Dye-sensitized Solar Cells Devices Research Articles

Graphene Hybridized with Tungsten disulfide (WS2) Based Heterojunctions Photoanode Materials for High Performance Dye Sensitized Solar Cell Device (DSSCs) Applications

In this study, high order crystalline tungsten disulfide (WS2) nanoparticles/graphene sheets (WS2/Gs) were prepared via facile hydrothermal technique. Hexagonal crystalline structure of WS2 with individual spherical shaped nanoparticles within the average sizes of 35–40 nm were found through XRD, SEM and TEM analysis. Further the structure of the WS2/Gs was found with the presence of D and G bands along with WS2 based Raman modes in the Raman spectra analysis. The incorporated WS2 into Gs will significantly increasing the absorption property, tuning the band gap (2.87–2.21 eV) and rapid electron charge transfer process, which is identified through UV-DRS and PL analysis. The fabricated dye-sensitized solar cells device with WS2/graphene photo-electrode showed an open circuit voltage (Jsc) of 0.79 mV, short circuit current (Voc) of 18.6 mA cm−2, fill factor of 0.66, and power conversion efficiency of 9.6%. This could be due to the high surface area (98.45) and mesoporous nature (10.25 nm) of the WS2/Gs composite hybrid photo-anodes. The detailed mechanism of WS2 improved by Gs is also discussed in detail. The strategy could provide new ideas for obtaining novel hybrid photo-anodes with excellent photovoltaic performance.

The influence of MoSe2 coated onto Pt film to DSSC performance with the structure TiO2/Dye/LxMoSe2Pt (0 ≤ x ≤ 5)

Research on the influence of Molybdenum Diselenide (MoSe2) coating on platinum (Pt) to performing dye-sensitized solar cell (DSSC) with the structure of TiO2/Dye/LxMoSe2Pt, (0 ≤ x ≤ 5) is reported. The hydrothermal method has successfully synthesized the TiO2 film with square and porous morphology on the indium titanium oxide (ITO) surface. Four peaks of the Raman Scattering detected from the semiconductor confirm the formation of TiO2 film. The liquid-phase deposition (LPD) also successfully prepared the Pt film. Onto the prepared Pt, the MoSe2 was coated to produce LxMoSe2Pt (0 ≤ x ≤ 5) and then use them as the counter electrode (CE). The best DSSC devices with TiO2/Dye/L2MoSe2Pt structures have resulted in current–density, Voc, and solar cell performance of 11.204 mA/cm2, 0.66 V, and 2.967%, respectively. The Bode graph confirmed this device has the longest lifetime, proven by the highest peak rise in the lowest frequency. Besides, high-frequency also shows the device has low resistance, useful for accelerating the electrons flow and enhancing DSSC performance.

Electrospray preparation of CuInS2 films as efficient counter electrode for dye-sensitized solar cells

In this study, CuInS2 (CIS) thin films were prepared via electrospray (ES) method using a stable CIS nanoparticle dispersion with the assistance of thiourea additive. When the optimized CIS film was utilized as counter electrode (CE) for dye-sensitized solar cell (DSSC), a PCE of 8.81% was achieved under AM 1.5 illumination (100 mW cm−2), constituting over 13% improvement compared with platinum (Pt) control-device and being the highest among CIS based DSSCs. Further analyses show that the porous network in CIS film and the close contact between the FTO and the CIS film may account for the improvement because it not only offers more sites for efficient catalysis of redox couples in the electrolyte but also promotes charge transfer in the DSSC device. Moreover, the CIS film in the DSSC device was also proved to contribute to the photocurrent generation. This work firstly demonstrates the capability of ES method to fabricate CIS films and proves that the ES-prepared CIS film is a promising alternative to Pt CE in DSSC devices. Furthermore, this method can be adopted to prepare the CIS absorber in thin-film solar cells, as well as to prepare functional films based on other semiconductors.

Photovoltaic Performance of Porphyrin‐Based Dye‐Sensitized Solar Cells with Binary Ionic Liquid Electrolytes

Herein, green porphyrin sensitizer Y350‐based dye‐sensitized solar cells (DSCs) with binary ionic liquid–based electrolytes are studied, which are a mixture of 1‐methyl‐3‐propyl‐imidazolium iodide and 1‐methyl‐1‐butylpyrrolidinium bis(trifluromethylsulfonyl) ‐imide, 1‐butylpyridinium bis(trifluromethylsulfonyl)imide, 1‐methyl‐3‐ethylimidazolium bis(trifluromethylsulfonyl)imide, or 1‐methyl‐3‐ethylimidazolium tetracyanoborate. The best semitransparent green DSC device exhibits a short‐circuit photocurrent density of 9.1 mA cm−2, an open‐circuit photovoltage of 727 mV, and a fill factor of 70%, corresponding to an overall power conversion efficiency (PCE) of 4.9% under standard AM 1.5G illuminations at 100 mW cm−2. The PCE increases to 6.1% with opaque films containing larger light‐scattering TiO2 particles.

Areca catechu as photovoltaic sensitizer for dye-sensitized solar cell (DSSC)

Dye-Sensitized Solar Cell (DSSC) becomes more and more interesting since a huge variety of dyes included. The natural dyes can be used as light-harvesting elements which provide the charge carriers. This contribution research on the possibility of using natural dye Areca catechu from a local Malaysian Palm tree, namely Pinang fruit, extracted by using Acetonitrile as an extracted solvent for DSSC application. This study focuses on the properties of natural dye from Areca catechu, extracted with highly acidic media. Ultraviolet-visible absorption spectroscopy (UV-Vis), Fourier Transforms Infrared (FTIR), and Photoluminescence spectroscopy (PL) have been investigated for characterized dye. The natural dye extracted from Areca catechu has interesting properties due to the high degree of molecule conjugation. This dye is capable of absorbing light quantum, at low and high energies ranging from the infrared to the Ultraviolet (UV) region. The presence of natural dye in Areca catechu crust was reported by both UV-Vis and FTIR. While the intensity of Photoluminescence emissions reported a bandgap of 1.85 eV. Areca catechu as a natural dye for DSSC sensitization, promising to achieve high cell performance, low-cost production, and non-toxicity for future applications in dye-sensitized solar cell devices.

Imaging Dye Aggregation in MK-2, N3, N749, and SQ-2 dye···TiO2 Interfaces That Represent Dye-Sensitized Solar Cell Working Electrodes

Dye-sensitized solar cells (DSSCs) are a strong contender for next-generation photovoltaic technology with niche applications as solar-powered windows. The performance of a DSSC is particularly susceptible to the dye sensitizer, which is adsorbed onto the surface of a wide-band-gap semiconductor such as TiO2, to form the working electrode. The nature by which such surfaces are sensitized stands to influence the resulting dye···TiO2 interfacial structure and thence the operational performance of the DSSC working electrode. In particular, a nanoscopic understanding of the sensitization process would ultimately help to improve DSSC device function. In this study, atomic force microscopy (AFM) is used to image the nanoscopic formation of dye···TiO2 interfacial structures. This employs, as case studies, four well-known DSSC dyes adsorbed onto amorphous TiO2 substrates: two ruthenium-based dyes, N3 and the Black Dye (N749); and two organic dyes, the thiophenylcarbazole, MK-2, and the zwitterionic squaraine, SQ-2. We discover that all four dyes present some form of aggregation upon sensitization of TiO2, whose spatial distributions show distinct nanoaggregate particle characteristics. These particle clusters of N749, N3, and MK-2 are found to assemble in lines of nanoaggregates, while clusters of SQ-2 dye chromophores distribute themselves randomly on the amorphous TiO2 substrates. This nanoparticle structural assembly persists even when these dye···TiO2 interfaces are fabricated using hundred-fold diluted dye sensitization concentrations. The formation of dye aggregates in N749 is further studied as a function of dye sensitization time. This tracks the pattern formation of aggregates of N749 and reveals that dye aggregation begins within the first hour and has completed within a 5 h period. The large expanse of dye nanoaggregates observed shows that dye···dye interactions are much more important than previously envisaged, while the nature of their spatial distribution can be related to different aggregation modes of the dye molecules. These nanostructural features will undoubtedly impact the performance of DSSCs.

The Hagfeldt Donor and Use of Next-Generation Bulky Donor Designs in Dye-Sensitized Solar Cells.

"The Hagfeldt donor" is a bulky triarylamine building block with four alkyl chains in a 3-dimensional arrangement that is used with organic dyes in dye-sensitized solar cells (DSCs) in over 140 publications. Many of the highest performing DSC devices in literature make use of this group due to exceptional TiO2 surface protection properties, which slows recombination of electrons in TiO2 with the electrolyte. Importantly, record-setting cobalt and copper redox shuttle-based DSCs require exceptional surface protection to slow a facile recombination of electrons to these positively charged redox shuttles. Several syntheses have emerged for the Hagfeldt donor due to the need for iterative aryl-halide cross- coupling reactions complicating a straightforward route. Six synthetic strategies found in literature are described along with the challenges of each route. A recent method that has been put forward in the literature as a scalable, regioisomerically pure route is highlighted.

The Synchronization of Electron Enricher and Electron Extractor as Ternary Composite Photoanode for Enhancement of DSSC Performance

This work developed a novel ternary composite photoanode of dye-sensitized solar cell (DSSC) composed of (i) N-, S-doped titanium dioxide with exposed {001} facet (N-, S-TiO2{001}), (ii) N-, S-doped reduced graphene oxide (N-, S-rGO), and (iii) commercial titanium dioxide (P25). The DSSC device fabricated with the ternary composite photoanode showed the greatest of power conversion efficiency (8.62%) compared to the device fabricated with P25 photoanode (3.20%). This enhancement was attributed to the synergistic effect of the N-, S-TiO2{001} and the N-, S-rGO, which act as an electron enricher and an electron extractor, respectively.

Porous membrane of polyindole and polymeric ionic liquid incorporated PMMA for efficient quasi-solid state dye sensitized solar cell

Stable and efficient electrolyte for effective solar energy conversion is a persistent aim of dye-sensitized solar cell (DSSC). In this work, a novel honeycomb-like porous membrane (PMMA/PIL/PIN) based quasi-solid state (QSS) electrolyte was prepared by using the mixtures of synthesized polyindole (PIN),poly(3-decyl-1-vinyl imidazolium iodide) (PIL) and PMMA through non-solvent induced phase inversion method. The membranes were characterized in terms of their structure, morphology, physical properties (electrolyte uptake, porosity) and their photovoltaic and electrochemical effects as electrolyte in DSSC device were investigated. PMMA/PIL/PIN membrane was compared with PMMA/PIL, PMMA membrane and liquid electrolyte (LE) for their performance. The best QSS-DSSC with PMMA/PIL/PIN membrane exhibited high open circuit voltage (Voc), good short circuit current density (Jsc), comparable power conversion efficiency (η = 5.96 %) and superior stability (up to 84 % of its initial conversion efficiency after 250 h) compared to LE based DSSC. This innovative PMMA/PIL/PIN membrane based electrolyte pronounces the promising aspect for advancement in excellent performance of QSS-DSSC.

Synthesis and computational study of coumarin thiophene-based D-π-A azo bridge colorants for DSSC and NLOphoric application

This article is comprised of designing and synthesis of three coumarin-based donors (D)-π-azo-acceptor (A) colorants with −COOH and -SO3H anchoring groups for application in dye-sensitized solar cell (DSSC). Prototype DSSC devices were prepared with these colorants as sensitizers and were characterized through IV and EIS measurements to explore the practical performance. The well-performing colorant NAA 236 exhibit a short-circuit current density, Jsc of ∼10.28 mA cm−2, with an open-circuit voltage, Voc of ∼0.62 V. The electrochemical impedance spectroscopy (EIS) and electron lifetime (τe) analysis showed effective performance with Rrec (141.61 Ω) and τe10.5 ms for the NAA 236 colorant respectively. The power conversion efficiency (PCE) of 4.5 % (AM 1.5 G, 100 mW cm−2) is achieved for NAA 236 that has the −COOH (an anchoring group) at the para position of the azo group with fill factor FF of ∼ 68.7. Theoretical Density Functional Theory (DFT) and Time-Dependent TD-DFT calculations were performed using the method B3LYP/6-311+g(d,p). The HOMO-LUMO energy, vertical excitation energy, Global Reactivity Descriptors (GRD) i.e. electrophilicity index (ω), hyper-hardness(Γ) and Light-harvesting efficiency (LHE) property were assessed through optimized geometry, and it showed a linear trend with Power Conversion Efficiency (PCE). All the sensitizers demonstrate excellent non-linear optical (NLO) response and display a direct relation with photovoltaic performance.

Theoretical study of T shaped phenothiazine/carbazole based organic dyes with naphthalimide as π-spacer for DSSCs.

Eight novel T shaped phenothiazine/carbazole based organic dyes with naphthalimide as π-spacer were designed, and the geometries, electronic structures, and optical features of these isolated dyes and dye-(TiO2)9 systems were investigated with density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations. Some quantify factors influencing the energy conversion efficiency (PCE) such as the light harvesting efficiency (LHE), electron injection driving force (ΔGinject) and dye regeneration driving force (ΔGreg) were also calculated for dye-sensitized solar cells (DSSCs) applications. It is found that these dyes show a good performance of electron injection and dye regeneration owing to the proper value of ΔGinject and ΔGreg. The optimized geometries of the non-planar molecular configuration of donor and the planar structure of the naphthalimide conjugated bridge are beneficial to efficient intramolecular charge transfer and the suppression of molecular aggregation. The properties about the electronic structure and absorption spectra indicate that replacement of benzene with thiophene unit near to cyanoacetic acid acceptor can generate more efficient conjugation effect and achieve red shift of absorption spectra, resulting a higher Jsc and Voc in DSSCs device. The theoretical results reveal that DTPH2, DTPH4, DTCA2 and DTCA4 would be used as potential sensitizers for DSSCs applications.

Increasing the Efficiency of Dye-Sensitized Solar Cells by Adding Nickel Oxide Nanoparticles to Titanium Dioxide Working Electrodes

In this study, nickel oxide (NiO) nanoparticles were added to a titanium dioxide (TiO2) nanoparticle paste to fabricate a dye-sensitized solar cell (DSSC) working electrode by using a screen-printing method. The effects of the NiO proportion in the TiO2 paste on the TiO2 working electrode, DSSC devices, and electron transport characteristics were comprehensively investigated. The results showed that adding NiO nanoparticles to the TiO2 working electrode both inhibited electron transport (a negative effect) and prevented electron recombination with the electrolyte (a positive effect). The electron transit time was extended following an increase in the amount of NiO nanoparticles added, confirming that NiO inhibited electron transport. Furthermore, the energy level difference between TiO2 and NiO generated a potential barrier that prevented the recombination of the electrons in the TiO2 conduction band with the I3- ions in the electrolyte. When the TiO2–NiO ratio was 99:1, the positive effects outweighed the negative effects. Therefore, this ratio was the optimal TiO2–NiO ratio in the electrode for electron transport. The DSSCs with a TiO2–NiO (99:1) working electrode exhibited an optimal power conversion efficiency of 8.39%, which was higher than the DSSCs with a TiO2 working electrode.

Improved performance with molecular design of Ruthenium(II) complexes bearing diamine-based bidentate ligands as sensitizer for dye-sensitized solar cells (DSSC)

Herein, the derivatives of ruthenium (II) complexes bearing different diaminobenzene backbones were produced with the idea of molecular design and characterized. These complexes which are intended to be used as photoactive dyes in a DSSC device also contain suitable optoelectronic properties and the ligands capable of acting in accordance with the DSSC mechanism.The power conversion efficiencies (PCEs) of the first series synthesized ruthenium (II) complexes (5-8A) in DSSC tests were obtained in the range of 0.64–2.25%. Among these backbone structures, the superiority of the benzophenone structure, namely 8A, has been observed and its derivatives have been produced as a second series. The ruthenium (II) complexes produced as 8B and 8C were tested to see the effect of different functional groups on solar cell performances and although the power conversion efficiencies of these complexes were lower than the performance of 8A, they approached with 1.63% and 2.05% values. Thus, the effect of different functional and backbone group structures in the molecular structure on DSSC efficiencies was determined directly and it was emphasized that there could be significant increases in cell performances with the change of simple functional groups.

Fabrication and Electrochemical Behavior Investigation of a Pt-Loaded Reduced Graphene Oxide Composite (Pt@rGO) as a High-Performance Cathode for Dye-Sensitized Solar Cells

A platinum-reduced graphene oxide thin film composite (Pt@rGO, 100 nm) was prepared on a fluorine-doped tin oxide- (FTO-) coated glass substrate by a screen printing method using a Pt@rGO screen printing paste (0.12% Pt;Pt/rGO=1.5 w/w). The as-prepared electrode (denoted as Pt@rGO/FTO) was used as the cathode for the assembly of dye-sensitized solar cells (DSSCs). It showed a well-dispersed and high loading of Pt on rGO surface with a particle size distributed around 10 nm. The redox behavior of ferrocene was performed at Pt/FTO, Pt@rGO/FTO, and rGO/FTO electrodes by a cyclic voltammetry (CV) method. The kinetic parameters, in particular, the standard reduction potential (E0, V), the transfer coefficient (α), the heterogeneous rate constant (k0, cm·s-1), and the diffusion coefficient (D, cm2s-1), were determined by CV data treatment using convolution-deconvolution and fitting methods. The values ofE0,α,k0, andDat Pt@rGO/FTO electrode were, respectively, 326 mV, 0.471, 3.33 cm·s-1, and 4.19 cm2·s-1, equivalent to those of Pt/FTO electrode (340 mV, 0.474, 3.18 cm·s-1, and 4.19 cm2·s-1). The Pt@rGO/FTO electrode exhibited excellent electrocatalytic activity compared to that of Pt thin film (Pt/FTO electrode) prepared from Pt commercial paste. The heterogeneous electron transfer rate constantk0(cm·s-1) for I3-/I-at Pt@rGO/FTO is 1.3 times faster than that at Pt/FTO. The energy conversion efficiency of the DSSCs assembled from Pt@rGO-DSSC cathode reached 7.0%, an increase of 20.7% over the commercial Pt-based cathode (Pt-DSSC, 5.8%). The rGO component in the Pt@rGO composite plays two important roles: (i) facilitating the electron transfer between Pt NPs catalyst and the FTO substrate via the bandgap effect and (ii) the enlargement catalytic surface area of Pt NPs via the loading effect. The rGO material has, therefore, potential to replace the Pt content and improve the performance of the DSSC device.

Synthesis and characterization of novel tetra anchoring A2-D-D-D-A2 architecture sensitizers for efficient dye-sensitized solar cells

Novel metal free organic dyes coded TET(RA)4, TET(CA)4, and TET(QA)4 were designed, synthesized, and characterized as effective sensitizers for dye sensitized solar cells (DSSCs). These new push-pull sensitizers used a strong electron donor consisting of 3,4-ethylenedioxythiophene and two triphenylamine molecules connected together to form a TPA-EDOT-TPA (TET) motif, which is directly connected to tetra anchoring groups (A) without any π-spacers to construct A2-D-D-D-A2 architecture, three different anchoring series, viz. rhodanine-3-acetic acid (RA), cyanoacetic acid (CA), and 2-methyl quinoline-6-carboxylic acid (QA) were employed to investigate the influence of anchoring moieties on the electrochemical, thermodynamic, kinetics, and photovoltaic efficiency of DSSCs. The DSSCs devices showed a maximum overall power conversion efficiency (PCE) = 5.13%, short-circuit current density (JSC) = 12.71 mA.cm−2, open circuit voltage (VOC) = 0.62 V, and fill factor (FF) = 65.36% with a maximum incident photon conversion efficiency (IPCE) = 75% for TET(QA)4. The optical and electrochemical studies showed that TET(QC)4 achieved higher electron injection free energy (ΔG°inj) into CB edge of TiO2 as well as high recombination resistance (Rrec) compared to TET(RA)4, and TET(CA)4, which explains the outstanding charge separation and superior power conversion efficiency (PCE) of TET(QC)4 possessing quinoline-6-carboxylic acid (QC) anchoring group. Molecular modeling calculations using DFT and TD-DFT showed effective charge separation, where HOMO is delocalized over the donor scaffold (TPA-EDOT-TPA), and the LUMO is delocalized over only two anchoring groups on the same side of the donor system, which provides strong HOMO-LUMO overlap as well as intimate electronic coupling with TiO2 nanoparticle surface for electron injection. Further, the calculated values of the energy gaps (E0-0) and ground/excited stated oxidation potentials were in perfect agreement with the experimental results.

Balance of catalytic activity and conductivity of Cu2ZnSnS4/graphene counter electrode for dye-sensitized solar cells: using hydrothermal-synthesized kesterite Cu2ZnSnS4 and graphene obtained by product line

The catalytic activity and conductivity of Cu2ZnSnS4/graphene counter electrode for dye-sensitized solar cells (DSSCs) was balanced using hydrothermal-synthesized kesterite Cu2ZnSnS4 and graphene obtained by product line. It was found that the electrocatalytic activity of Cu2ZnSnS4/graphene counter electrode was adjustable by balancing its catalytic activity and conductivity using varied weight ratio of graphene in the composited material of Cu2ZnSnS4/graphene. When the weight percent of graphene was 2% to Cu2ZnSnS4, the catalytic activity and conductivity of Cu2ZnSnS4/graphene counter electrode came to the balanced point, resulting in the best electrocatalytic activity. Under the balanced conditions, the dye-sensitized solar cell devices based on Cu2ZnSnS4/graphene counter electrode show a maximum solar-to-electrical power efficiency of 3.71% (with short-circuit photocurrent density Jsc of 13.24 mA cm−2, open-circuit photovoltage Voc of 0.63 V, and fill factor FF of 0.44), which is higher than that of unbalanced counter electrode. Although the photovoltaic performance of DSSCs based on Cu2ZnSnS4/graphene counter electrode was a little lower than that of DSSCs based on platinum (Pt) counter electrode (4.95%), it is believed that Cu2ZnSnS4/graphene counter electrode would outperform Pt counter electrode by further balancing its catalytic activity and conductivity using higher-quality and more matched Cu2ZnSnS4 and graphene. This strategy to improve the electrocatalytic activity of counter electrode will be helpful for exploring facile synthesis, low-cost, and efficient Cu2ZnSnS4-based composited counter electrode materials.

Quantum dot embedded N-doped functionalized multiwall carbon nanotubes boost the short-circuit current of Ru(ii) based dye-sensitized solar cells.

Here, we report zinc sulfide quantum dots, ZnS(QDs), moored on N-doped functionalized multiwall carbon nanotubes (MWCNTs) wrapped with reduced graphene oxide (rGO). The MWCNTs have a tangled network, a particular surface area, and a distinctive hollow structure that may be suitable for use as a counter electrode (CE) material. A ZnS@N.f-MWCNTs@rGO composite as the CE on a fluorine-doped tin oxide substrate in a dye-sensitized solar cell (DSSC) was fabricated using a doctor blade technique. The electrochemical performance showed that at the electrolyte/CE interface, the ZnS(QDs) and N-doped functionalized MWCNTs wrapped with rGO (ZnS@N.f-MWCNTs@rGO) electrode has a lower transfer charge resistance (Rct) and a greater catalytic capacity than naked ZnS(QDs). A power conversion efficiency (PCE) of 9.4% was attained for this DSSC gadget, which is higher than that of a DSSC gadget utilizing ZnS(QDs), ZnS@N.f-MWCNTs, ZnS@rGO and Pt. Also, the DSSC device using ZnS@N.f-MWCNTs@rGO had a fill factor (FF) that was better than the other counter electrodes. The cyclic voltammetry and electrochemical impedance spectra (EIS) electron transfer measurements showed that ZnS@N.f-MWCNTs@rGO films can provide fast electron transfer from the electrolyte to the CE and great electrocatalytic activity to reduce triiodide to a CE based on ZnS@N.f-MWCNTs@rGO in the DSSC.

Synthesis and Characterization of TiO2 thin film Electrode based Dye Sensitized Solar Cell

Dye-Sensitized Solar Cells (DSSCs) are prominent alternative devices to conventional p-n junction silicon based solar cells because of their low fabrication cost and high power conversion efficiency, good cost/efficiency ratio. In the present work, DSSC devices were made-up with fluorine doped tin oxide (FTO) glass substrate, a TiO2 compact layer was deposited on FTO, Ruthenium(II) dye (N719), an iodide - triiodide electrolyte and a platinum (Pt) counter electrode. Photo anode with thin film layers of TiO2 and Pt counter electrode (photo-cathode) were prepared. Field emission electron microscope (FESEM) was employed to investigate the surface morphology of TiO2 layers. The DSSC device efficiency was evaluated by J-V characteristics. Fabricated devices were exhibited high power conversion efficiencies. The electrochemical impedance characteristics were analyzed by fitting the experimental results to the corresponding electrical equivalent circuit simulated data.

Optimizing Photovoltaic Efficiency of a Dye-Sensitized Solar Cell (DSSC) by a Combined (Modelling-Simulation and Experimental) Study

A comparative investigation involving experimental and modelling-simulation is carried out to maximize the photovoltaic conversion efficiency (I·) of a DSSC device assembled using N719 dye, an iodide redox liquid electrolyte and TiO 2 electrode. The measured current density-voltage (J-V) characteristics under 1 sun condition of a pre-assembled DSSC is simulated in a tiberCAD based microscopic model (TCMM) along with single-diode based macroscopic model (SDMM). The calibrated model parameters are then utilized for predicting a maximum I· of a DSSC belonging to an unknown electrode’s thickness (L). The microscopic simulations provided a good qualitative nature of J V characteristics curves for different L and I· values. A complete and best J-V curve fitting is achieved using a TCMM by incorporating an unaccounted series resistance of a FTO substrate. Particularly, model simulated J-V characteristics matches perfectly well to experimental results of a post-assembled DSSC device (I·~5.46 %; L~12.0 µm) with a tolerable error (<0.1%).

Copper-based redox shuttles supported by preorganized tetradentate ligands for dye-sensitized solar cells.

Three copper redox shuttles ([Cu(1)]2+/1+, [Cu(2)]2+/1+, and [Cu(3)]2+/1+) featuring tetradentate ligands were synthesized and evaluated computationally, electrochemically, and in dye-sensitized solar cell (DSC) devices using a benchmark organic dye, Y123. Neutral polyaromatic ligands with limited flexibility were targeted as a strategy to improve solar-to-electrical energy conversion by reducing voltage losses associated with redox shuttle electron transfer events. Inner-sphere electron transfer reorganization energies (λ) were computed quantum chemically and compared to the commonly used [Co(bpy)3]3+/2+ redox shuttle which has a reported λ value of 0.61 eV. The geometrically constrained biphenyl-based Cu redox shuttles investigated here have lower reorganization energies (0.34-0.53 eV) and thus can potentially operate with lower driving forces for dye regeneration (ΔGreg) in DSC devices when compared to [Co(bpy)3]3+/2+-based devices. The rigid tetradentate ligand design promotes more efficient electron transfer reactions leading to an improved JSC (14.1 mA cm-2), higher stability due to the chelate effect, and a decrease in VlossOC for one of the copper redox shuttle-based devices.