Efficient Dye-sensitized Solar Cells Research Articles

Characterization of Poly(vinylidene Fluoride) Nanofiber-Based Electrolyte and Its Application to Dye-Sensitized Solar Cell with Natural Dyes

The potential of dye-sensitized solar cells (DSSC) as an alternative to depleting fossil fuels has been investigated. To optimize performance and efficiency, the effectiveness of PVDF and PVDF nanofiber (NF) membrane-based electrolytes in suppressing solvent leakage and evaporation in liquid electrolyte systems was evaluated. SEM results for PVDF NF membranes showed the formation of a network with a three-dimensional structure with a diameter of 100–300 nm and an average thickness of 0.14 mm. The Infrared (IR) spectrum shows the electrolyte and polymer-PVDF interactions. Differential Scanning Calorimetry (DSC) curve shows the melting transition of PVDF NF 7.66% lower than PVDF. Efficiency and resistance of DSSC based on natural dyes as measured by multimeter and Electrochemical Impedance Spectroscopy (EIS) at a solar intensity of 100 mW/cm2 showed the highest efficiency of anthocyanin-based DSSC from telang (Clitoria ternatea L.) flower extract. Its use as a photosensitizer in an electrolyte system based on PVDF NF membranes resulted in an efficiency that was not significantly different from that of liquid electrolytes (1.69%).

Improved photoactivity of TiO2 photoanode of dye-sensitized solar cells by sulfur doping

The photoactivity of the photoanode determines the power conversion efficiency of dye-sensitized solar cells (DSSC). TiO2 has come up as a potential photoanode in DSSC but it has several drawbacks, including large trap density due to lattice defect that influences carrier transport, interfacial charge transfer, and carrier transport. Here we present an effective approach to improve the TiO2 photoanode photoelectrical properties by chalcogenide ion doping, i.e. sulfur (S), that compensates the oxygen vacancy in the TiO2 lattice, enhancing the photoactivity at the visible region, reducing trap density and increasing the photovoltaic process in DSSC device. S doping in the TiO2 lattice was achieved by thiourea treatment. Our result shows that the S doping improves the interfacial charge transfer and reduced the trap density, improving the carrier lifetime and power conversion efficiency. The champion device, S-doped TiO2 with 0.3 M thiourea treatment, produces the DSSC with power conversion efficiency as high as 4.56%, which is two times higher than the DSSC using pristine TiO2. The S doping should find a potential approach for enhancing the photoactivity of the TiO2 photoanode of the DSSC device.

Strategies to Improve the Photochromic Properties and Photovoltaic Performances of Naphthopyran Dyes in Dye‐Sensitized Solar Cells

AbstractSemi‐transparent solar cells are emerging as promising devices for building integrated photovoltaics. However, regardless of the technology considered, the optical transmission of semi‐transparent solar cells is fixed during the fabrication process, and hence, cannot adjust to variations in daylight or weather conditions. This becomes an issue when applications such as photovoltaic windows are envisioned. Previously, it has been reported that the use of photochromic naphthopyran dyes in dye‐sensitized solar cells (DSSC) allows for the fabrication of semi‐transparent devices capable of modulating their light transmission and energy production depending on light intensity. Herein, a series of naphthopyran dyes with an identical pi‐conjugated backbone and varying alkyl substituents is reported. Using this molecular engineering strategy, the control of the discoloration kinetics of the photochromic dyes and the reduction of undesirable recombination processes when utilised in solar cells is demonstrated. The clear photochromic‐photovoltaic structure‐property relationships for these new photosensitizers is established and they are shown to demonstrate improved photovoltaic performances and photochromic responses in DSSC with notably faster discoloration than previously reported. For the first time with photochromic molecules, the co‐sensitization of the electrodes is explored and the highest power conversion efficiency for a photochromic DSSC is reported, reaching up to 4.34% under standard conditions.

Potential Dye Suji Leaves (Pleomele angustifolia) Chlorophyll and Red Dragon Fruit Peel (Hylocereus polyrhizus) Anthocyanins as Natural Dyes for Dye-Sensitized Solar Cells

In this study, the quality analysis of chlorophyll and anthocyanin extraction dyes from suji (Pleomele angustifolia) leaves and red dragon fruit (Hylocereus polyrhizus) peel was extracted using ethanol as a natural dye for dye-sensitized solar cells (DSSCs). Dye characterization was carried out using UV-visible spectrophotometry to determine the wavelength absorption and bandgap using the Tauc plot method, electrochemical characterization of dye was carried out using cyclic voltammetry. The efficiency of DSSC was measured using a digital multimeter. In this study, chlorophyll was produced with absorption wavelengths at 663 nm and 439 nm while anthocyanin dye was at a wavelength of 532 nm. The bandgap of chlorophyll was calculated to be 2.51 eV and that of anthocyanins to be 2.1 eV using the Tauc plot method.. The electrochemical results shows that chlorophyll dye of suji leaves has HOMO energy (highest occupied molecular orbital) at -5.68 eV and a LUMO energy (lowest unoccupied molecular orbital) at -3.17 eV while anthocyanin has HOMO energy of -5.16 eV and a LUMO energy of -3.06 eV. The efficiency produced by DSSC with chlorophyll dye was 3.4163 × 10-3 % and anthocyanins were 6.3994 × 10-3 %. These results show that chlorophyll and anthocyanin dyes from suji leaves and red dragon fruit peel are promising reagents to be used as DSSC dyes.

A morphological study of bicontinuous concentric lamellar silica synthesized at atmospheric pressure and its application as an internal micro-reflector in dye-sensitized solar cells.

KCC-1, a nanostructured silica material with a bicontinuous concentric lamellar (bcl) morphology, provides plenty of functional characteristics, such as an open channel structure, excellent accessibility, and a large surface area. Although bcl silica exhibits various superior properties, studies on its morphology and its application in dye-sensitized solar cells (DSSCs) are still limited. Therefore, this work aims to study the influence of the synthesis time on the morphology of bcl silica. Moreover, we used the synthesized bcl silica as internal micro-reflectors in DSSCs. The bcl silica was synthesized using the reflux method by varying synthesis times. The morphology of bcl silica was observed using FESEM and HRTEM. FESEM images show that bcl silica has bicontinuous lamellar walls arranged concentrically to form spherical particles. As the synthesis time increases, the average particle size of bcl silica increases. The quantization of bcl silica binary images shows that the average lamellar cross-sectional area ratio decreases with increasing synthesis time. The simulation of the Cahn-Hilliard's spinodal decomposition model using MATLAB also describes the lamellar cross-sectional area ratio of bcl silica. In addition, to characterize the FESEM image's texture, a Shannon entropy calculation was performed. The line and circular gray value intensity profiles of the HRTEM image show that bcl silica has a denser core than the outer part. The denser core proves that the lamellae in bcl silica are concentrically arranged towards the particle core. Furthermore, we added bcl silica to a photoanode to see the effect of bcl characteristics on the DSSC performance. The results show that the bcl silica significantly improves the light-harvesting efficiency in DSSCs due to its low refractive index and open channel structure.

Performance of Rhodamine-Sensitized Solar Cells Fabricated with Silver Nanoparticles

A plasmonic effect of silver nanoparticles (AgNPs) in dye-sensitized solar cells (DSSCs) is studied. In this investigation, the efficiency of dye-sensitized solar cells has been remarkably increased by infusion of synthesized silver nanoparticles into the TiO2 photoanode. Rhodaminederivative RdS1 was synthesized by microwave-assisted condensation of hydrazide and 3-for-mylchromone. The synthesized silver nanoparticles were characterized with UV/Vis absorption spectroscopy and transmission electron microscopy. The interfacial charge transport phenomena of the dye-sensitized solar cell (DSSCs) are determined by electrochemical impedance spectroscopy and the corresponding efficiencies are calculated using current-voltage (I-V) curve. The solar cell photoanode with silver nanoparticles infused with RdS1 in titanium dioxide had the highest solar-to-electric power efficiency at 0.17%.

AuNRs attached TiO2 NPs modified by cobalt-imidazolate frameworks as exceptional materials to improve the energy conversion efficiency of dye-sensitized solar cells.

This work reports a significant improvement in both the open-circuit voltage (VOC) and current density (J) of dye-sensitized solar cells (DSSCs) using gold nanorod-modified TiO2 nanoparticles (TiO2/AuNRs) together with a cobalt-imidazolate framework (ZIF-67) as an efficient photoanode. It was demonstrated that adding ZIF-67 (8 wt%) to TiO2 NPs increased the VOC by 160 mV and J by 2.5 times. This observation was described based on the significant increase in the amount of adsorbed dye in the presence of highly porous ZIF-67, which boosts the photoanode's light harvesting. Modifying TiO2 NPs with AuNRs also caused a remarkable enhancement in J (∼ 2.8 times), which can be explained via electron transfer between the TiO2 conduction band and AuNRs. It can result in a more efficient inhibiting effect on the interfacial charge recombination processes in TiO2/AuNRs/ZIF-67 because of the formation of a Schottky barrier at the interface between TiO2 and Au. These effects were confirmed by the reduction in the photoluminescence intensity of TiO2 in the presence of AuNRs. More reduction in the photoluminescence intensity was observed when ZIF-67 was added. The prepared photoanode showed an outstanding improvement in the overall efficiency of the DSSC (η) to 8.38% compared to the bare TiO2-based photoanode (1.83%). The notable improvement in the TiO2/AuNRs/ZIF-67 performance confirmed its practicality for high-efficiency DSSCs.

Increasing the Efficiency Significantly of Dye-Sensitized Solar Cells based on ZnO Nanomaterial Photoanode by Doping Titanium

This work was conducted for fabrication of Dye Sensitized Solar Cells (DSSC) based on ZnO nanomaterials asphotoanode and Titanium (Ti) as a dopant material. The aims of this research are to see the effect of adding Ti to ZnOmaterials on optical, structural, morphological properties and on the efficiency of DSSC based on ZnO. The novelty of thiswork is the tunable properties of ZnO by varying Ti concentration (0.02 M, 0.04 M and 0.06 M). The properties of ZnOhave been analyzed using spectroscopy UV-Vis, X-ray diffraction (XRD), field emission scanning electron microscope(FESEM), and energy dispersive X-ray(EDX). The power conversion efficiency (PCE) of the DSSC was recorded from0.58% to 2.19%

Titanium Dioxide (TiO2) Doping Copper (Cu) with Annealing Temperature Variation as Photoanode for Dye-Sensitized Solar Cells (DSSC)

Cu-doped Titanium Dioxide (TiO2) has been widely used as a DSSC photoanode material. The annealing temperature affects the structural analysis and optical properties of DSSC photoanodes. Structural analysis showed that the crystal size increased with increasing annealing temperature. The XRD results showed that the sample formed an anatase phase at annealing temperatures of 300℃ and 400℃, while at 450℃ and 500℃ there was an anatase-rutile mixed phase. The results of SEM morphology data obtained average particle diameters for CT300, CT400, CT450, and CT500 materials were 23.87 μm, 32.54 μm, 33.38 μm, and 37.63 μm respectively. UV-Vis testing shows absorbance in the ultraviolet region at 350-400 nm. Increasing the annealing temperature decreases the absorbance. The efficiency of DSSC compared to undoped materials is 0.44% to 0.71% in samples with an annealing temperature of 300℃ which is the sample with the highest efficiency. The efficiency value decreased with increasing annealing temperature.

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.

Design and fabrication of mixed phase transition metal chalcogenide hybrid composite (M = Ni & Co) for Pt-free efficient dye-sensitized solar cell applications

Design and fabrication of mixed phase transition metal chalcogenide hybrid composite (M = Ni & Co) for Pt-free efficient dye-sensitized solar cell applications

D–π–A organic dyes derived from the indacenodithiophene core moiety for efficient dye-sensitized solar cells

Indacenodithiophene-core-based D–π–A-type organic sensitizers with two different donor antennas (triphenylamine and phenothiazine) were designed and synthesized for use as light-harvesting materials in dye-sensitized solar cell (DSSC) applications.

Design of an amorphous ZnWSe2 alloy-based counter electrode for highly efficient dye-sensitized solar cells

Amorphous ZnWSe2 alloy-based counter electrodes grown by magnetron sputtering technique can indeed possess superior optoelectronic properties, resulting in a substantial efficiency of 8.27% and prolonged photostability.

Enhancing of dye-sensitized solar cells efficiency using graphene - MWCNT nanocomposite as photoanode

TiO2/NC nanocomposite was prepared using hydrothermal method reaction for the effective distribution of TiO2 nanoparticles on carbonaceous materials. MWCNT was incorporated in a nanocomposite not only to prevent the restacking of graphene but also to increase the electron transfer from TiO2. The detailed characterization of the nanocomposite was performed using SEM and XRD due to the improved electron transfer and the higher adsorption for N719. It showed energy conversion efficiency (8.96%) which is good compared to pure TiO2 (8.147%). TiO2/NC nanocomposite was suitable as a photoanode in DSSC.

Tuning TiO2 Porosity of Multilayered Photoanode Towards Enhanced Performance of Dye Sensitized Solar Cell

In this paper, we prepared Titanium Dioxide (TiO2) based dye sensitized solar cells (DSSC). Downscaling of commercial TiO2 powder have been achieved by systematic ball milling carried out using home-made ball milling device. Thin films were prepared and samples were characterized by XRD, SEM, UV-Vis and I-V. The main objective of this work is to prepare TiO2 based (DSSC) using N3 dye and study the effect of the TiO2 grain size inside the photoanode layer on the efficiency of the solar cell. UV-vis study of nanometer sized TiO2 particles showed that the energy gab has shifted towards the lower wavelength in electromagnetic spectrum (blue shift), and then optical band gap is an indirect and allowed transition. Energy gap calculations of related grain size of showed quantum confinement effect. A sophisticated strategy for TiO2 films consisting of tailoring monolayer, bilayer and trilayer of mixed multisized nanoparticles were adopted and investigated as DSSC electrodes. Our results showed that the dye sensitized solar cells can be substantially altered due to the designs and the particle size distributions of the TiO2 photoelectrode. The maximum efficiency of 0.5% was reached by TiO2 photoelectrode designed as a trilayer with a particles of wide size distribution from about 12 to 340 nm in the middle layer. The approach of light scattering in submicrometer‐sized TiO2 nanoparticles aggregates was adopted in order to interpret the enhancement of our DSSC efficiency over extending the length transported by electromagnetic wave hence to promote the light acquiring efficiency of photoelectrode thin film. The relatively larger particle sizes afford the TiO2 films with both better packing and an increased capability for scattering of the incident electromagnetic wave, and hence improves our DSSC efficiency.

A Molecularly Tailored Photosensitizer with an Efficiency of 13.2% for Dye-Sensitized Solar Cells.

Photosensitizers yielding superior photocurrents are crucial for copper-electrolyte-based highly efficient dye-sensitized solar cells (DSCs). Herein, two molecularly tailored organic sensitizers are presented, coded ZS4 and ZS5, through judiciously employing dithieno[3,2-b:2″,3″-d]pyrrole (DTP) as the π-linker and hexyloxy-substituted diphenylquinoxaline (HPQ) or naphthalene-fused-quinoxaline (NFQ) as the auxiliary electron-accepting unit, respectively. Endowed with the HPQ acceptor, ZS4 shows more efficient electron injection and charge collection based on substantially reduced interfacial charge recombination as compared to ZS5. As a result, ZS4-based DSCs achieve a power conversion efficiency (PCE) of 13.2% under standard AM1.5G sunlight, with a high short-circuit photocurrent density (Jsc ) of 16.3mAcm-2 , an open-circuit voltage (Voc ) of 1.05V and a fill factor (FF) of 77.1%. Remarkably, DSCs sensitized with ZS4 exhibit an outstanding stability, retaining 95% of their initial PCE under continuous light soaking for 1000h. It is believed thatthis is a new record efficiency reported so far for copper-electrolyte-based DSCs using a single sensitizer. The work highlights the importance of developing molecularly tailored photosensitizers for highly efficient DSCs with copper electrolyte.

Molecular design and synthesis of acetohydrazonoyl cyanide structures as efficient dye-sensitized solar cells with enhancement of the performance of the standard N-719 dye upon co-sensitization

Four novel acetohydrazonoyl cyanide compounds (5–8) with a triphenylamine moiety as an electron donor for use in dye-sensitized solar cells (DSSCs) have been designed and synthesized. The target molecules and their intermediates were well characterized using various spectral techniques. Their absorption spectra and electrochemical and photovoltaic properties are extensively investigated and compared with N-719 dye. The photovoltaic efficiency of these new dyes under AM1.5 ranges from 1.91% to 5.17% without the use of any additive. Compound 8 achieved the highest photovoltaic conversion efficiency (PCE, η = 5.17%) among the existing dyes due to the high values of the photocurrent (JSC = 13.66 mA cm−2) and photovoltage (VOC = 647 mV). Due to the good results shown by compound 8, the compound was used as a co-sensitizer along with the N-719 dye to improve its properties and raise its efficiency. The results showed that using (0.2 mM of compound 8 + 0.2 mM of N-719) improved the performance of the fabricated cell (PCE, η = 8.63%) with the enhancement in both VOC (682 mV) and JSC (20.39 mA cm−2) compared to the cell fabricated with N-719 alone (PCE, η = 6.23%, VOC = 623 mV, JSC = 16.48 mA cm−2). Furthermore, electronic excitations simulated using time-dependent DFT agreed well with experimentally obtained sensitizer results, indicating that the exchange-correlation function and basis set used to predict the spectra of the co-sensitizers are quite appropriate for the calculations. In conclusion, the results showed the potential of simple organic co-sensitizers in the development of efficient DSSCs.

Electrochemical and spectroelectrochemical characterizations of phthalocyanines bearing peripherally tetra-4-carboxyethylenephenoxy anchoring groups and usage as photosensitizers of dye-sensitized solar cell

A series of metal-free and metallo phthalocyanines (MPc) peripherally substituted with tetra-4-carboxyethylenephenoxy (M = 2H+ (H2Pc), Co2+ (CoPc), Zn2+ (ZnPc), and TiO2+ (TiOPc)) are used as dyes in the dye-sensitized solar cells (DSSCs). To predict the feasibility of MPcs as photosensitizers, electrochemical and in-situ spectroelectrochemical characterizations are first carried out since their redox mechanisms and optical responses under electrochemical excitations are the key factor for the requirement of the photosensitizers in DSSCs. The redox activities and opto-electrochemical responses of the compounds make them promising dye candidates with electrochemically reversible and multi-electron electron transfer reactions and suitable HOMO-LUMO band positions. The DSSCs using TiO2 film modified with these MPcs are developed and characterized. DSSC analyses indicate that especially H2Pc and TiOPc among the MPcs illustrate better photovoltaic performances than the others. The increase in efficiency of DSSC consisting of H2Pc and TiOPc is mainly associated with their suitable band positions and high electron lifetimes. When compared with the Pc bearing various substituents, ethylenephenoxy linkers between the Pc ring and the carboxyl anchoring groups significantly enhance the push-pull features between the dyes and TiO2 semiconductor, which results in 1.15, 2.98, 3.17 and 3.97 % power conversion efficiencies with CoPc, ZnPc, H2Pc, and TiOPc based DSSCs respectively.

Charge Transfer as Bridging Correlator for DSSC Efficiency and NLO Property

AbstractThe efficacy of dipyridyl and diphenylamine sensitizers in dye‐sensitized solar cells (DSSCs) is linked to trends in DFT‐based charge transfer and non‐linear optical (NLO) properties. We chose DFT and Time‐dependent‐DFT methods. The planarity is improved by replacing the phenyl ring at the donor site with a thiophene ring. Similarly, cyanoacetic acid acceptor improves planarity over rhodamine‐3‐acetic acid acceptor. In all cases in HOMO, the electron density is located at the donor and some part of the spacer, and in LUMO, it is shifted to the acceptor. Bond length alternation, bond order alternation, quinoid character, effective charge transferred distance, effective charge transferred, chemical potential, electrophilicity index, and electron correlation descriptors showed direct relation, while hardness and hyperhardness showed an inverse relation with NLO properties. We observed higher β0 and γ for thiophene‐based sensitizers ranging from 248.81×10−30 to 440.92×10−30 esu and 777.82×10−36 to 1442.69×10−36 esu, respectively. Likewise, more negative values of ΔGinject (−0.630 to −0.752 eV), a smaller value of ΔGreg (0.662 to 0.790 eV), and higher LHE (0.959 to 0.976) are observed for thiophene‐based sensitizers. Also, thiophene‐based sensitizers showed shorter Ti−O bond lengths than their phenyl‐based sensitizers. Photovoltaic parameters are directly related to DSSC efficiency and NLO properties.

Study of Single Diode Model of DSSC Based on Reduced Graphene Oxide as Counter Electrode

We studied the characteristic of reduced graphene oxide (RGO) as a counter electrode (CE) in Pt-free dye-sensitized solar cell (DSSC) using single diode model equation based on current density-voltage (J-V) measurement. The electrical characteristics of DSSC was investigated by electrochemical impedance spectroscopy (EIS) in order to knowing the catalytic properties of RGO as counter electrode. The RGO thin film as CE was deposited on fluorine-doped tin oxide (FTO) substrate and stacked with FTO/TiO2/ruthenium dye/mosalyte/RGO/FTO DSSC structure. The RGO film was obtained from GO (graphene oxide) film that was thermally reduced at 200°C for one hour under argon flow. The performance of DSSC with RGO as CE was characterized by current-voltage measurement and the interface between each layer was observed by Electrochemical Impedance Spectroscopy (EIS). The device efficiency (η) of DSSC that used GO and RGO film as CE are 0.09% and 3.43%, respectively. DSSC parameters such as series resistance (RS) shunt resistance (RSH), and ideality factor (n) were obtained from J-V curve which analyzed using single diode model equation. All samples have a Rs value of 2 indicates that all devices have a good ohmic contact. The RSH of device using RGO-1mg/ml is increase (from 2850 to 3670 Ω.cm2) compared with GO indicate that thermal reduction is successes. The RGO film shows a comparable performance to Pt-conventional CE thus it is a good candidate as alternative of DSSC counter electrode.