Dye-sensitized Solar Cell Architecture Research Articles

Advancements in Carbazole-Based Sensitizers and Hole-Transport Materials for Enhanced Photovoltaic Performance.

Carbazole-based molecules play a significant role in dye-sensitized solar cells (DSSCs) due to their advantageous properties. Carbazole derivatives are known for their thermal stability, high hole-transport capability, electron-rich (p-type) characteristics, elevated photoconductivity, excellent chemical stability, and commercial availability. This review focuses on DSSCs, including their structures, working principles, device characterization, and the photovoltaic performance of carbazole-based derivatives. Specifically, it covers compounds such as 2,7-carbazole and indolo[3,2-b]carbazole, which are combined with various acceptors like benzothiadiazole, thiazolothiazole, diketopyrrolopyrrole, and quinoxaline, as reported over the past decade. The review will also outline the relationship between molecular structure and power-conversion efficiencies. Its goal is to summarize recent research and advancements in carbazole-based dyes featuring a D-π-A architecture for DSSCs. Additionally, this review addresses the evolution of carbazole-based hole-transport materials (HTMs), which present a promising alternative to the costly spiro-OMeTAD. We explore the development of novel HTMs that leverage the unique properties of carbazole derivatives to enhance charge transport, stability, and overall device performance. By examining recent innovations and emerging trends in carbazole-based HTMs, we provide insights into their potential to reduce costs and improve the efficiency of DSSCs.

A New Type of Architecture of Dye-Sensitized Solar Cells as an Alternative Pathway to Outdoor Photovoltaics

The current investigation shows a possible new pathway for more efficient and cost-effective energy-harvesting photovoltaic devices. Our approach could permit all emerging technologies that are currently used for indoors and smart buildings to go a step forward and could be used for outdoor applications. The investigated architecture is a very promising geometry especially for Dye-Sensitized Solar Cells (DSSCs). It turns their main drawback, the lowering of their efficiency and lifetime when operating at high solar irradiation density, into an asset by increasing the total active area per horizontal unit area for light harvesting, while preserving the active elements from degradation and extending durable lifetime. The investigated architecture is based on a symmetric “U” type geometry, which is constructed by a highly reflective material on the inner surface. Solar irradiation is reflected internally at the bottom of the construction and splits towards two opposite sided solar cells; the two cells form a cavity where the solar light multiplies and is successively absorbed. Consequently, the vertically incoming irradiation is reduced when reaching the vertical internal sides on which the DSSCs are mounted. Thus, the solar cells operate at low light intensities, which provide significant lifetime extension and efficiency enhancement. Interestingly, the electrical energy per effective surface unit, which is produced by the two vertical DSSCs, is at least equal to that of a standalone, vertically irradiated cell. The advantage of the new architecture is that protects DSSCs from their degradation and deterioration, although the entire system operates under high illumination. This makes the cells more efficient outdoors, with a comparable performance to indoor conditions.

Electrochemically stable, cost-effective and facile produced selenium@activated carbon composite counter electrodes for dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs), as third generation photovoltaic technology, have been extensively investigated due to their numerous advantages, such as inexpensive and simple/fast preparation methods. As known, DSSCs are composed of different components. Counter electrode, which is one of the components, is an indispensable part of high-performance DSSCs. Designing new counter electrodes (CEs) with low cost and desired physical and electrochemical properties are important to achieve higher performance/stable DSSCs. In this sense, in this current report, new selenium@activated carbon (Se@AC) composites as alternative to expensive platinum (Pt) were produced by cost-effective and facile applied ball milling method, and used as CE in the DSSC architecture. Here, firstly, porous activated carbon (AC) was prepared from fruit peel wastes via chemical activation technique. Then the Se was incorporated into the structure of porous AC with different ratios to improve different physical and electrochemical properties of pristine AC. After Se incorporation strategy, the electro-catalytic activity and charge transfer parameters (RCT value decreased from 27.41 to 12.09 Ω cm2) of Se@AC composite CEs were significantly enhanced. The fabricated DSSC with a CE using Se@AC:3@5 showed a power conversion efficiency (PCE) value of 5.67% with current density (Jsc) of 13.26 mA/cm2, open-circuit voltage (Voc) of 648 mV and fill factor (FF) of 66%, which can acceptable close to the performance of the fabricated DSSC with the Pt-based CE (6.86%). The improvement electro-catalytic activity and charge transfer properties obtained with the low cost and facile production process could render the Se@AC composite CE standing out as an effective alternative to the precious/expensive Pt reference CE.

Donor-free oligothiophene based dyes with di-anchor architecture for dye-sensitized solar cells

We report the synthesis and DSSCs of oligothiophenes with two anchoring groups that can adopt V- and U-shape conformations.

Focus-Induced Photoresponse Technique-Based NIR Photodetectors Containing Dimeric Polymethine Dyes

A group of near infrared (NIR)-absorbing dimeric polymethine dyes have been developed and successfully applied in photodetectors based on focus-induced photoresponse technology. The devices are based upon simple and inexpensive solid-state dye-sensitized solar cell architecture. The investigated molecules, designed and synthesized specifically for focus-induced photoresponse application, demonstrate relatively narrow and intense absorption in the NIR region of the spectrum up to 900 nm. Detectors containing the investigated dyes function in the near-infrared region of the spectrum, and suitable photocurrent and signal-to-noise ratio can be obtained at both 730 nm and 850 nm wavelengths. Additionally, these photodetectors can also be used in applications requiring simultaneous tracking of multiple light spots, as devices maintain appropriate characteristics at light modulation frequencies between 1 Hz and 1000 Hz.

Cs2SnI6-Encapsulated Multidye-Sensitized All-Solid-State Solar Cells.

The design of a dye-sensitized solar cell (DSSC) based on the simultaneous incorporation of multiple dyes is examined. By investigating the use of the porphyrin-based YD2-o-C8 and YDD6, and the organic chromophore TTAR, which can act as complementary absorbers, we are able to enhance the capture of incoming light across the solar spectrum. This is demonstrated first by using a conventional DSSC architecture with a liquid electrolyte and performed a power conversion efficiency (PCE) of 11.2%, representing an improvement over cells based on each of the independent dyes. Next, we used Cs2SnI6 as an encapsulating layer over the sensitizing molecules to reduce charge leakage across the dye layers and also added to the absorption of longer wavelengths up to one micron. Finally, we fabricated a cell utilizing a Cs2SnI6/succinonitrile solid hole-transport electrolyte and achieved a PCE of ∼8.5%. It is expected that the all solid-state design will go a long way toward improving long-term device stability.

Direct Contact of Selective Charge Extraction Layers Enables High-Efficiency Molecular Photovoltaics

Summary Dye-sensitized solar cells (DSCs) are molecular photovoltaics that operate efficiently in direct solar and ambient light by employing dye-impregnated mesoscopic TiO 2 films with a redox electrolyte or hole conductor. Here, we report on an advanced DSC architecture, which achieves efficiencies of 13.1% under air mass 1.5 global, 100 mW cm −2 solar radiation, and power conversion efficiency of 32% under a standard Osram 930 Warm White fluorescent tube light at 1,000 lux intensity. The cell substantially benefits from the direct contact of the dye-impregnated TiO 2 film with the poly(3,4-ethylenedioxythiophene) (PEDOT) counter electrode acting as a hole collector. This reduces the diffusion path of redox mediator to merely the mesoporous TiO 2 film attenuating the Warburg resistance, which thereby boosts the photovoltaic performance. This architecture will not only accelerate the practical exploitation of DSCs, but also foster new types of light-harvesting devices using mesoscopic TiO 2 and PEDOT as electron and hole collection layers, respectively.

Molecular Engineering of a New Organic Chromophore with D-π-A Architecture for Dye-Sensitized Solar Cells

Herein, we report design and synthesis of a new metal-free organic dye N1 derived from (Z)-3-(9-hexyl-9H-carbazol-3-yl)-2-(thiophen-2-yl) acrylonitrile scaffold. In this design, the electron rich carbazole unit is connected to rhodanine-3-acetic acid via cyano vinyl thiophene as π-spacer. Its molecular structure was confirmed by FTIR, NMR, Mass spectral and elemental analyses. The dye was subjected to optical and electrochemical studies in order to investigate their absorption/emission behaviour as well as HOMO/LUMO energies. The DFT studies were performed using Turbomole 7.1V software and the results indicated the existence of proper charge separation between its HOMO and LUMO energy levels.

Solvothermal Synthesis of Hierarchical TiO2 Microstructures with High Crystallinity and Superior Light Scattering for High-Performance Dye-Sensitized Solar Cells.

In this article, hierarchical TiO2 microstructures (HM-TiO2) were synthesized by a simple solvothermal method adopting tetra-n-butyl titanate as the titanium source in a mixed solvent composed of N,N-dimethylformamide and acetic acid. Due to the high crystallinity and superior light-scattering ability, the resultant HM-TiO2 are advantageous as photoanodes for dye-sensitized solar cells. When assembled to the entire photovoltaic device with C101 dye as a sensitizer, the pure HM-TiO2-based solar cells showed an ultrahigh photovoltage up to 0.853 V. Finally, by employing the as-obtained HM-TiO2 as the scattering layer and optimizing the architecture of dye-sensitized solar cells, both higher photovoltage and incident photon-to-electron conversion efficiency value were harvested with respect to TiO2 nanoparticles-based dye-sensitized solar cells, resulting in a high power conversion efficiency of 9.79%. This work provides a promising strategy to develop photoanode materials with outstanding photoelectric conversion performance.

Dual Functional Polymer Interlayer for Facilitating Ion Transport and Reducing Charge Recombination in Dye-Sensitized Solar Cells.

Dye-sensitized solar cells (DSSCs) present low-cost alternatives to conventional wafer-based inorganic solar cells and have remarkable power conversion efficiency. To further enhance performance, we propose a new DSSC architecture with a novel dual-functional polymer interlayer that prevents charge recombination and facilitates ionic conduction, as well as maintaining dye loading and regeneration. Poly(vinylidene fluoride-trifluoroethylene) (p(VDF-TrFE)) was coated on the outside of a dye-sensitized TiO2 photoanode by a simple solution process that did not sacrifice the amount of adsorbed dye molecules in the DSSC device. Light-intensity-modulated photocurrent and photovoltage spectroscopy revealed that the proposed p(VDF-TrFE)-coated anode yielded longer electron lifetime and improved the injection of photogenerated electrons into TiO2, thereby reducing the electron transport time. Comparative cyclic voltammetry and UV-visible absorption spectroscopy based on a ferrocene-ferrocenium external standard material demonstrated that p(VDF-TrFE) enhanced the power conversion efficiency from 7.67% to 9.11%. This dual functional p(VDF-TrFE) interlayer is a promising candidate for improving the performance of DSSCs and can also be employed in other electrochemical devices.

Floating Photovoltaics: Floating, Flexible Polymeric Dye‐Sensitized Solar‐Cell Architecture: The Way of Near‐Future Photovoltaics (Adv. Mater. Technol. 2/2016)

Floating Photovoltaics: Floating, Flexible Polymeric Dye‐Sensitized Solar‐Cell Architecture: The Way of Near‐Future Photovoltaics (Adv. Mater. Technol. 2/2016)

A facile low temperature route to deposit a TiO2 scattering layer for efficient dye-sensitized solar cells

Hydrolysis of TiCl4 at low temperature formed an efficient scattering layer in dye-sensitized solar cell architecture, which leads to an improvement in the light harvesting and a remarkable reduction of electronic disorder of mesoporous-TiO2.

A novel triple-layer zinc oxide/carbon nanotube architecture for dye-sensitized solar cells with excellent power conversion efficiency

A novel triple-layer photoanode architecture, composed of ZnO and ZnO/CNT nanostructure semiconductor films for dye-sensitized solar cell with excellent power conversion efficiency is fabricated by a simple strategy. A convenient and effective method is applied to disperse the multiwalled carbon nanotube (MWCNT). The structure, morphology and light absorption of the novel hybrid photoanode are characterized by X-ray diffraction, scanning electron microscopy, and UV–vis absorption spectroscopy analyze. Results indicate that the ZnO has a typical wurtzite structure and the MWCNTs are homogeneously dispersed in ZnO. Current–voltage curves demonstrate CNT-0.5 with 0.05wt% of carbon nanotube (CNT) is the most suitable in improving the performance of DSSCs, and the power conversion efficiency of ZnO/CNT-0.5–0.05wt% is 6.25%, which is 35.57% higher than those without CNTs (4.61%). Finally, electrochemical impedance spectra confirms that the abundant dyes absorption by the ZnO layer and large numbers of direct pathway for electron transport provided by the MWCNTs are attributed to the high efficiency of this new DSSC. This result is remarkable and provides a novel triple-layer ZnO/CNT architecture in improving the performance of DSSCs.

Novel dye-sensitized solar cell architecture using TiO2-coated Ag nanowires array as photoanode

With the aim of reducing series resistance and increasing dye loading, novel dye-sensitized solar cell architecture was designed with TiO2 nanoparticle-coated Ag nanowires array as the photoanode. Ag nanowire array was prepared by anodic aluminum oxide (AAO) template-assisted electrochemical deposition route. Then, Ag nanowires were coated by TiO2 nanoparticles in hydrothermal process. The structures of the photoanode were characterized by field emission scanning electron microscopy (FESEM). Ag nanowires are covered by a layer of very fine nanoparticles with a diameter of less than 5 nm. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) show that Ag nanowires have a strong preferred orientation in (220) direction and the TiO2 coating layer is a polycrystalline structure. With this photoanode, 3.2 % conversion efficiency is achieved for the cell sensitized with N3 dye.

Functionally Engineered Egg Albumen Gel for Quasi-Solid Dye Sensitized Solar Cells

In this report, we demonstrated an interesting application of a bioderived material for the dye sensitized solar cells (DSSCs). Egg white, the clear liquid in a hen’s egg, which possesses a remarkable gelling/cross-linking ability, was applied in the form of a gel electrolyte in a DSSC architecture to enhance its durability. A hybrid gel composed of poly(acrylic acid), polyaniline and egg albumen was synthesized, and the cell efficiency, stability and durability of the corresponding DSSC device were studied in detail. The dye sensitized solar cell with the egg albumen based electrolyte demonstrated a conversion energy efficiency of 4.6%. Further, a chemically modified egg albumen with ethylenediaminetetraacetic dianhydride showed improved cross-linking, microstructural and conductivity properties of the gel, and yielded a remarkable 5.75% conversion efficiency. Electrochemical impedance spectroscopy data showed favorable characteristics for charge transport through the modified gel and supported the efficiency observations very well.

New organic dyes based on a dibenzofulvene bridge for highly efficient dye-sensitized solar cells

We demonstrate that carbon-bridged dibenzofulvene (DBF)-linked dyes serve as a novel and efficient structural architecture for dye-sensitized solar cells (DSSC)s.

Modeling opto-electronic properties of a dye molecule in proximity of a semiconductor nanoparticle

A general methodology is presented to model the opto-electronic properties of a dye molecule in the presence of a semiconductor nanoparticle (NP), a model system for the architecture of dye-sensitized solar cells. The method is applied to the L0 organic dye solvated with acetonitrile in the neighborhood of a TiO2 NP. The total reaction potential due to the polarization of the solvent and the metal oxide is calculated by extending the polarizable continuum model integral equation formalism. The ground state energy is computed by using density functional theory (DFT) while the vertical electronic excitations are obtained by time-dependent DFT in a state-specific corrected linear response scheme. We calculate the excited state oxidation potential (ESOP) for the protonated and deprotonated forms of the L0 dye at different distances and configurations with respect to the NP surface. The stronger renormalizations of the ESOP values due to the presence of the TiO2 nanostructure are found for the protonated dye, reaching a maximum of about -0.15 eV. The role of protonation effect is discussed in terms of the atomic Löwdin charges of the oxidized and reduced species. On the other hand, we observed a weak effect on the L0 optical excitation gap due to the polarization response of the NP.

Density functional theory characterization and verification of high-performance indoline dyes with D–A–π–A architecture for dye-sensitized solar cells

Abstract Six indoline-based dyes 1 – 6 used in DSSCs with difference in π spacer were theoretically researched and verified using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to shed light on how the additional (auxiliary) acceptor and π spacer order influence the performance of the dye. Key parameters associate with the short-circuit current density ( J sc ) and open-circuit photovoltage ( V oc ), including light-harvesting efficiency LHE , electron injection driving force Δ G inject , total reorganization energy λ total ( λ h and λ e ), the vertical dipole moment μ normal , the energy differences eV oc between E LUMO and E CB as well as the extent of electron recombination were characterized. The theoretical results reveal that compared with dye 1 , dyes 2 – 6 improve the performance potentially due to their auxiliary acceptor. These enable us to determine these factors related to the J sc and V oc can be significantly influenced by the incorporated electron-withdrawing subunit into molecular backbone.

Zirconium(IV) and Hafnium(IV) Porphyrin and Phthalocyanine Complexes as New Dyes for Solar Cell Devices

Metalloporphyrin and metallophthalocyanine dyes ligating Hf(IV) and Zr(IV) ions bind to semiconductor oxide surfaces such as TiO(2) via the protruding group IV metal ions. The use of oxophylic metal ions with large ionic radii that protrude from the macrocycle is a unique mode of attaching chromophores to oxide surfaces in the design of dye-sensitized solar cells (DSSCs). Our previous report on the structure and physical properties of ternary complexes wherein the Hf(IV) and Zr(IV) ions are ligated to both a porphyrinoid and to a defect site on a polyoxometalate (POM) represents a model for this new way of binding dyes to oxide surfaces. The Zr(IV) and Hf(IV) complexes of 5,10,15,20-tetraphenylporphyrin (TPP) with two ligated acetates, (TPP)Hf(OAc)(2) and (TPP)Zr(OAc)(2), and the corresponding metallophthalocyanine (Pc) diacetate complexes, (Pc)Hf(OAc)(2) and (Pc)Zr(OAc)(2), were evaluated as novel dyes for the fabrication of dye-sensitized solar cells. Similarly to the ternary complexes with the POM, the oxide surface replaces the acetates to affect binding. In DSSCs the Zr(IV) phthalocyanine dye performs better than the Zr(IV) porphyrin dye, and reaches an overall efficiency of ~ 1.0%. The Hf(IV) dyes are less efficient. The photophysical properties of these complexes in solution suggested energetically favorable injection of electrons into the conduction band of TiO(2) semiconductor nanoparticles, as well as a good band gap match with I(3) (-)/I(-) pair in liquid 1-butyl-3-methyl imidazolium iodide. The combination of blue absorbing TPP with the red absorbing Pc complexes can increase the absorbance of solar light in the device; however, the overall conversion efficiency of DSSCs using TiO(2) nanoparticles treated with a mixture of both Zr(IV) complexes is comparable, but not greater than, the single (Pc)Zr. Thus, surface bound (TPP)Zr increases the absorbance in blue region of the spectra, but at the cost of diminished absorbance in the red in this DSSC architecture.

Aggregation-free branch-type organic dye with a twisted molecular architecture for dye-sensitized solar cells

A new aggregation-free branch-type organic dye for dye-sensitized solar cells (DSCs) is developed by means of a twisting π-conjugation strategy. In comparison with the analogue planar dye, the twisting dye shows excellent potential as a new aggregation-free organic dye for DSCs.