Nanoarchitectures in dye-sensitized solar cells: metal oxides, oxide perovskites and carbon-based materials

Iron-Sensitized Solar Cells (FeSSCs)

ConspectusThe harvesting and conversion of solar energy have become a burning issue for our modern societies seeking to move away from the exploitation of fossil fuels. In this context, dye-sensitized solar cells (DSSCs) have proven to be trustworthy alternatives to silicon-based cells with advantages in terms of transparency and efficiency under low illumination conditions. These devices are highly dependent on the ability of the sensitizer that they contain to collect sunlight and transfer an electron to a semiconductor after excitation. Ruthenium and polypyridine complexes are benchmarks in this field as they exhibit ideal characteristics such as long-lasting metal-ligand charge transfer (MLCT) states and efficient separation between electrons and holes, limiting recombination at the dye-semiconductor interface. Despite all of these advantages, ruthenium is a noble metal, and the development of more sustainable energy devices based on earth-abundant metals is now a must. A quick glance at the periodic table reveals iron as a potential good candidate, since it belongs to the same group of ruthenium, which suggests similar electronic properties. However, striking photophysical differences exist between ruthenium(II) polypyridyl complexes and their Fe(II) analogues, the latter suffering from short-lived MLCT states resulting of their ultrafast relaxation into metal-centered (MC) states. Pyridyl-N-heterocyclic carbenes (pyridylNHC) brought a strong σ-donor character required to promote a higher ligand field splitting of the iron d orbitals. This induces destabilization of the MC states over the MLCT manifold and a consequent slowdown of the excited states deactivation providing iron(II) complexes with tens of picoseconds lifetimes, making them more promising for applications in DSSCs. This Account highlights our recent advances in the development and characterization of iron-sensitized solar cells (FeSSCs) with a focus on the design of efficient sensitizers going from homoleptic to heteroleptic complexes (bearing different anchoring groups) and the tuning of electrolyte composition. Our rational approach led to the best photocurrent and efficiency ever reported for an iron sensitized solar cell (2% PCE and 9 mA/cm2) using a cosensitization process. This work clearly evidences that the solar energy conversion based on iron complex sensitization is now an opened and fruitful route.

The Potential of Electrospinning to Enable the Realization of Energy-Autonomous Wearable Sensing Systems

The market for wearable electronic devices is experiencing significant growth and increasing potential for the future. Researchers worldwide are actively working to improve these devices, particularly in developing wearable electronics with balanced functionality and wearability for commercialization. Electrospinning, a technology that creates nano/microfiber-based membranes with high surface area, porosity, and favorable mechanical properties for human in vitro and in vivo applications using a broad range of materials, is proving to be a promising approach. Wearable electronic devices can use mechanical, thermal, evaporative and solar energy harvesting technologies to generate power for future energy needs, providing more options than traditional sources. This review offers a comprehensive analysis of how electrospinning technology can be used in energy-autonomous wearable wireless sensing systems. It provides an overview of the electrospinning technology, fundamental mechanisms, and applications in energy scavenging, human physiological signal sensing, energy storage, and antenna for data transmission. The review discusses combining wearable electronic technology and textile engineering to create superior wearable devices and increase future collaboration opportunities. Additionally, the challenges related to conducting appropriate testing for market-ready products using these devices are also discussed.

Comparative Study of TiO2, ZnO, and Nb2O5 Photoanodes for Nitro-Substituted Naphthoquinone Photosensitizer-Based Solar Cells

This research focuses on the first demonstration of NO2Lw (2-hydroxy-3-nitronaphthalene-1,4-dione) as a photosensitizer and TiO2, ZnO, and Nb2O5 as photoanode materials for dye-sensitized solar cells (DSSCs). The metal-free organic photosensitizer (i.e., nitro-group-substituted naphthoquinone, NO2Lw) was synthesized for this purpose. As a photoanode material, metal oxides, such as TiO2, ZnO, and Nb2O5, were selected. The synthesized NO2Lw contains an electron-withdrawing group (-NO2) and anchoring groups (-OH) that exhibit absorption in the visible range. The UV-visible absorbance spectrum of NO2Lw demonstrates the absorption ascribed to ultraviolet and visible region charge transfer. The NO2Lw interacts with the TiO2, ZnO, and Nb2O5 photoanode, as shown by bathochromic shifts in wavelengths in the photosensitizer-loaded TiO2, ZnO, and Nb2O5 photoanodes. FT-IR analysis also studied the bonding interaction between NO2Lw and TiO2, ZnO, and Nb2O5 photoanode material. The TiO2, ZnO, and Nb2O5 photoanodes loaded with NO2Lw exhibit a shift in the wavenumber of the functional groups, indicating that these groups were involved in loading the NO2Lw photosensitizer. The amount of photosensitizer loading was calculated, showing that TiO2 has higher loading than ZnO and Nb2O5 photoanodes; this factor may constitute an increased JSC value of the TiO2 photoanode. The device performance is compared using photocurrent-voltage (J-V) curves; electrochemical impedance spectroscopy (EIS) measurement examines the device's charge transport. The TiO2 photoanode showed higher performance than the ZnO and Nb2O5 photoanodes in terms of photoelectrochemical properties. When compared to ZnO and Nb2O5 photoanodes-based DSSCs, the TiO2 photoanode Bode plot shows a signature frequency peak corresponding to electron recombination rate toward the low-frequency region, showing that TiO2 has a greater electron lifetime than ZnO and Nb2O5 photoanodes based DSSCs.

Photovoltaic performance of MOF-derived transition metal doped titania-based photoanodes for DSSCs

The enduring effort toward stabilizing and improving the efficiency of dye-sensitized solar cells (DSSCs) has stirred the solar research community to follow innovative approaches. Current research centered on electrode materials design, which improves photoanodes' light-harvesting efficiency (LHE). Metal-Organic Frameworks (MOFs) are a new family of materials that can be used as competent materials due to their desirable qualities, including high porosity, flexible synthesis methodology, high thermal and chemical stability, and good light-harvesting capabilities. MOF-derived porous photoanodes can effectively adsorb dye molecules and improve LHE, resulting in high power conversion efficiency (PCE). Doping is a prospective methodology to tune the bandgap and broaden spectral absorption. Hence, a novel and cost-effective synthesis of high surface area transition metal (TM) doped TiO₂ nanocrystals (NCs) via the metal-organic framework route for DSSCs is reported here. Among the TM dopants (i.e., Mn, Fe, Ni), a remarkable PCE of 7.03% was obtained for nickel-doped samples with increased Jsc (14.66 mA/cm²) due to the bandgap narrowing and porous morphology of TiO₂. The findings were further confirmed using electrochemical impedance spectroscopy (EIS) and dye-desorption experiments. The present study expedites a promising way to enhance the LHE for many innovative optoelectronic devices.

Naphthoquinoneoxime-Sensitized Titanium Dioxide Photoanodes: Photoelectrochemical Properties

Naphthoquinoneoxime derivatives, viz., LwOx, 3-hydroxy-4-(hydroxyimino)naphthalen-1 (4H)-one; PthOx, 3-hydroxy-4-(hydroxyimino)-2-methylnaphthalen-1(4H)-one; and Cl_LwOx, 2-chloro-3-hydroxy-4-(hydroxyimino)naphthalen-1(4H)-one, are used in fabrication of dye-sensitized solar cells (DSSCs). The photophysical and electrochemical properties of the sensitizers were studied. The HOMO-LUMO energy gaps of the sensitizers (LwOx, PthOx, and Cl_LwOx) calculated by using the intersection of UV-visible and fluorescence spectra are 2.85, 2.71, and 2.87 eV, respectively. The energy band alignment energy level of the sensitizer, that is, the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO), should match with the energy level of the TiO₂ conduction band and the redox potential of iodine/triiodide electrolyte to allow smooth electron transfer. The electrochemical characterization of sensitizers was done to find the LUMO and HOMO level of the sensitizer. It shows that the LUMO level of (LwOx, PthOx, and Cl_LwOx) is above the conduction band position of TiO₂. Electrochemical impedance spectroscopy was used to study the charge transport resistance and electron lifetime of DSSCs. The charge transport resistance at the TiO₂ |electrolyte|counter electrode interface was reduced in the Cl_LwOx device; thus, the electron lifetime of Cl_LwOx was enhanced compared to LwOx and PthOx sensitizers. The fabricated device was characterized using photocurrent density-voltage (J-V) measurement. It is observed that there was an enhancement in the overall power conversion efficiency (η) of the DSSCs fabricated by using Cl_LwOx sensitizers as compared to LwOx and PthOx sensitizer-loaded photoanodes. Enhancement in power conversion efficiency, that is, photovoltage and photocurrent, is achieved due to the chlorine substituent. Thus, the chlorine substituent naphthoquinoneoxime pushes the electron density, enhancing the pushing nature and facilitating the lone pair present in the N-OH moiety to attach to TiO₂ more strongly.

Solar Energy Materials-Evolution and Niche Applications: A Literature Review

The demand for energy has been a global concern over the years due to the ever increasing population which still generate electricity from non-renewable energy sources. Presently, energy produced worldwide is mostly from fossil fuels, which are non-renewable sources and release harmful by-products that are greenhouses gases. The sun is considered a source of clean, renewable energy, and the most abundant. With silicon being the element most used for the direct conversion of solar energy into electrical energy, solar cells are the technology corresponding to the solution of the problem of energy on our planet. Solar cell fabrication has undergone extensive study over the past several decades and improvement from one generation to another. The first solar cells were studied and grown on silicon wafers, in particular single crystals that formed silicon-based solar cells. With the further development in thin films, dye-sensitized solar cells and organic solar cells have significantly enhanced the efficiency of the cell. The manufacturing cost and efficiency hindered further development of the cell, although consumers still have confidence in the crystalline silicon material, which enjoys a fair share in the market for photovoltaics. This present review work provides niche and prominent features including the benefits and prospects of the first (mono-poly-crystalline silicon), second (amorphous silicon and thin films), and third generation (quantum dots, dye synthesized, polymer, and perovskite) of materials evolution in photovoltaics.

Simple preparation of in-situ oxidized titanium carbide MXene for photocatalytic degradation of catechol

Photocatalytic system has been widely applied to treat the highly toxic and refractory aromatics sewage water pollution problem. However, developing highly active and excellent durability photocatalysts is always the long-term...

Effect of ZnO Nanomaterial and Red and Green Cabbage Dyes on the Performance of Dye-Sensitised Solar Cells

Visible light can be converted into electricity using dye sensitised solar cells (DSSCs), with their performance mainly based on the type of dye used as a sensitiser. Currently, dyes extracted from natural sources are highly preferred by researchers in this field. Natural dyes reduce the high cost of metal complex sensitisers and replace expensive processes of chemical synthesis with simple extraction processes. Natural dyes are environmentally friendly, abundant, easily extractable, and safe. Their application has become a promising development in DSSC technology. In this study, two natural dyes extracted from the plant leaves of green cabbage (GC) and red cabbage (RC) that were used as sensitisers. The performance characteristics of RC and GC extracts were investigated using both cyclic voltammetry and amperometry methods for solar cell detection. At an extraction temperature of 60 °C maintained for 8 h under optimum conditions, the measured values of maximum power (Pm), fill factor (FF), and efficiency (η) were 1.36 mW/cm2, 92.34%, and 0.161% for RC, and 0.349 mW/cm2, 44.19%, and 0.095% for GC, respectively. The RC and GC extracts exhibited excellent electrochemical performance with respect to current density potential and good cycling stability.

Semiconductors as Effective Electrodes for Dye Sensitized Solar Cell Applications

As proficient photovoltaic devices, dye-sensitized solar cells (DSSCs) have received considerable consideration in recent years. In order to accomplish advanced solar-to-electricity efficiency and increase long-term functioning stability, improvements in the configuration structure of DSSCs are essential, as is an understanding of their elementary principles. This work discusses the application of different semiconductor constituents designed for effective DSSCs. The main parameters crucial to fabrication of DSSC electrodes in nano-porous semiconductor structures are high surface area and large pore size. Different inorganic semiconductor materials are used to load sensitizer dyes, which absorb a lot of light and induce high photocurrent for efficient DSSCs. The first section of the review covers energy sources, photovoltaics, and the benefits of solar cells in daily life, while the second part includes the various types of semiconductors applied in DSSC applications. The final section provides a brief review of future perspectives for DSSCs and a survey of semiconductor materials proposed for solar cell applications.

Effects of ion migration and improvement strategies for the operational stability of perovskite solar cells

The fundamental factor affecting the stability of perovskite solar cells, ion migration, has been reviewed, which is found to be closely related to the degradation of perovskite solar cells. Characterization methods like impedance spectroscopy and galvanostatic measurement to identify ion migration in perovskite films have been reviewed. The influence of light on ion migration was further discussed, which could largely explain the photo-stability decay in most perovskite solar cells. Finally, several solutions to inhibit ion migration for better operational stability of perovskite solar cells were summarized, including bulk passivation, interface passivation and grain boundary passivation. Several strategies have also been proposed to further improve the stablity of perovskite solar cells.

A single layer deposition of Li-doped mesoporous TiO2 beads for low-cost and efficient dye-sensitized solar cells

Cost-effective DSCs with superior electronic properties are gained by a reduction in electronic trap states and outstanding light scattering and harvesting.

Well-dispersed Te-doped mesoporous carbons as Pt-free counter electrodes for high-performance dye-sensitized solar cells

A tellurium-doped carbon nanomaterial (Te-MC(P)) was newly developed by the soft-templated carbonization of the PAN-b-PBA copolymer with poly(3-hexyltellurophene). Te-MC(P) was characterized with various characterization methods, including the nitrogen sorption isotherm measurement (BET), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS), which reveal that the Te atoms are homogeneously dispersed in the three-dimensional hierarchical, graphite-like mesoporous carbon matrix with a Te doping level of 0.27 atom %. Based on the characterization results, the electrocatalytic ability of Te-MC(P) was evaluated by using a symmetrical dummy cell test with both Co(bpy)32+/3+ (bpy = 2,2'-bipyridine) and I-/I3- redox electrolytes as counter electrodes (CEs). The Te-MC(P) CEs showed remarkably lower charge-transfer resistance (Rct) values by approximately 10 times in the electrochemical impedance spectroscopy (EIS) measurement, compared to the counterpart platinum (Pt) and the tellurium-based material (Te-MC(A)), prepared with a telluric acid precursor that has a lower Te doping level of 0.15 at%. As a result, the excellent electrocatalytic ability of Te-MC(P) resulted in the improvement of photovoltaic performance. The power conversion efficiencies (PCEs) of Te-MC(P)-based dye-sensitized solar cells (DSSCs) were 12.69% for the Co(bpy)32+/3+ redox electrolyte with the SGT-021 porphyrin dye and 9.73% for the I-/I3- redox electrolyte with the N719 ruthenium dye. Furthermore, Te- MC(P) CEs exhibited remarkable electrochemical stability in the two redox electrolytes. These results could suggest that the Te-MC(P) CE is one of the best promising alternatives to Pt CEs as a low-cost, highly stable and efficient electrocatalytic CE for practical applications.

Facile synthesis of gold and platinum doped titanium oxide nanoparticles for antibacterial and photocatalytic activity: A photodynamic approach

A simple method has been needed to synthesize nanoparticles (NPs) to avoid environmental pollution, an alternative chemical and physical method. This current study deals with phytosynthesis of gold (Au) and platinum (Pt) metal doped with titanium oxide (TiO₂) NPs using Enterolobium saman bark extract. This extract plays a vital role in reducing and stabilizing Au and Pt doped into the TiO₂ NPs lattices. Phytosynthesized samples were characterized by XRD, SEM, ED-XRF, TEM, FTIR, Raman, and UV-vis-DRS analyses. The metal doping effect has decreased bandgap energy and particle size, whereas increased conductivity for TiO₂/M-Au and TiO₂/M-Pt NPs compared to pristine TiO₂ NPs. Phytosynthesized NPs were fabricated for dye-sensitized solar cell (DSSC) and photocatalytic behaviour against methylene blue (MB) dye was studied. An obtained result demonstrates that TiO₂/M-Au NPs have excellent feasibility for applying DSSC and photocatalytic application due to particle size, crystallite size, absorption ability, and bandgap energy. Besides, synthesized samples were measured with cyclic voltammetry and impedance spectroscopy found that the metal doping is drifted the dielectric and increases that the metal doping is drifted the dielectric increases electro-catalytic of the TiO₂. Different concentrations of all NPs were tested against Escherichia coli MTCC 40 and S. aureus ATCC 6633 bacteria by a well-diffusion method. The 10 mg concentration of all NPs showed better antibacterial activity. However, we believe that the proposed simple phytosynthesized method provides an efficient way to overcome the chemical and physical methods.

Performance evaluation of a low-cost, novel vanadium nitride xerogel (VNXG) as a platinum-free electrocatalyst for dye-sensitized solar cells

A vanadium nitride xerogel (VNXG) was synthesised by a simple and effective method of ammonialising a vanadium pentoxide xerogel at a higher temperature. Xerogel-structured materials possess salient features such as high surface area, tunable porosity and pore size that result in enhancing the catalytic activity by a fast electron-transport pathway and increase electrolyte diffusion channels. Metal nitrides are reported as promising alternate low-cost counter electrodes to replace the conventional and expensive platinum (Pt) counter electrode. Though few studies are reported on aerogel-based CEs for DSSCs, the present work is the first attempt to synthesize and evaluate the performance of xerogel-structured metal nitrides as counter electrode materials for dye-sensitized solar cells. The synthesized material was well characterized for its structural and morphological characteristics and chemical constituents by photoelectron spectroscopy. Finally, the VNXG was tested for its electrocatalytic performance as a choice of counter electrodes for dye-sensitized solar cells (DSSCs). The photo-current studies were performed under standard 1 SUN, class AAA-simulated illumination with AM1.5G. The consolidated results revealed that the vanadium nitride xerogel exhibited good photocatalytic activity and low charge transfer resistance. This identified it as a promising low-cost counter electrode (CE) material for dye-sensitized solar cells. The photo-current conversion efficiency of the vanadium nitride xerogel CE-based DSSC reached 5.94% comparable to that of the conventional thermal decomposed Pt CE-based DSSC, 7.38% with the same iodide/triiodide electrolyte system. Moreover, the 28 days stability study of VNXG CE DSSCs provided an appreciably stable performance with 37% decrement in the PCE under the same test condition.

A sonochemical assisted synthesis of hollow sphere structured tin (IV) oxide on graphene oxide sheets for the low-level detection of environmental pollutant mercury in biological samples and foodstuffs

In modern approaches for nanomaterials synthesis, ultrasonication plays an important role in providing the larger surface area and smaller crystalline size properties that are favorable to electrochemical techniques. Herein, we report the tin (IV) oxide on graphene oxide nanoparticles were synthesized (SnO₂@GO NPs) by ultrasonic methodology (UZ SONOPULS HD 3400 Ultrasonic homogenizer) with the total power of 400 W and the (frequency of 20 kHz; 140 W/dm³). The formation of as-prepared SnO₂@GO NPs and its surface morphology were scrutinized over XRD, XPS, TEM, and FESEM. Besides, the sonochemically prepared SnO₂@GO NPs were employed for the determination of environmental hazardous mercury (Hg). As a result, the modified electrode acquired a very low-level detection limit of 1.2 nM with a wider range of 0.01-10.41-µM and 14.52-225.4-µM for the detection of Hg. Finally, the practical applicability of SnO₂@GO NPs in spiked human blood serum and tuna fish samples shows appreciable found and recovery values. .

Investigating Various Permutations of Copper Iodide/FeCu Tandem Materials as Electrodes for Dye-Sensitized Solar Cells with a Natural Dye

This work presents the synthesis and deposition of CuI and FeCu materials on copper substrates for dye-sensitized solar cell applications. FeCu is a metastable alloy of iron and copper powders and possesses good optical and intrinsic magnetic properties. Coupled with copper iodide as tandem layers, the deposition of these two materials was permutated over a pure copper substrate, characterized and then tested within a solar cell. The cell was sensitized with a natural dye extracted from a local desert plant (Calotropis gigantea) and operated with an iodine/triiodide electrolyte. The results show that the best layer arrangement was Cu/FeCu/CuI, which gave an efficiency of around 0.763% (compared to 0.196% from reported cells in the literature using a natural sensitizer).

Zinc phthalocyanines as light harvesters for SnO2-based solar cells: a case study

SnO₂ nanoparticles have been synthesized and used as electron transport material (ETM) in dye sensitized solar cells (DSSCs), featuring two peripherally substituted push-pull zinc phthalocyanines (ZnPcs) bearing electron donating diphenylamine substituents and carboxylic acid anchoring groups as light harvesters. These complexes were designed on the base of previous computational studies suggesting that the integration of secondary amines as donor groups in the structure of unsymmetrical ZnPcs might enhance photovoltaics performances of DSSCs. In the case of TiO₂-based devices, this hypothesis has been recently questioned by experimental results. Herein we show that the same holds for SnO₂, despite the optimal matching of the optoelectronic characteristics of the synthesized nanoparticles and diphenylamino-substituted ZnPcs, thus confirming that other parameters heavily affect the solar cells performances and should be carefully taken into account when designing materials for photovoltaic applications.

Diatom frustules enhancing the efficiency of gel polymer electrolyte based dye-sensitized solar cells with multilayer photoelectrodes

The incorporation of nanostructures that improve light scattering and dye adsorption has been suggested for dye-sensitized solar cells (DSSCs), but the manufacture of photonic and nanostructured materials with the desired properties is not an easy task. In nature, however, the process of light-harvesting for photosynthesis has, in some cases, evolved structures with remarkable wavelength-sensitive light-trapping properties. The present work is focused on enhancing the efficiency of quasi solid-state DSSCs by capitalizing on the light trapping properties of diatom frustules since they provide complex 3-dimensional structures for scattering and trapping light. This study reports a promising approach to prepare TiO₂ nanocrystal (14 nm) based photo-electrodes by utilizing the waveguiding and photon localization effects of nanostructured diatom frustules for enhancing light harvesting without deteriorating the electron conduction. Single and double-layered photo-electrodes were prepared with different frustule/nanocrystal combinations and conformations on transparent conductive oxide substrates. This study clearly reports impressive efficiency and short circuit current density enhancements of about 35% and 39%, respectively, due to the incorporation of diatom frustules extracted from a ubiquitous species. The SEM images obtained in this work reveal that the produced thin films had a remarkable surface coverage of evenly distributed frustules within the TiO₂ nanoparticle layer. To the best of our knowledge, this study reports the first quasi solid-state DSSC based on a photo-electrode with incorporated bio-formed nanostructures.

A frontier Zn- and N-rich complex grafted onto reduced graphene oxide for the electrocatalysis of dye-sensitized solar cells

A soluble small molecule nitrogen-rich zinc-organic framework for a graphene-based high-efficiency electrocatalytic electrode.

Quantum Dot Based Solar Cells: Role of Nanoarchitectures, Perovskite Quantum Dots, and Charge-Transporting Layers

Quantum dot solar cells (QDSCs) are attractive technology for commercialization, owing to various advantages, such as cost effectiveness, and require relatively simple device fabrication processes. The properties of semiconductor quantum dots (QDs), such as band gap energy, optical absorption, and carrier transport, can be effectively tuned by modulating their size and shape. Two types of architectures of QDSCs have been developed: 1) photoelectric cells (PECs) fabricated from QDs sensitized on nanostructured TiO₂ , and 2) photovoltaic cells fabricated from a Schottky junction and heterojunction. Different types of semiconductor QDs, such as a secondary, ternary, quaternary, and perovskite semiconductors, are used for the advancement of QDSCs. The major challenge in QDSCs is the presence of defects in QDs, which lead to recombination reactions and thereby limit the overall performance of the device. To tackle this problem, several strategies, such as the implementation of a passivation layer over the QD layer and the preparation of core-shell structures, have been developed. This review covers aspects of QDSCs that are essential to understand for further improvement in this field and their commercialization.

DFT calculations reveal pronounced HOMO-LUMO spatial separation in polypyrrole-nanodiamond systems

The low-cost efficient generation of renewable energy and its blending with societal lifestyle is becoming increasingly pervasive. Diamond-based inorganic-organic hybrid systems may have an immense, yet still mostly unexplored, potential in photovoltaic solar cells applications. In this work, we study the interactions of polypyrrole (PPy) with diamond nanoparticles (so-called nanodiamonds, NDs) by computational density functional theory (DFT) methods. We compute the structural and electronic properties of such hybrid organic-inorganic systems. During modeling, PPy is chemisorbed and physisorbed on (111) and (100) ND edge-like surface slabs terminated with oxygen, hydroxyl, carboxyl, and anhydride functional groups, i.e., in the arrangements most commonly found in real NDs. Moreover, NDs terminated with an amorphous surface layer (a-C:H, a-C:O) are considered to approach realistic conditions even further. In a predominant number of cases, we obtain the spatial separation of HOMO and LUMO at the interface, facilitating exciton dissociation. Further, there is a favorable energy level alignment for charge transport. The theoretical results, therefore, show the promising potential of PPy-ND composites in photovoltaic applications.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Rhodanine-based light-harvesting sensitizers: a rational comparison between 2-(1,1-dicyanomethylene)rhodanine and rhodanine-3-acetic acid

Photophysical, electrochemical and theoretical characterization of new rhodanine-based dyes for DSSC applications, a comparison of the photovoltaic performances of 2-(1,1-dicyanomethylene)rhodanine (DR) and rhodanine-3-acetic acid (RAA).