Counter Electrode For Dye-sensitized Solar Cells Research Articles

Bi 2 S 3 can do it all: Sensitizer, counter electrode, and supercapacitor for symmetric solar cell assisted photo‐supercapacitor

The current research motivation is to fabricate and demonstrate Pt-free dye-sensitized solar cells (DSSCs) at a low-cost and an electrode for supercapacitor. In this study, a well-known sensitizer in quantum dot solar cells, that is, Bi2S3 and Bi2S3/MWCNT hybrids have been synthesized and positioned as an electrocatalyst for the reduction of triiodide to iodide ( I 3 − / I − $$ {I}_3^{-}/{I}^{-} $$ ). Developed DSSC cell-based on Bi2S3/MWCNT counter electrode (CE) achieves a power conversion efficiency of 4.8%, surpassing the corresponding Bi2S3 CE (1.06%) where the efficiency of the present CE yields ~83% of the conventional Pt CE efficiency (~5.8%). In addition, a series of electrochemical investigations reveal that the Bi2S3/MWCNT outperformed the pristine Bi2S3 in terms of electroconductivity and electrocatalytic behavior. This mixture is also favorable for supercapacitors and Bi2S3/MWCNT has the maximum specific capacity of 133 F g−1 with 1 A g−1 in 0.5 M of Na2SO4 with the acceptable capacitance retention of around 80% for 3000 cycles and excellent rate capability (48 F g−1 at 5 A g−1). Besides, the symmetric cell, that is, TiO2/Bi2S3/( I 3 − / I − $$ {I}_3^{-}/{I}^{-} $$ )/Bi2S3 has been manufactured and tested successfully. Thus, Bi2S3 is not only a substitute for the conventional Pt-based CE in DSSCs but also can be a potential energy storage material and sensitizer for photo-supercapacitor applications.

Enhanced Performance of Carbon-Selenide Composite with La0.9Ce0.1NiO3 Perovskite Oxide for Outstanding Counter Electrodes in Platinum-Free Dye-Sensitized Solar Cells.

For large-scale applications, dye-sensitized solar cells (DSSCs) require the replacement of the scarce platinum (Pt)-based counter electrode (CE) with efficient and cheap alternatives. In this respect, low-cost perovskite oxides (ABO3) have been introduced as promising additives to composite-based CEs in Pt-free DSSCs. Herein, we synthesized composites from La0.9Ce0.1NiO3 (L) perovskite oxide and functionalized-multiwall-carbon-nanotubes wrapped in selenides derived from metal-organic-frameworks (f-MWCNT-ZnSe-CoSe2, “F”). L and F were then mixed with carbon black (CB) in different mass ratios to prepare L@CB, F@CB, and L@F@CB composites. The electrochemical analysis revealed that the L@F@CB composite with a mass ratio of 1.5:3:1.5 exhibits better electrocatalytic activity than Pt. In addition, the related DSSC reached a better PCE of 7.49% compared to its Pt-based counterpart (7.09%). This improved performance is the result of the increase in the oxygen vacancy by L due to the replacement of La with Ce in its structure, leading to more active sites in the L@F@CB composites. Moreover, the F@CB composite favors the contribution to the high electrical conductivity of the hybrid carbon nanotube–carbon black, which also offers good stability to the L@F@CB CE by not showing any obvious change in morphology and peak-to-peak separation even after 100 cyclic voltammetry cycles. Consequently, the corresponding L@F@CB-based device achieved enhanced stability. Our work demonstrates that L@F@CB composites with a low cost are excellent alternatives to Pt CE in DSSCs.

Brick Shaped Vanadium Nitride/Graphene Nanocomposite as Highly Efficient Counter Electrode Catalyst for Pt Free Dye‐Sensitized Solar Cell

AbstractA Platinum free hybrid counter electrode (CE) Vanadium nitride/graphene (VNGp) for dye‐sensitized solar cell (DSSC) was synthesized by hydrothermal method. The surface morphology and chemical composition of the as‐prepared VNGp composite were analyzed by X‐ray diffraction (XRD) analysis, Raman spectroscopy, high‐resolution electron transmission microscopy (HR‐TEM), and cyclic voltammetry (CV). The VNGp hybrid counter electrode displayed an adsorption‐controlled process towards the (I−/I3−) redox couple at CE/electrolyte interface and the value was calculated to be 3.16×10−9 mol/s by varying the scan rate. The exchange current density (Jo) was calculated as 6.59 mA/cm2 from the Tafel slope. The VNGp hybrid counter shows a maximum fill factor (FF) of 66.28 with high efficacy of 8.15 % under the illumination of 100 mW/cm2 as compared to the Pt CE for DSSC.

N-doped W2C derived from polyoxotungstate precursors by pyrolysis along the temperature gradient as Pt-free counter electrode in dye-sensitized solar cells

The counter electrodes (CEs) as the basic components of dye-sensitized solar cells (DSSCs) mainly use Pt-based catalysts. It is still an urgent need to decrease the assembled cost of DSSCs by designing high-performance and low-cost Pt-free materials to replace the scarce and expensive Pt as CEs catalyst. How particularly striking are that specific precursors were prepared by ball-grinding with polyoxotungstate (H 3 PW 12 O 40 ) as metal source and melamine (C 3 N 3 (NH 2 ) 3 ) as carbon source and nitrogen source, and then the pyrolysis process of precursors were dynamically controlled along the temperature gradient to make the auxiliary groups leave, so as to obtain the expected N-doped W 2 C catalytic materials. Herein, four kinds of N-doped W 2 C materials have derived from polyoxotungstate precursors at the pyrolysis temperatures of 700, 800, 900 and 1000 °C, and further applied to assemble CEs catalysts in DSSCs. The high power conversion efficiencies (PCE) of 6.10, 7.01, 5.95 and 5.34% were obtained for the regeneration of traditional iodide/triiodide (I 3 − /I − ), respectively. The enhanced performance of N-doped W 2 C materials can be attributed to the larger number of catalytic active sites, which was due to the higher specific surface area provided by pyrolysis and carbonization of organic complex precursor, and the activation and modification of materials by the N-doped and the high temperature. • N-Doped W 2 C derived from the pyrolyzed precursors of H 3 PW 12 O 40 with C 3 N 3 (NH 2 ) 3 . • There is the highest PCE of 7.01% of N-Doped W 2 C (obtained at 800 °C) as CEs in DSSC. •N-Doped W 2 C materials are a prospective alternative of Pt-free CEs in DSSCs.

Thin layer of nano nomposite RGO COMOS as a counter electrode on Dye Sensitized Solar Cell (DSSC)

This research aims to synthesis of GO using the Hummer method and the effect of adding CoS(Cobalt Sulfide) and CoMoS(Cobalt Molybdenum Sulfide) Nano composites to RGO as a counter electrode of DSSC. RGO doped CoMoS and RGO doped CoMoS was synthesis using solvothermal method by adding nanocomposite CoS and CoMoS to GO by heating 200˚C. RGO CoMoS powder was formed into a paste by stirring and adding a polymer binder. The paste was deposited onto the FTO glass substrate by the slip casting method so that a thin sheet was obtained on the substrate and applied as a counter electrode on the DSSC. This composite will be measured and tested for the morphology of its layer using SEM and tested for electrical properties with Keithley I-V meter. The additional of CoS and CoMoS may cause the changes crystal size of RGO. RGO CoMoS has higher efficiency than GO and RGO. Thin film of RGO CoMoS can be used of counter electrode DSSC that has Voc= 0,39volt, fill factor (FF) 34,32% and η= 1,54%.

Designing highly effective mesoporous Carbon-based counter electrodes for liquid Electrolyte-based and Quasi-solid Dye-sensitized solar cells

In this study, nitrogen-doped mesoporous carbon (NMC) and boron-doped mesoporous carbon (BMC) are synthesized and used as Pt-free counter electrode (CE) materials for dye-sensitized solar cells (DSCs). The optimized NMC and BMC CEs exhibit significantly higher catalytic activities than the pristine mesoporous carbon (MC). The I-/I3- in acetonitrile liquid electrolyte-based DSCs have power conversion efficiencies (PCE) of 7.20% with the NMC CE and 7.15% with the BMC CE, which are significantly higher than that obtained using the MC CE (5.88%). This is attributed to the improved effective catalytic active sites and the enhanced electrical conductivities of the NMC and BMC CEs. When Pt with trace amounts (0.1 wt%) is loaded on NMC, the liquid DSCs using Pt/NMC composite CEs yield PCE values of 8.31% and 9.92%, respectively, under 1.0 Sun and 0.1 Sun illumination. The Pt/NMC CE is further employed in quasi-solid DSCs, which also give a high PCE of 8.15% under 1.0 Sun illumination. A flexible Pt/NMC CE is also prepared on indium tin oxide-polyethylene naphthalate (ITO-PEN) substrate, and the generated liquid DSCs show a PCE of 6.92%. This work provides a feasible path to enhance the catalytic activity of the MC CE in DSCs.

Preparation of CoNi@CN composites based on metal-organic framework materials as high efficiency counter electrode materials for dye-sensitized solar cells

In this paper, Co-based metal organic framework mixtures (MOFs) stuff are used as self-sustain templates to prepare CoNi alloys and N-codop porous carbon composites (CoNi@CN) by one-step calcination and ion exchange methods and apply to the study of the counter electrode (CE) of dye-sensitized solar cells (DSSCs). CoNi@CN retains a large specific surface area, high porosity and abundant unsaturated sites of MOFs, and the conductivity and catalytic activity of porous carbon are improved by the introduction of CoNi alloy and N. At the same time, the nitrogen-doped porous carbon protects the CoNi alloy from corrosion of the electrolyte and ensures the stability of the material. CoNi@CN is used in DSSCs for catalytic reduction of I3- exhibits the photoelectric conversion efficiency of 8.85%, that is overtop the exhibited by Pt CE under the equal conditions. Therefore, CoNi@CN composites are prepared based on MOFs are expected to instead of Pt as DSSCs CE materials because of their excellent optoelectronic properties and inexpensive.

Facile and functional synthesis of Ni0.85Se/Carbon nanospheres with hollow structure as counter electrodes of DSSCs

• Hollow Ni 0.85 Se/C nanospheres were synthesized by one-pot solvothermal method. • The resultant Ni 0.85 Se/C displays excellent electrochemical properties. • As CE in DSSC, the Ni 0.85 Se/C exhibits superior photoelectric performance to Pt. Dye-sensitized solar cells (DSSCs), which can make efficient use of solar energy, have attracted extensive attention worldwide. Counter electrodes (CEs) of DSSCs play an essential role in controlling I 3 - reduction, thus determining electrocatalytic activity. Accordingly, a facile solvothermal approach was utilized to synthesize Ni 0.85 Se nanospheres with the existence of glucose as carbon source (Ni 0.85 Se/C), serving as CEs. Compared with the unsupported Ni 0.85 Se, the Ni 0.85 Se/C nanospheres exhibited superior electrochemical properties owing to the addition of carbon from glucose and existence of hollow as well as mesoporous structures, even outperforming those of the precious platinum electrode. The overall power conversion efficiency of the DSSC with the Ni 0.85 Se/C CE attained 9.39%, exceeding that with the Ni 0.85 Se (8.47%) and platinum CEs (8.77%).

The modified W2C@C composites derived from the polyoxotungstate-based organic complexes assisted by pyrrole for efficient counter electrode in dye-sensitized solar cells

The modification and doping on the surface of transition metal compounds (TMCs) substitute for conventional Pt as counter electrode (CEs) catalysts that are a distinguishing route to reduce the cost and improve the power conversion efficiencies (PCE) of dye-sensitized solar cells (DSSCs). In this study, polyoxotungstate (H3PW12O40)-based organic complex assisted by different amounts pyrrole as precursor to prepare W-based carbide. Exploiting four different W2C@C composites derived from the determined concentration co-precursor with pyrrole amounts of 0.05, 0.10, 0.15 and 0.20 mL under high-purity N2 flow at the temperature 800 °C. The effects of different amounts pyrrole on the catalytic activity of as-prepared W2C@C composites were investigated by corresponding electrochemical experiments. As indicated from the results, the W2C@C composites by the additional pyrrole as an carbon source and nitrogen source in the pyrolysis process that can improve the uniformity of particle dispersion, promote the number of active sites, and provide more dispersed voids, and then achieved PCEs of 6.28, 6.76, 7.08 and 6.34% for iodide redox couple regeneration in the assembled DSSCs, respectively, suggesting a potential competent substitutes for the noble metal CEs in DSSCs.

Dye-sensitized solar cell using nickel sulfide-reduced graphene oxide counter electrode: Effect of sulphur content

The influence on sulphur content in term of thiourea (TU) concentration on the properties of nickel sulphide (NiS)-reduced graphene oxide (rGO) has been reported in this paper. The effect of sulphur content on the performance of dye-sensitized solar cell (DSSC) using NiS-rGO counter electrode (CE) has also been investigated. The source of sulphur is TU. The sample has been prepared via modified Hummers’s method assisted with spin coating technique. The cell using NiS-rGO CE prepared with 1.20 M TU yielded the highest power conversion efficiency (η) of 1.42%. This is due to this cell has the lowest series resistance (Rb) and charge transfer resistance at the interface of NiS-rGO CE/electrolyte (Rct) with the value of 0.44 and 4.09 Ω, respectively. It is also due to the sample with 1.20 M TU owns the highest reduction current (J). The finding of this work reveals that NiS-rGO is able to substitute platinum as CE for DSSC.

Screen-printed carbon black/SiO2 composite counter electrodes for dye-sensitized solar cells

Platinum (Pt)-based counter electrodes (CEs) are promising electrocatalysts for dye-sensitized solar cells (DSSCs). However, replacing the expensive Pt with low-cost materials and comparable catalytic activity still a big challenge. Here, we prepared CB-SiO2 composites by blending various weights of SiO2 (1, 3, and 5 wt%) with carbon black (CB), followed by screen printed onto the FTO substrate to utilized as CEs for DSSCs. In comparison with pure CB, CB-SiO2 composite CEs showed higher transferability and higher electrocatalytic activity toward I3-/I- redox couple. Among all, CB-SiO2-1% composite CE with 4 µm showed the best catalytic performance, and the related DSSC showed a power conversion efficiency of 6.38%. Increasing the CE thickness significantly enhances the catalytic ability and the total performance of the assembled devices, whereas the power conversion efficiency of the DSSC with CB-SiO2-1% composite CE in 8 µm thick was 7.99%, which is close to that achieved by Pt-based device under the same conditions.

Effect of thickness on charge transfer properties of conductive polymer based PEDOT counter electrodes in DSSC

Poly(3,4-propylenedioxythiophene (PEDOT) counter electrodes are considered to be one of the most promising alternatives to expensive Pt-based counter electrodes in dye sensitized solar cells (DSSC). In the present study, we prepared PEDOT counter electrodes with various thicknesses through scalable electropolymerization technique using a nontoxic mixture of sodium dodecyl sulfate (SDC) in water medium, which provides the opportunity for scale up and commercialization. The time scale for electropolymerization was varied systematically to tune the thickness and uniformity of PEDOT film. The PEDOT films and their interaction with conventional iodide/triiodide​ (I−/I3−) electrolyte was studied using various electrical and optical characterization techniques. The catalytic activity of porous PEDOT films were found to be decreasing with an increase in thickness. DSSCs fabricated using PEDOT counter electrodes having lower thickness of 33 nm (deposited with 5 s polymerization time) showed superior power conversion efficiency of 10.39%, followed by PEDOT counter electrodes having 65 nm and 120 nm thickness deposited with polymerization time of 10 s and 15 s delivering power conversion efficiencies of 8.11% and 7.45% respectively. Electrochemical Impedance Spectroscopy (EIS) was used to investigate the role of variation in PEDOT thickness with various charge transfer processes at the electrolyte/counter electrode interface influencing PV performance.

Enhanced efficiency of DSSC by lyophilized tin-doped molybdenum sulfide as counter electrode

The influence of lyophilization on the electrochemical properties of hydrothermally synthesized tin (Sn) doped molybdenum sulfide (MoS2) nanostructures are investigated thoroughly. The lyophilized tin doped MoS2 used as counter electrode (CE) in dye-sensitized solar cells (DSSCs) showed high efficiency and better stability. Power conversion efficiency (PCE) of 7.14% is achieved using lyophilized 2.5% Sn-doped MoS2 as CE in DSSCs, which is much higher than devices made of CE comprising oven air annealed samples (5.74%). The major enhancement of PCE is due to the large surface area of Sn-doped lyophilized MoS2 nanostructures as well as the high electrocatalytic activity of MoS2 towards reduction reaction, which are observed from BET, CV and EIS measurements. Sequential CV scanning further showed the high electrochemical stability of the Sn-doped MoS2 nanostructures. This indicates the useful application of lyophilizer technique to produce various other metal sulfide nanostructures to increase the porosity and overall surface area of the materials for optimum device performance.

Low cost, platinum free counter electrode with reduced graphene oxide and polyaniline embedded SnO2 for efficient dye sensitized solar cells

A composite consisting of Reduced Graphene Oxide (RGO), Tin Oxide (SnO2) nanoparticles and Polyaniline (PANI) conducting polymer was studied as a potential counter electrode material for Dye Sensitized Solar Cells (DSSCs). This RGO/SnO2/PANI composite CE was fabricated by spray method and used as an alternative to Platinum (Pt) counter electrode (CE). In the fabrication of RGO/SnO2/PANI composite CEs, several optimizations were carried out to obtain the optimum RGO sintering temperature and the optimum amounts of RGO, SnO2 and PANI. The photovoltaic performance of the DSSCs based on the newly prepared CEs was studied by using I-V measurements. The efficiency of the DSSC with the CE with optimized RGO/SnO2/PANI composition having 9.8 μm thickness was 7.92% under the 100 mW cm−2 (1.5AM) light illumination. After the TiCl4 treated TiO2 photoanode was used, the maximum power conversion efficiency of the DSSC based on the RGO/SnO2/PANI composite CE was increased to 8.68%, which corresponds to an impressive 94% of the efficiency of 9.22% obtained for the control DSSC made with Pt CE and TiCl4 treated photoanode measured under same light illumination. These composite CEs were characterized by X-ray diffraction, Raman spectra, FTIR spectra, SEM and TEM. Cyclic voltammetry (CV) analysis showed the excellent electro-catalytic activity of the composite CE. With high energy conversion efficiency and improved charge-transfer process of DSSCs in combination with simple preparation and relatively low-cost technique, the RGO/SnO2/PANI composite electrode demonstrates the beneficial use of this novel composite material as CEs in DSSCs.

Large-scale synthesis of ultra-long sodium doped MoS2 nanotubes with high electrocatalytic activity

Large-scale production of high-quality molybdenum disulfide (MoS2) nanotubes is important due to their special structure and inherent properties. In this paper, we reported a low-cost approach to synthesize ultra-long Na doped MoS2 nanotubes on a large-scale by sulfurizing the precursors which produced by a hydrothermal method. Sodium chloride (NaCl) and ammonium molybdate solution are stirring in a heated water bath to prepare these precursors. Then Na doped MoS2 nanotubes are obtained by vapor-phase sulfurization using sulfur powder as S source. Transmission electron microscopy (TEM) images, X-ray diffraction (XRD) pattern, Raman spectra and X-ray photoelectron spectroscopy (XPS) prove the crystal structure of Na doped MoS2 with elemental composition of NaxMoS2 (x = 0.38–0.44). The morphology of the samples shows pure high-quality Na doped MoS2 nanotubes with length ranging from 100 to 300 µm. When used as the counter electrode (CE) of dye-sensitized solar cells (DSSCs), these nanotubes have excellent electrocatalytic activity. A power conversion efficiency of 5.85% is recorded in these solar cells, which is near that of the referenced Pt counter electrodes. This makes these nanotubes are ideal CEs of DSSCs. So this method is a simple and convenient approach to synthesize transition metal dichalcogenides (TMDs) nanotubes on a large scale.

Dual heteroatom-doped reduced graphene oxide and its application in dye-sensitized solar cells

The quick reduction and regeneration of the electrolyte (triiodide/iodide redox couple, I3−/I−) is one of the main issues in dye-sensitized solar cells (DSSCs). The well-known platinum counter electrodes (CEs) that facilitate electrolyte reduction and regeneration are very expensive; hence, low-cost and efficient CEs are in demand to substitute the platinum CEs. Herein, we report the hydrothermal synthesis of single (boron or nitrogen) and dual (boron/nitrogen mixture) heteroatom-doped reduced graphene oxide (rGO) and their comparison as CEs in DSSCs. The photovoltaic, electrochemical and conductivity properties were investigated. Dual heteroatom-doped rGO demonstrated a relatively large surface area and enhanced electrical conductivity (161.51 m2 g−1 and 22.07 S cm−1, respectively) when compared to graphene oxide (GO), rGO and single heteroatom-doped rGO. The amount of boron- and nitrogen-doping, including their configuration, played a crucial role in the catalytic activity. The presence of pyridinic-N and pyrrolic-N in single and dual heteroatom-doped rGO promoted a triiodide reduction reaction, which shifted the redox potential, relative to GO and rGO. The BN-rGO-3 CE yielded a relatively higher PCE of 2.97%, further enhanced to 4.13% when the BN-rGO-3 CE was used in conjunction with polyaniline as a binder. Therefore, this showed that dual heteroatom-doped rGO CEs enhanced the PCE of the DSSCs due to the synergetic effect, doping configuration and higher doping levels. Thus, the present work provides a facile and productive strategy for configuring the dual heteroatom-doped graphene CE materials with high electrocatalytic activity for energy conversion devices.

Efficient Iron Phosphide Catalyst as a Counter Electrode in Dye-Sensitized Solar Cells

Developing an efficient material as a counter electrode (CE) with excellent catalytic activity, intrinsic stability, and low cost is essential for the commercial application of dye-sensitized solar cells (DSSCs). Transition metal phosphides have been demonstrated as outstanding multifunctional catalysts in a broad range of energy conversion technologies. Here, we exploited different phases of iron phosphide as CEs in DSSCs with an I–/I3–-based electrolyte. Solvothermal synthesis using a triphenylphosphine precursor as a phosphorus source allows to grow a Fe2P phase at 300 °C and a FeP phase at 350 °C. The obtained iron phosphide catalysts were coated on fluorine-doped tin oxide substrates and heat-treated at 450 °C under an inert gas atmosphere. The solar-to-current conversion efficiency of the solar cells assembled with the Fe2P material reached 3.96 ± 0.06%, which is comparable to the device assembled with a platinum (Pt) CE. DFT calculations support the experimental observations and explain the fundamental origin behind the improved performance of Fe2P compared to FeP. These results indicate that the Fe2P catalyst exhibits excellent performance along with desired stability to be deployed as an efficient Pt-free alternative in DSSCs.

Enhanced electrocatalytic activity in dye-sensitized solar cells via interface coupling of the CoFe2O4/Co3Fe7 heterostructure

The DSSC assembled with CoFe/CFO CE exhibits a higher power conversion efficiency (8.54%), which surpasses that of conventional Pt (7.70%). Such excellent performance can be ascribed to the unique interfacial structural optimization and intimate interface coupling synergies. The original core-shell layer enriches the active sites, and further structural integration improves the interface, increasing the conductivity while synergistically accelerating the catalytic activity. • Synthesis of CoFe 2 O 4 /Co 3 Fe 7 hybrids by hydrothermal and impregnation methods. • Structural integration and multi-component synergy maximize catalytic activity. • DSSC based on CoFe 2 O 4 /Co 3 Fe 7 CE exhibited higher PCE (8.54%) than Pt (7.70%). The exploitation of high-efficient yet non-precious counter electrode (CE) materials is of great significance for practical applications of dye-sensitized solar cells (DSSCs). Herein, Co 3 Fe 7 alloy anchored on the porous core-shell CoFe 2 O 4 composites (CoFe 2 O 4 /Co 3 Fe 7 ) were successfully manufactured as a counter electrode for DSSC. The detailed electrochemical measurements verified that the introduction of Co 3 Fe 7 alloys modifies the original core-shell structure, contributing to enhance electrical conductivity and promote interfacial electron transfer. While the porous structure increases the potential for exposing active sites and accelerates the diffusion of iodide ions. Moreover, the formation of hetero-junction facilitates the generation of active facet sharing and multi-component synergy, thus prominently boosting the reduction of triiodide and accelerating reaction kinetics. As a consequence, DSSCs structured with CoFe 2 O 4 /Co 3 Fe 7 -modified CEs achieve a satisfactory power conversion efficiency (PCE) of 8.54%, which surpasses that of conventional platinum (7.70%). Meanwhile, the stability of CoFe 2 O 4 /Co 3 Fe 7 CE is also enhanced than noble metals platinum. This work highlights that the heterogeneous CoFe 2 O 4 /Co 3 Fe 7 with a rich interface can effectively stimulate the catalytic activity of reducing triiodide to enhance the performance of the solar cell. This strategy also paves the way for enhancing material activity in the field of energy storage and conversion.

A strategy of adopted Co4S3/Co2P2O7 composite grew on carbon paper to enhance the efficient of dye-sensitized solar cells

Metal phosphates have shown good hydrogen evolution reaction catalytic ability, but as counter electrode (CE) materials they are rarely used in dye-sensitized solar cell (DSSC). A strategy that introduction of Co2P2O7 as a “collaborator” to improve the catalytic performance of Co4S3 for the DSSC. The Co4S3/Co2P2O7 film grew on carbon paper (CP) was synthesized by using a hydrothermal route and vapor deposition method, and served as platinum-free (Pt-free) CE for DSSC. The composite materials of Co4S3/Co2P2O7 has many advantages of unique spherical morphology, large special surface area, more active sites and fast reaction kinetics for the reduction of I−/I3−. Under optimal conditions, a DSSC based on the Co4S3/Co2P2O7/CP CE achieves a high power conversion efficiency of 8.99%, which is comparable to that of the Pt (7.49%) and CoS1.097/CP (8.18%) CEs. The results indicate that the Co4S3/Co2P2O7/CP CE with the advantages of efficient and facile synthesis is a promising alternative to the expensive Pt CE for the DSSCs in the future.

Cu2ZnSnS4 thin film as a counter electrode in zinc stannate-based dye-sensitized solar cells

In this study, we deposited Cu2ZnSnS4 (CZTS) thin films with various thicknesses using electrodeposition and sputtering methods to exploit them as counter electrodes (CEs) in Zn2SnO4 -based dye-sensitized solar cells (DSSCs). The ternary Zn2SnO4 compound with wide bandgap energy, large corrosive resistivity, high electron mobility, and an appropriate conduction band edge position concerning the dye molecules (N719) can be an outstanding alternative for photoanode besides CZTS CE in DSSCs. On the other hand, CZTS is an impressive candidate as a CE material, but its electrocatalytic activity for the recovery of ionic species can be different depending on the synthesis process. Our results indicated the creation of porous morphology in the solution-based deposited films, which yields higher electrocatalytic activity in the CE performance in comparison with the physical deposition method, resulting in short circuit current densities of 9.77 and 8.40 mA cm−2 and open-circuit voltages of 633 and 583 mV for the DSSCs prepared by the respective techniques. The large active area and highly crystallized CZTS films, prepared by the electrodeposition method, led to an around 50% efficiency improvement compared to the widely used, more expensive platinum.