted trigonal bipyramidal geometry. The improvement in conversion efficiency of dye-sensitized solar cell was achieved by the complexes ( M) and N719 co-sensitizing ZnO photoelectrode. In the tandem structure of M/N719/ZnO, the M forms a re-organization of energy level due to its single-crystal structure, which is advantageous to the electron injection and the hole recovery. The result demonstrates the M/N719 co-sensitized solar cell exhibited excellent photovoltaic performances with the short-circuit photocurrent density of 8.943 mA cm −2, the open-circuit photovoltage of 591 mV and the fill factor of 0.639 under standard global AM 1.5 solar irradiation conditions.