Development Of Dye-sensitized Solar Cells Research Articles

Dye-Sensitized Solar Cells Characterization of Kitolod Leaves (Hippobroma longifora)

Energy from fossil fuels is decreasing day by day and also causes many environmental problems. In the current era, many environmentally friendly renewable energy sources have been developed, such as the development of DSSC (Dye Sensitized Solar Cells). DSSC is a technology that utilizes colored materials sourced from nature which are used as absorbers of sunlight energy to be converted into electrical energy. In this research, the synthesis and characterization of organic material from kitolod leaves as DSSC will be carried out. Kitolod leaves (Hippobroma longifora) are wild plants that usually grow in home gardens and rice fields. Kitolod leaves which have chlorophyll can support the absorption of sunlight if applied as a sensitizer in DSSC. The methods that will be used in this research are making TiO2 paste, dye solution preparation, electrolyte solution preparation, DSSC fabrication, testing and characterization. The tests that will be carried out are testing the TiO2 layer, dye absorption, and electric current. Meanwhile, the characterization that will be carried out is dye absorption using UV-Vis, and electric current using a potentiometer. From the results of light absorption shows that when the wavelength is 500 nm or the green light spectrum, the maximum light absorption by the chlorophyll of kitolod leaves is 1.78 (a.u.). The maximum voltage (Vm) and maximum current (Im) in daylight lamps have greater values ​​compared to warm white lamps. The highest efficiency of the solar light source is shown when the air mass is 1.5 (08.30-08.40). The time of DSSC immersion in dye also influences the resulting of Vm and Im values ​​which can be shown in that the Vm and Im values ​​of DSSC 2 (30 minutes) are greater than those of DSSC 1 (10 minutes). The results of open circuit voltage (Voc) and the short circuit current (Isc) in this research still need to be improved to produce better efficiency.

Introduction of methoxy and trifluoromethyl groups into zinc porphyrin sensitizers applications in self-assembled dye-sensitized solar cells

In this study, we have successfully constructed two novel self-assembled composites, the ZnPx-ZnPAc (x = 1,2), which based on zinc porphyrin derivatives, and applied them to the development of dye-sensitized solar cells. The upper dye of these self-assembly’s features zinc porphyrin (ZnPx) as the core unit, while two different electron donors, methoxy (P1) and trifluoromethyl (P2), are introduced to enhance their photovoltaic properties. Photoelectrochemical studies showed that the power conversion efficiency of ZnP1-ZnPAc was superior to that of ZnP2-ZnPAc because ZnP1-ZnPAc had larger Jsc and Voc, which could be attributed to the stronger electron-donating ability of methoxy than trifluoromethyl. To further validate the photoelectrochemical results, we also characterized the assembly mode by spectroscopy, theoretical calculations and electrochemical impedance spectroscopy. And the measurements were consistent with the conclusions.

Unveiling the potential of TPA-based molecules to tune the optoelectronic properties and enhance the efficiency of dye-sensitized solar cells.

The world's energy and environmental requirements are changing due to rapid population growth and industrial growth, and solar cells can be used to meet these demands. Dye-sensitized solar cells (DSSCs) are solar cells in which energy conversion occurs via a process similar to photosynthesis in plants. DSSC development is still in its infancy. DSSCs can operate under cloudy conditions and indirect sunlight and have attracted considerable attention due to their low cost and high efficiency. We designed two metal-free TPA-based dyes (Dye2 and Dye3) based on the reference dye Mg207 (Dye1) by increasing the donor strength of the molecule, as such dyes have shown enhanced efficiency in DSSCs. Moreover, the triphenylamine (TPA) moiety has been demonstrated to be a good donor that prevents charge recombination. Intramolecular charge transfer (ICT) from the donor to acceptor moiety was found in the sensitizers, and electrons were promoted to the conduction band (CB) of the TiO2 semiconductor. The negative binding energy of the dye@TiO2 clusters indicated that dye adsorption on the semiconductor surface was stable. The double donor increased the electron injection and electronic coupling constants in Dye2 and Dye3, indicating that these newly designed dyes have superior charge injection capacity. Accordingly, the efficiencies of DSSCs with Dye2 and Dye3 were 9.77% and 9.62%, respectively, and substitution with the TPA unit at the -R1 and -R2 positions in Dye1 resulted in better power conversion compared to the parent compound (9.09%). Increased donor strength improved photovoltaic performance by increasing current density and light-harvesting efficiency. This is a good molecular design approach for preparing targeted donor- -acceptor (D- -A) organic dyes with high DSSC efficiency. To predict the charge transport and optoelectronic characteristics of the TPA dyes, quantum chemical calculations were carried out using Gaussian16. The ground-state (S0) optimized geometries of the sensitizers were computed by utilizing DFT at the B3LYP/6-31G** level. The absorption spectra ( max) were computed by employing TD-DFT with various functionals (B3LYP, PBE1PBE, CAM-B3LYP, and BHandHLYP) in the gas and solvent (DCM) phases. Among the studied functionals, BHandHLYP was found to be best at successfully reproducing the experimental data. Thus, the absorption spectra of the newly designed dyes and dye@TiO2 were calculated at the BHandHLYP/6-31G** level. The dye@TiO2 cluster optimizations were carried out at the B3LYP/6-31G**(LANL2DZ) level.

Characterization and Application of Natural Photosensitizer and Poly(vinylidene Fluoride) Nanofiber Membranes-Based Electrolytes in DSSC

This comprehensive research has explored the potential of enhancing dye-sensitized solar cells (DSSC) by harnessing environmentally friendly natural dyes, such as chlorophyll pigments from pandanus (664.1 nm) and papaya leaves (664.0 nm), as well as betacyanin pigments from sappan-mangosteen (536.2 nm). Electrochemical analyses elucidated the energy band gaps, revealing a hierarchy with the smallest band gap observed for papaya leaves (1.387 eV), followed closely by sappan-mangosteen (1.389 eV) and pandan leaves (1.396 eV). This research effectively addressed the persistent issue of electrolyte leakage in DSSC development by introducing a polymer electrolyte derived from polyvinylidene fluoride (PVDF) through electrospinning and phase inversion techniques. SEM characterization results and thermogravimetric analysis underscored the superior characteristics and high thermal stability of the PVDF nanofiber polymer for DSSC applications. The study's pivotal findings underscore the remarkable DSSC performance achieved with chlorophyll pigment from papaya leaves, reaching 1.31% efficiency without a polymer electrolyte. Moreover, the sappan-mangosteen dye emerged as a promising contender with the highest efficiency values when applied with polymer electrolyte, recording rates of 1.17% for PVDF NF and 0.95% for PVDF, which are notably comparable to the efficiency of liquid electrolyte at 1.26%.

Development of dye-sensitized solar cells using pigment extracts produced by Talaromyces atroroseus GH2

The identification of more efficient, clean, secure, and competitive energy supply is necessary to align with the needs of sustainable devices. For this reason, a study for developing innovative dye-sensitized solar cells (DSSCs) based on microbial pigments is reported starting from Talaromyces atroroseus GH2. The fungus was cultivated by fermentation and the extracellular pigment extract was characterized by HPLC-DAD-ESI-MS analyses. The most abundant compound among the 22 azaphilone-type pigments identified was represented by PP-O. The device’s behavior was investigated in relation to electrolyte and pH for verifying the stability on time and the photovoltaic performance. Devices obtained were characterized by UV–vis measurements to verify the absorbance intensity and transmittance percentage. Moreover, photovoltaic parameters through photo-electrochemical measurements (I–V curves) and impedance characteristics by Electrochemical Impedance Spectroscopy (EIS) were determined. The best microbial device showed a short-circuit current density (Jsc) of 0.69 mA/cm2, an open-circuit photo-voltage (Voc) of 0.27 V and a Fill Factor (FF) of 0.60. Furthermore, the power conversion efficiency (PCE) of the device was 0.11%. Thus, the present study demonstrated the potential of microbial origin pigments for developing DSSCs.Graphical abstract

Utilization of Ipomoea batatas L. tuber extract for the development of dye-sensitized solar cell with modified electrode from rice husk ash

A dye-sensitized Solar Cell (DSSC) is a solar cell device that works based on electro photochemical principles in which sensitive dyes are absorbed in the layer of photoelectrode. The utilization of natural dyes as a substitute for high-cost material in DSSC has been developed. Purple sweet potato (Ipomoea batatas L.) has high anthocyanin content, is safe to use, and has renewable properties that can be used as dyes in a layer of DSSC. Purple sweet potatoes contain a lot of fiber, carbohydrates, vitamins C and B1, and minerals needed in DSSC. The semiconductor compiler to produce solar cells is expensive and requires many. Rice husk has a relatively high silica content, about 87-97%, that can be used as a low-cost and environmentally friendly silicon. The result of this study showed the absorbance peak for the mixture of extract and rice husk ash at 320 nm. DSSC fabrication obtained the highest efficiency of 1.1 x 10-3 with Imax = 0.0015 mA and Vmax = 0.02 mV. The physical characteristics were observed using SEM and XRD. Natural dye from purple sweet potato and rice husk ash semiconductors can be alternatives for DSSC production.

Structural and Optical Characteristics of Multilayer ZnO Nanorod:TiO2 by DC Magnetron Sputtering for Dye Sensitized Solar Cell (DSSC) Application

The development of Dye-Sensitized Solar Cell (DSSC) technology by utilizing various semiconductors has attracted attention. Among all types of semiconductors, the nanostructure of ZnO is selected due to their unique electrical properties and ease of preparation in various morphologies, and it has been considered a promising material to be applied in DSSC. In this research, the DC magnetron sputtering method was used to prepare ZnO thin films as an efficient alternative to press the charge recombination process that occurs in TiO2-based DSSC. Different thicknesses of TiO2 layers on the FTO conductive glass substrate were made through various sputtering deposition times, while the ZnO nanorod layers were made with a single layer using the hydrothermal method. We used XRD, SEM, UV-Vis, I-V meter, and EIS analysis. Based on these characterization we concluded that multilayer ZnO nanorod:TiO2 coating with a sputtering time of 60 minutes resulted the best performance of DSSC with an efficiency of 0.27%.

Analysis of ZnO and Tio2 as An Effective Nanomaterials for the Development of DSSCs: A Review

Energy crisis and global warming are the two major problems facing us today. The search for the best effective photo-anode film for the development of Dye-sensitized solar cells (DSSCs) – a third generation organic cell, is very essential. ZnO and TiO2 had been reportedly used as nanomaterial for the development of DSSCs. This paper presents reviewed works on the analysis of major properties of these nanomaterials. X-ray diffraction (XRD) analysis, Microstructural and compositional analysis, and photo-electrochemical analysis were considered for these materials. Our analysis agreed well with many researchers who had claimed that TiO is the best photo-anode material for DSSCs.

A hierarchical strategy for fabricating synergistic 3D network bio-based porous carbon and 0D niobium-based bimetallic oxides as counter electrodes for I- and Cu-mediated dye-sensitized solar cells with N719 and Y123 dyes

Designing cost-effective counter electrode (CE) catalysts with advanced nanostructures and exploring their application in different dye-electrolyte systems is crucial for the development of dye-sensitized solar cells (DSSCs). In this work, two types of 3D network bio-based porous carbon (3D-BPC) loaded 0D niobium-based bimetallic oxide nanohybrids (CoNb2O6/3D-BPC and NiNb2O6/3D-BPC) were synthesized using a hierarchical strategy. Benefiting from the optimization of the electron transport pathways and enrichment of catalytically active sites via the hierarchical 0D/3D structure, formed by 3D-BPC and MNb2O6 (M = Co, Ni), the catalytic reduction ability of MNb2O6/3D-BPC was significantly enhanced. To explore the photovoltaic performance of the MNb2O6/3D-BPC based DSSC, the I3−/I− electrolyte and N719 dye system and the Cu2+/Cu+ electrolyte and Y123 dye system were simultaneously employed. The solar cells assembled with the CoNb2O6/3D-BPC and NiNb2O6/3D-BPC CE exhibited device efficiencies of 7.03% and 7.14% in the N719-I3−/I− system, respectively, and 1.84% and 2.42% in the Y123-Cu2+/Cu+ system, respectively, which were almost equal to those of Pt under the same system. Additionally, MNb2O6/3D-BPC catalysts exhibited promising stability in I3−/I− electrolyte. This work provides guidance for the construction of low-cost and high-efficiency nanohybrid catalysts for new energy conversion devices.

Photon up-conversion in Er3+ ion-doped ZnO-Al2O3-BaO-B2O3 glass for enhancing the performance of dye-sensitized solar cells

One of the main limitations in the development of dye-sensitized solar cell (DSSC) is contributed by the optical losses that occur within the absorber layer due to spectral mismatch. DSSC typically only absorbs solar light within the visible region (i.e. up to 800 nm), while the photon energy in the infrared region remain unutilized. Here we report the integration of Er3+ ion-doped glass as up-conversion (UC) element in DSSC and study their effect on the photovoltaic performances. Several characterizations were conducted including physical, structural, optical, luminescence, and radiative properties on the glass sample, while current-voltage and incident photon-to-current conversion efficiency characterization were conducted to analyze the electrical properties of DSSC. The UC luminescence spectra of the glass sample under 800 nm excitation showed green light emissions that were located between 531 and 553 nm. The UC luminescence band of glass sample was confirmed suitable with the absorption band of Z907 dye. After placing the UC glass below the DSSC’s counter electrode side, the power conversion efficiency of DSSC were mostly positively affected by the presence of UC glass, where the highest improvement of around 7.21 % was obtained for DSSC coupled with 2.0 mol% of Er3+ ion-doped glass. The enhancement was primarily attributed to the improved light harvesting due to the UC mechanism within the device as indicated by the increase in external quantum efficiency and fill factor. Our contribution provides a simple yet versatile approach in improving DSSC performance via the application of a free standing Er3+ ion-doped up-conversion glass.

A thermal framework for preliminary evaluation of the development of dye-sensitized solar cells in temperate and warm climates

Environmental conditions influence the development of solar cell technologies; variables such as solar irradiation, wind speed, and ambient temperature influence the operating temperature of the cells, which affect their electrical performance; however, this effect may differ according to the solar technology. In the case of Dye-Sensitized Solar Cells (DSSCs), it is necessary to generate more studies to evaluate their behavior in different types of climates under real conditions, as it is known that, in comparison with Silicon cells, DSSCs show a lower decrease in their efficiency values when are subjected to high operating temperatures. Nevertheless, temperature is cited as the most important external variable affecting the stability of DSSCs. Therefore, in this paper, a new thermal numerical model is proposed to obtain the operating temperature contours of the DSSCs under real environmental conditions for two types of climates representative of Mexico (temperate and warm climate). The operating temperatures have been investigated as a function of solar irradiance, ambient temperature, wind speeds, and varying different electrolytes. It concludes that the efficiency gap between DSSCs and Silicon cells decreases as the operating temperature increases; moreover, an efficiency of 12.2% in DSSCs and 25.09% in Silicon cells were presented with 300 K of operating temperature, and an efficiency of 11.02% in DSSCs and 13.7% in Silicon cells were presented with 400 K of operating temperature. This concludes that DSSC technology might be an appropriate alternative for temperate and hot climates. DSSCs show a decrease in the efficiency of 9.76% compared to Silicon solar cells, which show a decrease in 50.1%.

Hydroxycinnamic acid derivatives for UV-selective and visibly transparent dye-sensitized solar cells

Naturally abundant dyes are very attractive for the development of dye-sensitized solar cells (DSSCs). Hydroxycinnamic acid derivatives, such as caffeic acid (CA), ferulic acid (FA), and p-coumaric acid (PA), were considered for the selective harvesting of ultraviolet A (UVA) (315–400 nm) photons. Their spectroscopic and electrochemical properties were investigated both theoretically and experimentally. They were further successfully adopted as photosensitizers in UV-selective and visibly transparent DSSCs, which exhibited a power conversion efficiency of 0.22–0.38% under AM (air mass) 1.5G (global) illumination (100 mW/cm2) and 3.40–3.62% under UVA irradiation (365 nm, 115.22 mW/cm2), with a corresponding visible light transmittance (VLT) of 49.07–43.72% and a general color rendering index (Ra) of 93–90.

Modified Poly(Vinyl Alcohol) Based Polymer Electrolyte for Dye Sensitized Solar Cells (DSSCs)

AbstractDue to increasing energy demand day by day, it must be necessary to have an alternate source of energy beside natural resources. Sun is the ultimate source of solar energy. So, from this solar energy, various types of solar cells are fabricated easily which are available in markets but these are somewhat costly. So, there is requirement of a low‐cost alternative to costly crystalline solar cells, which is fulfilled by dye sensitized solar cell (DSSC). Due to many potential properties like good ionic conductivity, thin film forming ability and many more, polymer electrolyte plays a vital role in improving the efficiency of DSSC which cannot be obtained by using volatile liquid electrolytes which are used earlier. The reliance of DSSCs on liquid electrolytes imposes a limit and restriction on the manufacture of DSSC modules. Liquid electrolyte faces many problems like corrosion, leakage, and evaporation. When the photoanode comes into touch with the volatilized redox‐electrolytes solution, the charge distribution at the semiconductor–electrolyte interface changes, resulting in photo corrosion on the photoelectrode. Furthermore, electron recombination at semiconductor–liquid electrolytes interfaces is discovered to cause performance losses. The concept of ionic conductivity observed in polymer materials when complexed with salt is a significant step forward in the development of DSSC devices.In this review, the fabrication of DSSC using polymer electrolyte, specifically PVA based solid polymer electrolyte is discussed. Here solid polymer electrolytes are of special interest due to thin film forming ability and overall good performance. Due to inherent properties like cost‐effectiveness, better tensile strength, and high hydrophilicity, PVA is chosen as a novel applicant for host polymer. The recent advancement of DSSC using modified PVA polymer electrolyte by incorporation of nanosized fillers, plasticizers, polymer blend, by the formation of conducting polymer electrolyte are discussed in detail. The improvement in ionic conductivity and enhanced efficiency of DSSC by using above mentioned factors are also discussed.

Investigation of dye-sensitized solar cell performance based on vertically aligned TiO2 nanowire photoanode

In this work, we present our results related to the development of Dye-Sensitized Solar Cells (DSSCs) based on vertically aligned TiO2-nanowire (NW) and Ag nanoparticle (NP) assisted vertically aligned TiO2-NW (TAT) photoanode fabricated by the glancing angle deposition (GLAD) technique on fluorine doped thin oxide (FTO) substrates. The scanning electron microscopy (SEM) analysis reveals that the Ag-NP assisted vertically aligned TiO2-NW photoanode was successfully deposited on FTO substrates. The average length and diameter of the NW have been measured to be ~ 350 nm and ~ 90 - 100 nm, respectively. Moreover, transmission electron microscopy (TEM) and X-ray diffraction (XRD) manifest the presence of small crystals of TiO2 and Ag. Further, the absorption spectrum analysis reveals that the incorporation of Ag-NP in TiO2-NW increases absorption in the visible region, but decreases the efficiency of the cell after the incorporation of the nanoparticle. The calculated bandgap of the annealed Ag-NP (30 nm) assisted TiO2-NW (TAT@30nm) sample from the photoluminescence (PL) graph is ~ 3.12 eV. Finally, it is observed that the TiO2-NW based DSSC device shows better performance in terms of photo conversion efficiency (PCE) compared to the TAT@30nm photoanode based device, with an efficiency of ~0.61 % from the former and ~ 0.24 % from the latter. This reduction in the efficiency of TAT@30nm based devices is due to the larger size of Ag-NP, in which the nanoaprticle acts as an electron sink and acts as a blocking layer.

Co-Sensitization Effects of Indoline and Carbazole Dyes in Solar Cells and Their Neutral-Anion Equilibrium in Solution.

Co-sensitization of two or more light-absorbing compounds on a TiO2 surface has recently become one of the most successful strategies in the development of dye-sensitized solar cells (DSSCs). The specific structure of the dyes for DSSCs implies that they can partly exist in anionic forms in popular solvents used for sensitization. Our study concerns the above two issues being analyzed in detail using the example of the popular carbazole (MK2) and indoline (D205) dyes, studied by stationary absorption and emission, femtosecond transient absorption (in complete cells and in the solutions), current-voltage measurements, DFT and TD-DFT theoretical calculations. After the addition of D205 to DSSC with MK2, the fill factor of the cells was improved, and the electron recombination between TiO2 and the dyes was blocked (observed on sub-nanosecond time scales). Thus, the active co-adsorbent can take the role of the typically used passive additive, like chenodeoxycholic acid. Evidence of the concentration-dependent equilibrium between neutral and anionic forms of dyes with different lifetimes was found in acetonitrile solutions (the best for sensitization), while in ethanol solution the dominant form was the anion (worse for sensitization). Our findings should help in better understanding the operation and optimization of DSSC.

The effect of conjugated groups for favourable molecular planarity and efficient suppression of charge recombination simultaneously of phenothiazine-based organic dyes for dye-sensitized solar cells

With the view to the poor coexistence between promoting molecular planarity towards improving the intramolecular charge transfer (ICT) effect and preventing charge recombination for dyes in Dye-sensitized solar cells (DSSCs). A novel 2-phenothiazine-amine-based organic dye PTZ-10 is synthesized and applied in DSSCs. The extra benzene and ethynyl conjugated groups are inserted as the isolation groups between the 2-phenothiazine-amine donor and benzothiadiazole auxiliary acceptor to obtain PTZ-17 in order to probe the possibility of reaching the aim of suppressing the charge recombination and strengthening molecular planarity synchronously in a better degree. Our photophysical measurement, electrochemical test and theoretical calculation demonstrate that the introduction of ethynyl and benzene is beneficial to the improvement of ICT effect and the inhibition of charge recombination, which can also be confirmed by the photovoltaic property and EIS study. Therefore, higher short-circuit photocurrent density (Jsc) and the open-circuit voltage (Voc) are exhibited in devices based on PTZ-17, along with the higher photoelectric conversion efficiency (PCE) up to 4.24 % relative to that of 3.37 % in PTZ-10. We demonstrated that the incorporation of different sizes of conjugated groups is a promising candidate to fine-tune the structure-performance of dye molecules in the development of DSSCs’ materials.

Polyimide-Based Covalent Organic Framework as a Photocurrent Enhancer for Efficient Dye-Sensitized Solar Cells

Covalent organic frameworks (COFs) are of great interest in the energy and optoelectronic fields due to their high porosity, superior thermal stability, and highly ordered conjugated architecture, which are beneficial for charge migration, charge separation, and light harvesting. In this study, polyimide COFs (PI-COFs) are synthesized through the condensation reaction of pyromellitic dianhydride (PMDA) with tris(4-aminophenyl) amine (TAPA) and then doped in the TiO2 photoelectrode of a dye-sensitized solar cell (DSSC) to co-work with N719 dye to explore their functionality. As a benchmark, the pristine DSSC without the doping of PI-COFs exhibits a power conversion efficiency of 9.05% under simulated one sun illumination. The doping of 0.04 wt % PI-COFs contributes an enhanced short-circuit current density (JSC) from 17.43 to 19.03 mA/cm2, and therefore, the cell efficiency is enhanced to 9.93%. The enhancement of JSC is attributed to the bifunctionality of PI-COFs, which enhances the charge transfer/injection and suppresses the charge recombination through the host (PI-COF)-guest (N719 dye) interaction. In addition, the PI-COFs also function as a cosensitizer and contribute a small quantity of photoinduced electrons upon sunlight illumination. Surface modification of oxygen plasma improves the hydrophilicity of PI-COF particles and reinforces the heterogeneous linkage between PI-COF and TiO2 nanoparticles, giving rise to more efficient charge injection. As a result, the champion cell exhibits a high power conversion efficiency of 10.46% with an enhanced JSC of 19.43 mA/cm2. This methodology of increasing solar efficiency by modification of the photoelectrode with the doping of PI-COFs in the TiO2 nanoparticles is promising in the development of DSSCs.

Fabrication of Dip Coated ZnO Nanorods for Organic Dye Sensitized Solar Cells

Abstract: Dye sensitized solar cell (DSSC) are new type of solar cell, has aroused worldwide attention which arises from its merits of low cost, ease of fabrication and environmental friendliness, etc. The development history, basic structure and working principle of the DSSC are introduced briefly, and the classification and development of DSSC are stated in detail. Dye sensitizers are divided into two major categories organic dyes and metal-organic compounds, and organic dyes can roughly be classified into several parts. A new form of solar cell is being investigated using a dye-sensitized solar cell (DSSC) using an inorganic semiconductor, due to the anticipated less costing solution to standard solid-state equipment. The formulation of effective solar cell contains countless semiconducting materials. This was an initiative of the researchers to study the fabricated of the natural dye sensitized solar cells for sol-gel dipping coated zinc oxide nanorod and also more voluminous in surface. Moreover, the corresponding assumptions and measures on how to improve the energy efficiency of the DSSCs are proposed, and finally the trends and promising prospects are presented. Keywords: ZnO Nanorods, Dye Sensitized Solar Cells (DSSC), Organic Solar Cell, Dip Coating Method

Hierarchical Photocatalytic Surfaces: From 1D to 3D Photoactive TiO2 Nanotubes Grown By Plasma Assisted Deposition Techniques

Photoactivity of TiO2 is of extensive recognition in applications like photocatalytic removal of pollutants, self-cleaning coatings, photoelectrochemical and photovoltaic cells and optical filters [1, 2]. Photocatalytic activity is affected by both the TiO2 structure and microstructure. For example, parameters as crystal sizes, texturization, nano and microscale arrangement, and interface conditioning and engineering [3] have been demonstrated to determine the formation and migration to the surface of electron-hole pairs responsible for the photoactivity response [3]. Thus, A successful approach to enhance the specific surface area and light harvesting is the use of highly porous structures such as nanoparticles, nanotubes, nanowires, or 3D nanoarchitectures. In this latter case, the hierarchical distribution of the semiconducting oxide is expected to prompt light scattering effects which might allow high efficiencies in photocatalytic pollutant removal for finely controlled nanoscale motives.In this communication, we propose the development of photoactive highly porous TiO2 nanostructures, forming 1D nanotubes and 3D hierarchical systems as nanotrees and multistack of nanotrees. These nanoarchitectures are fabricated by the combination of plasma enhanced chemical vapour deposition of crystalline TiO2 layers with the use of small-molecule organic nanowires as 1D and 3D soft-templates. This same synthetic approach has been exploited recently in the development of dye-sensitized solar cells [4], piezoelectric nanogenerators [5], and icephobic, freezing-delay, surfaces [6].The study of nanostructure shape, density, and entanglement as well as the combination of crystalline phases in the same nanostructure are revealed as key factors controlling the photocatalytic performance of the system. A thorough characterization analysis is presented including XRD, XPS, Raman, SEM, and TEM providing crucial information on the chemical composition, structure, and microstructure. Moreover, wetting characterization has been also performed to relate the surface tension to the photoactivity of TiO2 nanostructures. Photoactivity has been studied in a home-made system able to be illuminated with UV irradiation and the “in-situ” optical monitoring of different dye concentrations, like methyl orange dye, methylene blue, or rhodamine 6G. Thus, photocatalysis behavior has been evaluated and associated with the nanostructured configuration.[1] M. Grätzel, Nature 2001, 414, 338[2] F. Parrino, A. Ramakrishnan, H. Kisch, Angew. Chem. 2008, 120, 7215[3] P. Romero-Gomez, A. Borras, A. Barranco. J.P. Espinos, A.R. Gonzalez-Elipe ChemPhysChem 2010, 12 (1) 191[4] A.N. Filippin, M. Macías-Montero, A. Borras, et al. Scientific Reports 2017, 7, 9621[5] A.N. Filippin, J.R. Sanchez-Valencia, A. Borras, et al. Nano Energy 2019, 58, 476[6] M. Alcaire, C. Lopez-Santos, A. Borras, et al. Langmuir 2019, 35(51) 16876 Acknowledgements. We thank the AEI-MICINN (PID2019-110430GB-C21 and PID2019-109603RA-I0), the Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía (PAIDI-2020 through projects US-1263142, ref. AT17-6079, P18-RT-3480), and the EU through cohesion fund and FEDER 2014–2020 programs for financial support. CLS and JS-V thank the University of Seville through the VI PPIT-US and (JS-V) the Ramon y Cajal Spanish National programs. The project leadings to this article have received funding from the EU H2020 program under the grant agreements 851929 (ERC Starting Grant 3DScavengers) and 899352 (FETOPEN-01-2018-2019-2020 - SOUNDofICE).

On the Use of PEDOT as a Catalytic Counter Electrode Material in Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) emerged in the early 1990s as a promising alternative to the classic silicon-based solar cell due to their unique combination of low cost, ease of fabrication, color palette for building integration, and high efficiency in indoor applications. This review article describes the fabrication and the properties of poly (3,4-ethylenedioxythiophene) (PEDOT)-based catalytic counter electrodes (CEs) for DSSCs. In particular, the electrochemical reactivity PEDOT CEs used in conjunction with alternative redox mediators for DSSCs is outlined. Among alternative redox shuttles, cobalt and copper complexes, as well as totally organic thiolate/disulfide, have been considered. Finally, PEDOT can also be used as a hole conductor material in electrolyte-free solid-state dye-sensitized solar cells. This review clearly shows that the progress in DSSCs development is strongly linked to the introduction of PEDOT as a new counter electrode material.