Photoelectric Conversion Efficiency Of Dye-sensitized Solar Cells Research Articles

Accelerating ultrafast processes in hydrogen-bonded complexes under pressure

Acceleration of ultrafast processes is vital in hydrogen-bonded coumarin–methanol complexes for improving the photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs). The traditional methods expedite ultrafast processes individually related to electron injection in DSSCs, namely, internal conversion (IC) or intermolecular charge transfer (inter-CT), by adjusting molecular topologies. We introduce pressure as an external drive to realize the acceleration of both processes simultaneously without changing the configuration. In the definite hydrogen-bonded complexes, the acceleration of IC and inter-CT processes is visualized by in situ high-pressure femtosecond transient absorption spectroscopy. In liquid-phase methanol, the IC and inter-CT processes are actuated effectively from 150.20 to 59.21 fs and 93.95 to 29.05 ps, respectively. The quickening of both processes is attributed to the enhancement of intermolecular hydrogen bonds under pressure. After the pressure-induced methanol phase transition, the rates of IC and inter-CT processes at 3.67 GPa are increased by 36.42% and 80.55% compared to at 1.00 atm. Our study results open an enlightening avenue for boosting the photoelectric conversion efficiency of DSSCs.

Graphene Quantum Dots as a Co-Sensitizer With Improving Light Absorption for Dye-Sensitized Solar Cells

We improve photovoltaic performance by incorporating graphene quantum dots (GQDs) into dye-sensitized solar cells (DSSCs). GQD can emit green fluorescence (∼530 nm) in the ultraviolet wavelength range (∼340 nm), and this characteristic is applied to enhance the light absorption ability of N719 dye. Using GQDs as auxiliary sensitizers to achieve co-sensitization with N719 dye can enhance the photovoltaic performance of DSSCs. We observed the photoresponse characteristics of DSSCs with different sensitization effects by incident photon-to-current conversion efficiency (IPCE). According to the results, the photoelectric conversion efficiency of DSSCs using the GQD+N719 co-sensitized photoanode was increased to 5.14%, which is a 20% improvement.

Preparation of Heteromorphic Ni Decorated Fe‐Containing Carbon Nanofibers as Efficient and Low‐Cost Counter Electrodes for Dye‐Sensitized Solar Cells

AbstractIn the field of dye‐sensitized solar cells (DSSCs), although Pt is commonly used as counter electrode materials owing to its great electrocatalytic activity and conductivity, the high price and small reserves of Pt limit its large‐scale application. In this paper, heteromorphic Ni decorated Fe‐containing carbon nanofibers (Ni/NiO@Fe‐CNFs) was prepared by a thermal synthesis method, and applied as composite counter electrode materials for DSSCs. It was found that the as‐synthesized Ni/NiO@Fe‐CNFs shows better electrocatalytic activity than that of Fe‐CNFs and CNFs for the reduction reaction of triiodide to iodide. The improved electrocatalytic activity is not only attributed to the introduction of Fe2O3 to form Fe‐CNFs, but also attributed to the heteromorphic Ni decoration and their synergistic effect. The photoelectric conversion efficiency of DSSCs with Ni/NiO@Fe‐CNFs counter electrode is 4.81 %, much higher than that of CNFs (0.62 %) and Fe‐CNFs counter electrode (3.65 %), and comparable to the value of Pt counter electrode (5.10 %). Accordingly, the Ni/NiO@Fe‐CNFs is expected to be a potential counter electrode material to replace Pt.

Heterostructured CoTe2/g-C3N4 nanocomposite thin film counters electrodes for enhancing the photovoltaic performance of dye-sensitized solar cells

In this study, dye-sensitized solar cells (DSSCs) were created by using CoTe2 modified g-C3N4 nanosheets as counter electrode materials. CoTe2 has an orthorhombic crystalline structure (JCPDS No. 74-0245) and independent spherical shaped morphology sizes in the range of 25–35 nm, which is further distributed evenly on the surface of g-C3N4 in the CoTe2/g-C3N4 composite films, according to XRD and TEM results. UV and PL spectroscopic experiments were used to examine the optical band gap and charge transfer utilization of the fabricated films. The experimental results demonstrated that after being modified with g-C3N4, the photoelectric conversion efficiency of DSSCs was clearly improved. The DSSC with 5 wt% CoTe2 incorporated g-C3N4 CE exhibits high PCE of 7.41 %, which is 2.1 times better than that of bare CoTe2 (3.89 %). Moreover, the CoTe2/g-C3N4 showed high electrocatalytic activity and longer electron life time, which is confirmed by CV, EIS and Tafel polarization experimental studies.

The TiO2 films with sandwich-type polyoxometalates in dye sensitized solar cells with electron recombination decreasing and dye adsorption increasing

Unfavorable electron recombination, which hinders the efficiency of dye-sensitized solar cells (DSSCs), usually occurs at the TiO2/dye/electrolyte interface on a photoanode. Polyoxometalates (POMs), as good electron acceptors, can be used as electron-transfer materials in DSSCs to improve electron transport in TiO2 and reduce electron recombining on the interface of a photoanode. In this paper, the pure inorganic sandwich-type POM Na9[Na3(H2O)6Cu3(H2O)3(SbW9O33)2]·40H2O (Cu3Na3POM) was mixed with TiO2 to form nanocomposites by simple sol-gel method. X-ray photoelectron spectroscopy (XPS) proved that Cu3Na3POM and TiO2 combined. Then the nanocomposite was doped with P25 to form Cu3Na3POM@TiO2/P25 photoanodes which were applied to the DSSCs. The Cu3Na3POM improved the transfer and recombination of electrons in the photoanode, proved by open circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) and ultraviolet-visible (UV-vis) absorption spectra showed that Cu3Na3POM optimized the morphology of the photoanode and the adsorption capacity of dye. The electrochemical test showed that the photoelectric conversion efficiency of DSSCs with Cu3Na3POM@TiO2/P25 photoanodes was enhanced to 6.91%, which was 13.66% higher than the DSSCs without Cu3Na3POM.

Preparation of ZnO compact layer using vacuum ultraviolet for dye-sensitized solar cells

Vacuum ultraviolet (VUV) light with a wavelength of 172 nm has the capacity to convert the oxygen contained metal organic precursor into metal oxide. Here, zinc acetate precursor thin film is directly converted into ZnO thin film by the irradiation of 172 nm VUV light rather than the high temperature sintering. The converting processes were demonstrated by the measurements of FTIR, XRD, SEM and XPS. And then the effect of irradiating time on the morphology, thickness and transparence of the prepared ZnO thin films was discussed. The ZnO thin film was further used as the compact layer in the photoelectrode of dye-sensitized solar cell (DSSC) to suppress the recombination processes of photogenerated electrons on the conducting glass electrode. For the different irradiation times, the photoelectric conversion efficiency of DSSC based on the compact layer prepared by the irradiation for 30 min is the highest reaching 10.27%, which is also higher than that of DSSCs without the compact layer and even with the compact layer prepared by the high temperature sintering. The uniform, dense, pinhole-free and amorphous ZnO thin film on the conducting glass substrate can be successfully prepared using the VUV irradiation technology for the compact layer of DSSCs.

Enhanced Efficiency of Dye-Sensitized Solar Cells Based on Polymer-Assisted Dispersion of Platinum Nanoparticles/Carbon Nanotubes Nanohybrid Films as FTO-Free Counter Electrodes.

In this study, polymer-assisted dispersants are used to stabilize the nanohybrids of platinum nanoparticles (PtNPs)/carbon nanotubes (CNTs) through non-covalent bond forces. These dispersants aim to replace the florine-doped tin oxide (FTO) glass in traditional dye-sensitized solar cells (DSSCs) as counter electrodes. The large specific surface area, high conductivity, and redox potential of PtNPs/CNT nanohybrids are used as the basis to utilize them as the counter electrode material to fabricate a dye-sensitized solar cell. The conductivity results indicate that the resistance of the PtNP/CNT nanohybrid film can be reduced to 7.25 Ω/sq. When carbon nanotubes are mixed with platinum nanoparticles at a weight ratio of 5/1, the photoelectric conversion efficiency of DSSCs can reach 6.28%. When using the FTO-containing substrate as the counter electrode, its conversion efficiency indicates that the micro-/nano-hybrid material formed by PtNPs/CNTs also exhibits an excellent photoelectric conversion efficiency (8.45%) on the traditional FTO substrate. Further, a large-area dye-sensitive cell is fabricated, showing that an 8 cm × 8 cm cell has a conversion efficiency of 7.95%. Therefore, the traditional Pt counter electrode can be replaced with a PtNP/CNT nanohybrid film, which both provides dye-sensitive cells with a high photoelectric conversion efficiency and reduces costs.

In situ solvothermal growth of Cu2ZnSnS4 thin film for counter electrode of dye-sensitized solar cells

Quaternary Cu2ZnSnS4 (CZTS) nanocrystalline thin films were in situ grown on FTO coated conductive glass by a low cost solvothermal method. The effect of the reaction time and the concentration of precursor solution on the purity and morphologies of the deposited thin films was studied. The morphology, crystal structure and composition of the deposited thin films were characterized by scanning electron microscope, high resolution transmission electron microscope, X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray spectroscopy. The pure wurtzite CZTS nanoparticles can be formed as the reaction time is 20 h. The film prepared at the optimized precursor solution concentration has uniform thickness, smooth surface and tight binding between the nanoparticles. The performance of the deposited CZTS thin films used as the counter electrode for dye-sensitized solar cells (DSSCs) was evaluated by measuring photocurrent density-voltage curves of DSSCs, electrochemical impedance spectroscopies and Tafel polarization curves of the symmetric cells. Photoelectric conversion efficiency of DSSC based on the optimized CZTS counter electrode reached 6.19%. The excellent photoelectric performance is attributed to the better surface morphology and conductive skeleton of the prepared CZTS thin film. The in situ solvothermal preparation method of the CZTS thin films for counter electrode of DSSCs is green, low cost and simple.

Cause, Regulation and Utilization of Dye Aggregation in Dye-Sensitized Solar Cells.

As an important member of third generation solar cell, dye-sensitized solar cells (DSSCs) have the advantages of being low cost, having an easy fabrication process, utilizing rich raw materials and a high-power conversion efficiency (PCE), prompting nearly three decades as a research hotspot. Recently, increasing the photoelectric conversion efficiency of DSSCs has proven troublesome. Sensitizers, as the most important part, are no longer limited to molecular engineering, and the regulation of dye aggregation has become a widely held concern, especially in liquid DSSCs. This review first presents the operational mechanism of liquid and solid-state dye-sensitized solar cells, including the influencing factors of various parameters on device efficiency. Secondly, the mechanism of dye aggregation was explained by molecular exciton theory, and the influence of various factors on dye aggregation was summarized. We focused on a review of several methods for regulating dye aggregation in liquid and solid-state dye-sensitized solar cells, and the advantages and disadvantages of these methods were analyzed. In addition, the important application of quantum computational chemistry in the study of dye aggregation was introduced. Finally, an outlook was proposed that utilizing the advantages of dye aggregation by combining molecular engineering with dye aggregation regulation is a research direction to improve the performance of liquid DSSCs in the future. For solid-state dye-sensitized solar cells (ssDSSCs), the effects of solid electrolytes also need to be taken into account.

A new (3,6)-connected silver(I) coordination polymer with photovoltaic performance

Under solvothermal conditions a new coordination polymer, [Ag(L)0.5]n (1) (H2L = azobenzene-4,4′-dicarboxylate), has been obtained successfully. Complex 1 has a three-dimensional (3D) framework structure with (3,6)-connected {4.62}2{42.610.83} topology. The co-sensitization of complex 1 and Ru-bipyridine dye (N719) increases the absorption of the dye-sensitized solar cells (DSSCs) in the ultraviolet region. When the illumination intensity is 100 mW cm−2, the photoelectric conversion efficiency of DSSC (complex 1/N719/TiO2) can reach to 3.14%. The result shows that the DSSC (complex 1/N719/TiO2) possessed excellent photovoltaic performance. Moreover, fluorescent property was also investigated.

One-step synthesis of nitrogen-decorated CeO2/reduced graphene oxide nanocomposite and its electrocatalytic activity for triiodide/iodide reduction

Abstract

A rational design of excellent light-absorbing dyes with different N-substituents at the phenothiazine for high efficiency solar cells.

Dye-sensitized solar cells (DSSCs) have attracted great interest due to their simple fabrication process and low cost. However, most organic dyes with D-π-A configuration usually exhibit narrow absorption band, leading to poor light harvesting ability and great loss on photon conversion efficiency. In this research, a series of excellent light-absorbing dyes (CC202-I - CC202-III) with different N-substituents at phenothiazine entities based on the champion dye CC202 were designed and investigated by density functional theory (DFT) and time-dependent DFT (TD- DFT). According to the analysis of absorption property, the results demonstrated that different N-substituents (12-crown-4-substituted phenyl, 4-hexoxyphenyl, and bare phenyl) at phenothiazine entities lead to stronger and broader absorption band as well as red-shifted spectra; moreover, larger electronic injection driving force (ΔGinject), regeneration driving force (ΔGreg), capability of light harvested (ηLHE(λstrong)/η-LHEλ) and maximal photon generated current (Jph) in CC202-I - CC202-III are observed compared to that of CC202, which further increase JSC. Additionally, a larger VOC can be obtained in CC202-I - CC202-III due to larger dipole moment (unormal) and slow electron recombination rate. Considering the all calculated characteristics related to JSC and VOC, dyes with 12-crown-4-substituted phenyl, 4-hexoxyphenyl, and bare phenyl substituent on phenothiazine can effectively enhance the photoelectric conversion efficiency of DSSCs.

Significant enhancement of the performance of dye-sensitized solar cells with photoelectrode co-doped graphene and hybrid SiO<sub>2</sub>@Au nanostructure

Attributed to facile fabrication, low production costs and outstanding photoelectric properties, dye-sensitized solar cells (DSCs) have attracted widespread attention in recent years. In order to achieve better photoelectric conversion efficiency of the DSCs, a series of TiO<sub>2</sub> nanocomposite photoanodes co-doped with different amounts of hybrid SiO<sub>2</sub>@Au nanostructures and certain amount of graphene are prepared by a mechanical ball milling method. The influence of SiO<sub>2</sub>@Au nanostructures and graphene on the performance of the photoanodes and their DSCs were investigated. The Au nanoparticles can remarkably enhance the short-circuit current density (<i>J</i><sub>sc</sub><italic/>) due to the local surface plasmon resonance effect of the noble metal nanoparticles. As a unique two-dimensional material, graphene has several amazing characteristics, such as high specific surface area and excellent conductivity. Studies showed that by introducing both SiO<sub>2</sub>@Au nanostructures and graphene, the light-absorbing, electron mobility and dye loading of the photoanodes were remarkably increased. Experimental results indicated that in comparison with those DSCs based with pure TiO<sub>2</sub> photoanode, the DSCs with photoanodes incorporated with SiO<sub>2</sub>@Au nanostructures and graphene showed the optimal performance with short-circuit current density (<i>J</i><sub>sc</sub><italic/>) of 15.59 mA/cm<sup>2</sup> and photoelectric conversion efficiency (PCE) of 6.68%, increasing significantly by 15.67% and 8.8%, respectively. This significant enhancement in <i>J</i><sub>sc</sub><italic/> and PCE of DSCs are mainly attributed to the increase in light-absorption and dye-loading of the photoanodes due to the hybrid SiO<sub>2</sub>@Au nanostructures and graphene.

A simple method to synthesize low-cost carbon modified TiO2 counter electrodes for high-efficiency dye-sensitized solar cells

Low cost and stable counter electrodes (CE) for dye-sensitized solar cells (DSSC) are promising for widespread use. In this paper, we report a simple and effective method to synthesize carbon modified TiO2 (TiO2/C) thin film as an abundant low cost CE for high-efficiency DSSC. The TiO2 paste layer contained organic compound was deposited on FTO glass substrate by a screen-printing method. When annealing the TiO2 paste layer at 450–550 °C under Ar flow, these organic compounds are decomposed to carbon to form carbon coated TiO2 nanoparticles. When used as a CE of DSSCs, the experimental results point out that the photoelectric conversion efficiency of DSSCs was obviously improved to near that of the referenced Pt CE. For TiO2/C is one of the cheapest and most stable materials, this TiO2/C can be used as a low cost CE for large scale high efficient DSSCs.

Application of sandwich-type polyoxometalates modified TiO<sub>2</sub> in dye-sensitized solar cells

<p indent=0mm>Nowadays, the rapid consumption of fossil energy has led to global energy shortage. At present, more than 80% of the energy consumed globally is derived from non-renewable fossil fuels such as coal, oil and natural gas. The burning of fossil fuels will also bring about a series of problems such as the greenhouse effect, the falling quality of global air, the formation of acid rain and the pollution of water bodies. Therefore, whether new energy sources that can replace fossil energy can be found has become an increasingly popular concern problem. Dye-sensitized solar cells (DSSCs) as a new type of renewable energy source have attracted wide attention in recent years, because of their simple fabrication process, low production costs, relatively high photoelectric conversion efficiency (PCE), and being environmentally safe. But the recombinations of photogenerated electrons holes are seriously affected the photoelectric conversion efficiency of DSSCs. Polyoxometalates (POMs) are a class of metal oxide clusters with the highest oxidation state of tungsten, molybdenum or vanadium. Due to their structural diversity and unique physicochemical properties, they have been applied in catalysis, photochemistry, biology and medicine. However, due to POMs have excellent photoelectrochemical properties, which can be used as an excellent electronic extractant in the photoanode of DSSCs. Here, the sandwich-type polyoxometalates compound K₁₅{K₃[(A-α-PW₉O₃₄)₂Fe₂(C₂O₄)₂]}·29H₂O with the intramolecular electron transfer properties is composited with TiO₂ by sol-gel method to prepare a POM@TiO₂ composite photoanode. The energy band structure of the polyoxometalate is studied by optical and electrochemical measurements. The result shows that the LUMO energy level <sc>(-0.06 V)</sc> of the sandwich-type polyoxometalates is lower than that of TiO₂ and the optical band gap is <sc>2.28 eV.</sc> The performance test shows that the DSSC efficiency of POM@TiO₂ composite photoanode production reached 6.33%, which is 15% higher than that of battery whose anode is pure TiO₂ (5.52%). Electrochemical impedance spectroscopy (EIS), dark current tests and voltage decay curve tests demonstrate that sandwich-type POMs effectively suppress electron-hole recombinations and increase electron lifetime. The incident monochromatic photon-electron conversion efficiency (IPCE) test further demonstrates that the introduction of the POMs increases the monochromatic conversion efficiency (from 35% to 53%).

Electrocatalytic Properties of MoS2 In-situ Grown on Graphene Oxide as Counter Electrode for Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have attracted great attention as one of next-generation photovoltaic devices due to low cost and simple fabrication process. A conventional DSSC consists of TiO2 photoelectrode, counter electrode (CE) and liquid electrolytes containing iodide/triiodide (I/I3 -) redox couple sandwiched between the electrodes. The CE serves to collect electrons and catalyze redox couple regeneration; thus, its material and performance determine the cost and photoelectric conversion efficiency of DSSC. Generally, noble Pt is employed as a CE owing to its rapid electron transfer ability and superior electrocatalytic behavior toward I3 - species. However, Pt is expensive and limited in resource. Hence, it is vital to find inexpensive and readily available non-Pt catalysts for the development of DSSCs. Carbon materials, conductive polymers, transition-metal compounds, metal alloys, and their composites have been explored to replace Pt. Among these alternatives, transition-metal compounds including carbides, nitrides, chalcogenides and oxides have demonstrated some desirable performances. MoS2 consists of three atom layers: one Mo layer sandwiched between two S layers via weak Vander Waals interactions. Advantageously, MoS2 has abundant exposed active sulfur edges for catalytic activity. On the other hand, graphitic carbon nitride (g-C3N4) demonstrates excellent thermal and chemical stability as well as interesting electric properties, which make it have good catalytic activity for a variety of reactions. In addition, g-C3N4 can be economically prepared in large scale. Herein, we present the fabrication and characterization of porous g-C3N4 nanosheet/MoS2 nanoparticle (g-C3N4/MoS2) composite. Such an architecture can provide short diffusion distance for excellent charge transport as well as large contact area for fast interfacial charge separation and electrochemical reactions. As a result, the nanocomposite is anticipated to exhibit good electrochemical and catalytic activities. In this study, we first developed a solution-based coating method to prepare g-C3N4/MoS2 counter electrode. Through a facile hydrophilization process for g-C3N4 and sintering the Mo-S precursor coated g-C3N4 at 280 °C for 12 h, crystalline MoS2 nanoparticles were formed on g-C3N4 substrate, resulting in strong mechanical adhesion. In addition, low-cost solution-processed g-C3N4/MoS2 electrode had similar electrocatalytic behavior toward I3 - species to Pt. As a result, the DSSC based on g-C3N4/MoS2 demonstrates desirable photovoltaic performance.

A Novel Way for Improving the Overall Photoelectric Conversion Efficiency of Dye Sensitized TiO2 Solar Cells

The past several years has witnessed a sharp increase in the number of scientists and researchers who have attached great importance to studying Dye sensitized solar cells (DSSCs) because of its low cost and potential high photoelectric conversion efficiency. There are two main factors that influence the photoelectric conversion efficiency of dye sensitized solar cells. One is the low photon absorption rate of solar cells, and other one is the low transmission rate of the photo-generated electrons through the thick nanocrystalline film. So in order to further research and improve efficiency, an accurate model using COMSOL Multiphysics is investigated to reveal the photoresponse and current transport processes of DSSC. Specifically, an optical model is studied to determine how much the solar energy each cell takes in, and an electrical model is investigated to determine how much the overall efficiency. Besides, three adjusted micro/nanostructures of DSSCs have been built for improving the efficiency. The study shows that a more suitable structure can collect more solar energy and improve the electronic diffusion efficiency so as to improve the overall photoelectric conversion efficiency of DSSC.

Fabrication and Experimental Investigation on Dye Sensitized Solar Cells Using Titanium Dioxide Nano Particles

Dye sensitized solar cell (DSSC) has received more and more attentions from academia and industry in the past two decades through continuous research and development, though the photoelectric conversion efficiency of DSSC has exceeded 11% for cell using titanium dioxide nano particles (Nano TiO2) and pomograntes juice as dye, but still about two times lower than silicon cell technology. To overcome this limitation, the vast research studies developed highly efficient DSSCs by the material breakthroughs and has a current record of 15% efficiency,encouraging the research activity for an economically viable photovoltaic system.In this paper, dye-sensitized solar cells (DSSC) have been fabricated on fluorine-tin-oxide (FTO) glass substrates, in which Nano TiO2 electrodes have been printed with different amount on 3 different cells .

Highly-ordered arrays of TiO2 thin film for dye-sensitized solar cells fabricated by anodic oxidation process

Highly ordered arrays of TiO2 photoelectrode thin films of dye-sensitized solar cells (DSSCs) were fabricated by anodic oxidation method. This study analyzed the effects of electrolytes under similar NH4F concentrations but different reaction times in the anodic oxidation process on the photoelectric conversion efficiency of DSSC, open-circuit voltage decay, electron lifetime, and incident photon-to-electron conversion efficiency (IPCE) of the prepared DSSC. Experimental results show that the TiO2 nanotube thin film prepared by anodic oxidation with an electrolyte with a NH4F concentration at 0.5 wt% and with a reaction time of 5 hr can be fabricated with a length of 17 μm and a photoelectric conversion efficiency of 4.87%, open-circuit voltage of 0.74 V, and short-circuit current density of 13.2 mA/cm2. Additionally, the same NH4F concentration but with a reaction time of 10 hr achieves a length of 22 μm and a photoelectric conversion efficiency of 6.58%, open-circuit voltage of 0.81 V, and short-circuit current density of 16.1 mA/cm2.

G-C3N4 modified TiO2 nanosheets with enhanced photoelectric conversion efficiency in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) were fabricated by using g-C3N4 modified TiO2 nanosheets (CTS) as photoanode materials in this research. A thin layer of g-C3N4 was coated on the surface of TiO2 nanosheets by simply heating the mixture of TiO2 nanosheets and urea, which led to the formation of TiO2@g-C3N4 nanosheet heterostructure. The experimental results showed that the photoelectric conversion efficiency of DSSCs was obviously improved after modified by g-C3N4. The measurements of I–V characteristic indicated that the introduction of g-C3N4 could increase both the open circuit voltage and short-circuit photocurrent density. Along with the analysis of electrochemical impedance spectroscopy, it is considered that the thin layer of g-C3N4 can act as the blocking layer for electron backward recombination with electrolyte, which can be used as the functional material to increase the DSSC performance.