State Dye-sensitized Solar Cells Research Articles

Nanostructured Coordination Polymers for Solid State Dye-Sensitized Solar Cells

Dye-sensitized solar cells have the potential to provide a viable source of renewable energy to help decarbonize our economy and power wearable devices. With their exceptional performance in diffused light under indoor conditions, DSCs remain competitive for powering the next digital revolution forming the internet of things.[1] Conventional DSCs use a liquid electrolyte; however, a lot of research is going into replacing it with a solid hole transporter material to make the technology better suited for scale-up and commercialization. We work with an emerging class of materials called nanostructured coordination polymers (CP) and explore their application as a hole transport material aimed at creating high performing monolithic solid-state DSCs.Nanostructured CPs possess the highly ordered structure of inorganic materials combined with the chemically tailorable properties and low cost of organics.[2] Thanks to their high external surface area, aspect ratios, nanoscopic dimensions and novel electronic and optical properties, CPs have been found to outperform their precursors in a wide range of applications and are ideal for evaluation as solid-state hole transport materials in DSCs. CPs facilitate the formation of extended polymeric structure of metal ions and the coordinating atoms of the organic ligands. The systems are designed by taking the following conditions into consideration- the energy overlap of the orbitals of the metal ions and the coordinating atoms and their relative electronegativities. Incorporating redox-active metal centres into conducting polymer substrates thus creates highly efficient redox conductivity. Metal centres can provide efficient sites for redox conductivity but can also act as thermodynamic sinks that trap/localize charges due to their low-lying energetic states.[3] Based on these design criteriae, we explore Copper benzenetetrathiol (Cu-BTT) as an ideal candidate for hole transporting roles in solid state dye sensitized solar cells.We show that Cu-BTT is formed by alternating Cu2+ and C6H2S4 2- units with pairs of chelating S atoms from the ligand coordinating around the metal centre. Formation of 1D chain-type nanowires is a good strategy for through bond charge transport. The as-prepared pristine Cu-BTT coordination polymers were found to exhibit a conductivity of the order 10-6 S cm-1. Upon altering the technique used for thin film preparation, the conductivity was found to increase by up to an order of a magnitude. Layer by layer assembly of the coordination polymer was found to be the best performing, giving a fairly uniform epitaxial growth of Cu-BTT over large areas and showing conductivities of the order 10-3 S cm-1 without additives. Using AFM imaging studies, we show that this morphology creates the formation of highly interconnected networks of CuBTT nanowires which improves the conductivity. We also demonstrate that epitaxially grown Cu-BTT also shows better performance as a hole transport material in the DSSC devices as compared to Cu-BTT films prepared using drop casting or spin-coating technique. This is because during epitaxial growth the precursors get a better chance to infiltrate the pores in the mesoporous layer and the polymeric HTM forms direct contact with the dye molecules. This is corroborated by photoinduced absorption spectroscopy (PIA) measurements where we observe that the ground state bleach and absorption peaks of the dye (Y123) disappear upon introduction of the epitaxially grown CuBTT HTM. This demonstrates an efficient and complete reduction of the oxidized dye molecules therefore proving that CuBTT nanowire type 1D coordination polymers can be utilized successfully as hole transport layers in solid state dye sensitised solar cells. This work shows that 1D coordination polymers hold significant potential as solid-state hole transport materials to create monolithic solid state DSSCs with improved performance. REFERENCES [1] M. Freitag et al., “Dye-sensitized solar cells for efficient power generation under ambient lighting,” Nat. Photonics, vol. 11, no. 6, pp. 372–378, 2017, doi: 10.1038/nphoton.2017.60.[2] K. Sasitharan et al., “Metal‐Organic Framework Nanosheets as Templates to Enhance Performance in Semi‐Crystalline Organic Photovoltaic Cells,” Adv. Sci., vol. 2200366, p. 2200366, 2022, doi: 10.1002/advs.202200366.[3] A. J. Clough et al., “Room Temperature Metallic Conductivity in a Metal − Organic Framework Induced by Oxidation,” 2019, doi: 10.1021/jacs.9b06898. Figure 1

Structural, Thermal, and Electrical Properties of Poly(Ethylene Oxide)-Tetramethyl Succinonitrile Blend for Redox Mediators.

An all-solid–state dye-sensitized solar cell is one of the non-fossil fuel-based electrochemical devices for electricity generation in a high-temperature region. This device utilizes a redox mediator, which is a fast ion-conducting solid polymer electrolyte (SPE). The SPE makes the device economical, thinner, and safer in high-temperature regions. The SPE generally has a form of matrix−plasticizer−redox salts. Succinonitrile (SN) is generally employed as a plasticizer for reducing the crystallinity of poly(ethylene oxide), abbreviated as PEO, a common polymeric matrix. In the present paper, the structural and thermal properties of tetramethyl succinonitrile (TMSN) were compared with SN for its application as a solid plasticizer. TMSN and SN both are plastic crystals. TMSN has four methyl groups by replacing the hydrogen of the SN, resulting in higher molecular weight, solid–solid phase transition temperature, and melting temperature. We thoroughly studied the structural, thermal, and electrical properties of the [(1−x)PEO: xTMSN] blend for utilizing it as a matrix, where x = 0–0.25 in mole fraction. The FT-IR spectra and XRD patterns of the blends exhibited PEO-alike up to x = 0.15 mole and TMSN-alike for x > 0.15 mole. Differential scanning calorimetry revealed formation of a eutectic phase from x = 0.1 mole and phase separation from x = 0.15 mole. The blends with x = 0.1–0.15 mole had a low value of PEO crystallinity. Thermogravimetric analysis showed thermal stability of the blends up to 75 °C. The blends exhibited electrical conductivity, σ25°C more than 10−9 S cm−1, and Arrhenius behavior (activation energy, ~0.8 eV) in a temperature region, 25–50 °C.

Dithizone, carminic acid and pyrocatechol violet dyes sensitized metal (Ho, Ba& Cd) doped TiO2/CdS nanocomposite as a photoanode in hybrid heterojunction solar cell

Considering the great importance of nanocomposite based photo-active nanomaterials for a variety of electronics, photonics and photovoltaics application, it is always worth considering to synthesize new hetreostructure. This paper describes the sol-gel and hydrothermal synthesis of metal (holmium, barium, and cadmium) doped TiO2/CdS nanocomposites for photoanode applications. Various characterization techniques, including XRD, FTIR, UV–VIS, EDX, and SEM were used to examine the synthesized heterostructures. The band gap of pure TiO2 NPs is 3.10 eV, which was effectively decreased to 2.16 eV by doping and coupling with CdS. The nanomaterial's crystallinity, crystallite size, morphology and elemental composition were determined by XRD, SEM and EDX, respectively. As sensitizers, the organic dyes dithizone, carminic acid, and pyrocatechol violet were used. FTIR was used to analyze the effective dye grafting on the surface of nanomaterials. In the presence of hole conducting P3HT polymer as solid state electrolyte, the sensitized materials were evaluated for solid state dye-sensitized solar cells. Compared to the reference device, Cd–TiO2/CdS photosensitized using Pyrocatechol violet dye demonstrated the highest efficiency of 2.68% (0.82%). Other parameters of this device, including open circuit voltage (Voc) and short circuit current (Jsc), were determined to be 16.97 mA cm2 and 0.41V, respectively.

Synthesis of polymer-gel electrolytes for quasi solid-state dye-sensitized solar cells and Modules: A potential photovoltaic technology for powering internet of things (IoTs) applications

Dye-sensitized solar cells can display brilliant performance in artificial/indoor light, predominantly in various wireless sensor networks applications. The main objective of this work was to fabricate stable dye-sensitized solar cells/modules for the internet of things applications. The stability issue was addressed by developing polymer gel electrolytes. Polymer gel electrolyte with the highest ionic conductivity value was then employed as an electron transport mediator in the cells and modules. The photovoltaic performance of cells was affected by the conductivity of electrolytes. The results showed that the efficiency of quasi-solid state dye-sensitized solar cells remained stable for a week, while the efficiency of conventional cells approached zero after a day. Thus, the development of polymer gel electrolytes is an ultimate solution to enhance the stability of dye-sensitized solar cells and modules for the internet of things applications.

Development of quasi solid state dye sensitized solar cells

Dye Sensitized Solar Cells (DSSCs) present a significant renewable energy source in terms of control of different parameters governing flexibility, efficiency, lifetime and cost. The liquid electrolytes used inside the cells are generally responsible for the leakage and inefficient encapsulation related issues. These are critical for practical applications of DSSCs. The choice of electrolyte medium used in the cell should take into account the fast regeneration of electrolyte and redox potential of the dye. Organic dyes in general, exhibit better extinction coefficients and variant color ranges. The present work is focused on quasi solid state DSSCs based on an organic dye. For the fabrication of devices, nanocrystalline titanium-di-oxide (TiO2) films were used as the photoanode and well known organic dye Eosin B as the sensitizer. The photovoltaic performance of the cells was measured at different light intensities. The results exhibited the quantum efficiency of organic dye Eosin B which can be used as a potential sensitizer in conjugation with quasi solid state electrolytes. Copyright © 2017 VBRI Press.

Synthesis of a carboxylic acid-based ruthenium sensitizer and its applicability towards Dye-Sensitized Solar Cells

This work reports the synthesis of ruthenium based Ru(bpy)2(dcbpy)(ClO4)2[(bpy)2,2′-bipyridine;dcbpy = 4,4′-dicarboxy-2,2′-bipyridine] (RuC) dye and its application in solid and liquid state Dye-Sensitized Solar Cells (DSSCs). Synthesis resulted with high-pure orange coloured dye with a high yield percentage of 45%. The dye was characterized via Nuclear Magnetic Resonance (NMR) spectroscopy, Mass spectroscopy, Cyclic Voltammetry (CV) and UV–vis spectroscopy. The calculated bandgap (Eg) of 2.38 eV from absorbance spectra of pure RuC in ethanol solution showed best proximity with the data obtained from CV measurements. The RuC showed strong absorption in near UV region with the highest molar extinction coefficient (MEC) of 14,746 M−1cm−1 at 463 nm. Plateau of over 80% of External Quantum Efficiency (EQE) spectra reveals the efficient carrier generation of RuC in near UV region. Carboxylic acid groups of RuC provide the potential for enhanced electron transfer from TiO2 surface, and an increased electron density at the interface leads to higher current density. The RuC sensitized solid and liquid state DSSCs exhibited a short circuit current density (JSC) over 3.04 mA/cm2 and 5.82 mA/cm2, and power conversion efficiency (PCE) of 1.2% and 1.8% respectively under simulated Air Mass 1.5 irradiation (100 mWcm−2).

High-efficiency quasi-solid state dye-sensitized solar cells using a polymer blend electrolyte with “polymer-in-salt” conduction characteristics

“Polymer-in-salt” electrolytes are special conductive materials that demonstrate much higher conductivity compared to the conventional “salt-in-polymer” electrolytes. However, up-to-now, they are found unsuitable for dye-sensitized solar cells (DSSCs) application, mainly because they lead to increased charge recombination rate. The present paper demonstrates the development and application in DSSCs of polymer blend electrolytes that utilize features found in “polymer-in-salt” electrolytes, while the aforementioned drawback is overcome. This is done with the appropriate selection and amount of polymers used to jellify the liquid state electrolyte, keeping the redox couple concentration fixed at a high level. Herein, the unique properties of polyvinylpyrrolidone (PVP), as a nitrogen-containing heterocyclic polymer, in combination with the ability of polyethylene glycol (PEG) to dissolve high quantities of ionic compounds, were the main reasons for developing PVP/PEG blend-based polymer electrolytes for DSSCs. The efficiency attained by the solar cells employing the polymer blend electrolytes was found enhanced up to 30% compared to the corresponding of DSSCs employing the PVP-based and PEG-based polymer electrolytes. By the extra use of two common additives in the best-performing polymer blend electrolyte and an advanced multi-layered photo-anode, the efficiency of DSSCs reached 8.21%, which is one of the highest reported for quasi-solid state DSSCs employing non-composite ionic liquid-free iodide-based polymer electrolytes. The results are also found quite satisfactory compared to the corresponding ones obtained by the DSSCs employing commercially available liquid state electrolytes, while the preparation of the proposed electrolytes is simple and of low-cost, and their composition has great prospects for further improvement.

PAN-Based Triblock Copolymers Tailor-Made by Reversible Addition–Fragmentation Chain Transfer Polymerization for High-Performance Quasi-Solid State Dye-Sensitized Solar Cells

For efficient polymer gel electrolytes (PGEs) in quasi-solid-state dye-sensitized solar cells (QSS-DSSCs), six ABA triblock copolymers based on (poly(acrylonitrile-co-N-(isobutoxymethyl)acrylamide)-block-poly(ethylene glycol)-poly(acrylonitrile-co-N-(isobuto-xymethyl)acrylamide)) (P(AN-co-BMAAm)-b-PEG-b-P(AN-co-BMAAm)) with various copolymer compositions and molecular weights, coded as SGT-605, SGT-606, SGT-608, SGT-609, SGT-611, and SGT-612, have been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization using PEG-functionalized macro-RAFT agents. The effects of copolymer compositions and molecular weights in P(AN-co-BMAAm)-b-PEG-b-P(AN-co-BMAAm) triblock copolymers were investigated in terms of electrochemical properties and photovoltaic performance as PGEs. The ionic conductivity was increased with N-(isobutoxymethyl)acrylamide (BMAAm) composition of these triblock copolymers, which is attributed to the availability of free iodide ions by complex formation among acrylamide groups with Li+ ions. However, polymer gel electrolytes with high molecular weights enhance ionic conductivity due to the lower amount of polymers required for the gel formation. Thus, the photovoltaic performances of PGE-based QSS-DSSCs improved along with the increase in the molecular weight of the triblock copolymer. The addition of 7 wt % TiO2 nanofiller into PGEs produced a higher ionic conductivity and diffusion of I3– than the corresponding PGEs. The resulting power conversion efficiency (PCE) of QSS-DSSCs using SGT-612/TiO2 composite PGEs under simulated 1-sun condition was 9.83% (Voc, 792.8 mV; Jsc, 16.65 mA/cm2; FF, 74.52%), which was higher than that of liquid electrolyte DSSCs (PCE 9.53%; Voc, 743.8 mV; Jsc, 17.16 mA/cm2; FF, 74.64%). The long-term device stability of PGE-based QSS-DSSCs was better than the liquid-state DSSCs.

A polyelectrolytic polyacetylene for quasi-solid state dye-sensitized solar cell applications

A new polyelectrolytic polyacetylene, poly(2-ethynyl-N-iodopyridinium triiodide), was applied for DSSCs. Poly(2-ethynyl-N-iodopyridinium triiodide) was prepared by the non-catalyst polymerization of 2-ethynylpyridine using iodine without any additional initiator or catalyst in high yields. The photoluminescence peak was observed at 534 nm corresponding to a photon energy of 2.32 eV. Quasi-solid-state DSSCs with a SnO2:F/TiO2/D719 dye/solid-state electrolyte/Pt device was fabricated with the poly(2-ethynyl-N-iodopyridinium triiodide) electrolyte, which shows the power conversion efficiency (PCE) of 5.79%.

Highly porous Ba3Ti4Nb4O21 perovskite nanofibers as photoanodes for quasi-solid state dye-sensitized solar cells

Ternary oxides are considered promising electrode materials for light harvesting devices due to their optical and electronic properties that can be tuned by controlling their composition and doping ratio. Herein, a facile approach is demonstrated to fabricate ternary oxide perovskite nanofibers (NFs) and their investigation investigated as efficient electrode materials in dye-sensitized solar cells (DSSCs). The fabricated electrospun hexagonal perovskite-like (A3B8O21) nanofibers are made of several small single crystals that are connected together to several micrometers in length. Upon sintering to 650 ⁰C, highly porous perovskite nanofibers were obtained, which increased the dye adsorption capacity of the nanofibers and in turn resulted in higher photoconversion efficiency than the traditional nanotubes counterparts. The crystallinity, chemical, and thermal characteristics of the fabricated NFs were investigated using XRD, SEM, TEM, and TGA analyses. Moreover, Brunauer–Emmett–Teller (BET) measurements were used to evaluate the effect of annealing temperature on the pore size and the overall surface area of the NFs. The fabricated nanofibers were used to construct full solar cell devices, revealing enhancement in the overall performance as indicated via the photocurrent-voltage curves. This enhancement is mainly related to the higher adsorption rate of the dye on the nanofibers surface. Highly porous electrospun nanofibers are good platforms that should be useful for the future development of solar cell devices.

A Simplest, Cheapest and Most Efficienct Technique to Enhance the Performance of Solid State Dye-Sensitized Solar Cell: Deposition of Purple Seaweed as a Photosensitizer

Solid state dye-sensitized solar cell (ss-DSSC) was developed to overcome the problem arise from electrolyte leakage in liquid state dye-sensitized solar cell. This work focused on the fabrication of ss-DSSC based on inorganic semiconductor of titania and organic conducting polymer of poly (3-hexylthiophene) (P3HT) and natural dyes from purple seaweed (PS dyes) via electrochemical, spin coating and dip coating method, respectively. The absorption spectrum and functional group of PS dyes were investigated using UV-Visible absorption spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy; respectively. Meanwhile, the effect of immersion time of PS dyes on performance of the device was studied via current density-voltage (J-V) characteristic. PS dye was absorbed in a wide range of solar spectrum in visible and near-IR region by chlorophyll a, phycocyanin and zeaxanthin pigments exists in the PS dyes. The present of carboxylic groups in PS dyes which bound to P3HT and formed P3HT-COOH enable the linkage to TiO2 surface which helps in the transfer of electrons from natural dyes to the conduction band of TiO2 film. The highest efficiency obtained was 1.44% at 10 minutes time of immersion. This concludes that PS dyes was a good photosensitizer and can be applied in ss-DSSC.

Anatase TiO2 Nanotubes-Aggregated Porous Microspheres for Ti Foil-Based Quasi-Solid State Dye-Sensitized Solar Cells with Improved Photovoltaic Performance

Fibrous anatase TiO2 nanotubes-aggregated porous microspheres (AMS) with high specific surface area (160 m2 g−1) were fabricated through an alkali solution-assisted hydrothermal process followed by an acid post-treatment and a calcination by using commercial TiO2 nanopowder (P25) as raw material. The resultant AMS microspheres with an average diameter of ~ 5 μm have three-dimensional network-like porous structures formed by accumulation and winding of fibrous TiO2 nanotubes with diameter < 10 nm. When used as photoanode materials of Ti foil-based quasi-solid state dye-sensitized solar cells, the AMS film-based solar cell gives a conversion efficiency of 7.16% with 34% improvement when compared to the P25 film-based one (5.34%).

Components control for high-voltage quasi-solid state dye-sensitized solar cells based on two-phase polymer gel electrolyte

For the quasi-solid-state electrolyte in dye-sensitized solar cells (DSSCs), the selection and optimization of components is a decisive process for high photovoltaic performance while maintaining stability. In this work, a two-phase polymer gel system based on PEO and PEGDME formed by chemical crosslinking is used as quasi-solid electrolyte in DSSCs. Through components of preparation solvent, iodine and GuSCN control, the photoelectric conversion efficiency of QS-DSSCs reaches 7.66%, especially the open-circuit voltage reaches 793 mV due to the self-assembly and ionic conductivity promotion. It lays a solid foundation for probing its potential value of quasi-solid dye-sensitized solar cells.

A Study on the effect of dye and polymer nanocomposite electrolyte on the performance of natural dye sensitized solar cells

Abstract Natural Dye sensitized solar cells (NDSSCs) are environmentally and economically remarkable than ruthenium-based dye sensitized solar cells because they are nontoxic and cheap. However, the photo conversion efficiency of dye-sensitized solar cells based on natural dye is low. One of the ways to improve the DSSC performance is enhancing the conductivity of electrolyte used. In this paper, we study the effect of polymer nanocomposite electrolyte consists of Polyvinylidene fluoride and poly(tetrahydrofuran) (PVdF/PTHF/EC/KI/I2) with three different ratios of nanofiller Manganese dioxide (n-MnO2). It was prepared by solution mixing method. The prepared polymer nanocomposite electrolyte were confirmed by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and ultraviolet–visible (UV-Vis) spectroscopic techniques. The surface morphology and particle size of prepared n- MnO2 and polymer nanocomposite electrolyte were studied using high resolution scanning electron microscopy (HRSEM) and X-ray diffraction (XRD). The ionic conductivity of polymer nanocomposite electrolyte was studied by electrochemical impedance spectroscopy (EIS). The natural quasi solid state dye-sensitized solar cell has been fabricated by using three different natural dye extracted from Beta vulgaris (beetroot), Hylocereus undatus (Dragon fruit) and Opuntia ficus-indica (prickly pear fruit) using PVdF/PTHF/EC/KI/I2/n-MnO2 polymer nanocomposite electrolyte. The photo conversion efficiency was measured and compared.

Performance of cross-linked polymers based gel electrolyte in the fabrication of quasi-solid state dye-sensitized solar cells

ABSTRACTCross-linked polymer (CLP) composed of poly(ethylene glycol) methyl ether acrylate and poly(ethylene glycol) diacrylate has been used in synthesizing gel electrolyte. A set of electrolyte samples was synthesized using gel casting method by varying the weight percentage ratio of cross-linked polymers from 2–14 % in an incremental order (2 %) with respect to poly (ethylene oxide) (PEO) and evaluated its performance by employing in the fabrication of dye-sensitized solar cells. The synthesized polymer was subjected to different analytical techniques such as NMR, TGA, DSC, GPC, and FTIR to confirm the materials. The molecular weight of the CLP has been measured using GPC and the obtained value is found to be 3.655 KDa with polydispersity of 1.94. The CLP-PEO gel electrolyte with 10 % weight ratio has obtained the highest ionic conductivity of 3.07 × 10−6 S/cm−1 at room temperature and best photo-conversion efficiency of 5.1 % was achieved for the same.

Iron and nickel doped tin (IV) oxide nanosheets: Synthesis, characterization and applications in hybrid solar cells

The pristine and (Fe and Ni)-doped tin (IV) oxide (SnO2) nanosheets were synthesized by hydrothermal method. These nanosheets were characterized in detail by UV- visible spectroscopy, fourier transform infra-red (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM revealed that the nanosheets varied in size from 14 nm to 40 nm. Electrical parameters such as resistance, resistivity and conductivity were also investigated by two probe resistivity measurements. Doped SnO2 nanosheets were found more conducting than pristine SnO2. The pristine and (Fe and Ni)-doped SnO2 nanosheets were used to fabricate photoactive blend for solid state dye-sensitized solar cells (DSSCs). The effects of pristine and (Fe and Ni)-doped SnO2 nanosheets on the efficiency of solar cells were investigated using photocurrent-voltage (J-V) measurements. Maximum power conversion efficiency of 0.48% was recorded for Ni-doped SnO2 nanosheets grafted with sulphonic acid functionalized dye. Other characteristic photovoltaic parameters were found as 2.54 mAcm−2, short circuit current density (Jsc), 0.42 mV, open circuit voltage (Voc) and 0.45, fill factor (FF). The band gap of SnO2 (3.8 eV) was significantly reduced to 3.2 eV and 2.8 eV for Fe and Ni-doped SnO2 respectively.

The Effect of Difference Molar Ratios of Dibromo-EDOT as Hole Transporting Material for Solid State Dye-Sensitized Solar Cells

The dye-sensitized solar cells (DSSCs) are one of the promising organic photovoltaic cells due to their low cost, flexibility, and relatively good efficiency. Nevertheless, utilization of liquid electrolyte in DSSCs brings practical problems for commercialization, which leads to solid-state dye-sensitized solar cells (ssDSSCs), that based on organic conducting polymers or inorganic p-type semiconductors as hole transport materials (HTM). A one-side ssDSSCs fabricated here, with a conductive polymer Dibromo-EDOT as an HTM, and also check ssDSSCs efficiency by variation of the HTM concentrations. The morphology of cells examined through SEM, and intensity-modulated photocurrent/voltage spectroscopy, measurements were used to elucidating the electrochemical properties of ssDSSCs. We also optimize the blocking layer thickness and different molar ratios of HTM for the best efficient ssDSSCs.

Ag2Se quantum dots for photovoltaic applications and ligand effects on device performance

In this paper, solid state dye-sensitized solar cells (DSSCs) with Ag2Se quantum dots (QDs) blocking layer are reported, three different bifunctional linker molecules such as mercaptopropionic acid (MPA), thioglycolic acid (TGA) and cysteine have been used to cap on TiO2 to link Ag2Se quantum dots. The linker molecule play a determinant role in well coverage loading of Ag2Se QDs and improve electron transport and recombination in device. The Ag2Se QDs can serve both as light absorber and charge blocking layer in device. The power conversion efficiency can be effectively enhanced and the highest one (4.38%) is achieved based on TiO2/cysteine/Ag2Se photoanode, showing 45% enhancement compared to that of the controlled one (3.03%).

Free-standing graphene/NiMoS paper as cathode for quasi-solid state dye-sensitized solar cells

Highly catalytic two dimensional and metal-doped two-dimensional nanomaterials (MoS2 and NiMoS) were deposited over free-standing graphene (FSG) paper using electrodeposition method and subsequently used as a counter electrode in quasi solid-state dye-sensitized solar cells (q-DSSCs). The replacement of FTO by FSG facilitates high electrical conductivity and electrodeposited metal sulphides provide electrocatalytic activity. The morphology, structural phase formation and chemical composition of FSG-MoS2 and FSG-NiMoS were investigated using FESEM, XRD, Raman and XPS analysis. The electrochemical behavior of metal sulphide decorated FSG cathodes is investigated using an electrochemical workstation and their effects on the photo-conversion efficiency of DSSCs were assessed. NiMoS with FSG substrate is an intriguing counter electrode material that can be utilized at low fabrication cost than the conventional platinum-based counter electrodes. FSG along with the metallic-two dimensional nanoparticles (NiMoS) functions as an effective catalytic material thereby allowing DSSCs to achieve enhanced efficiency of ∼7% to provide better alternative of FTO and Pt.

Solid state dye sensitized solar cells with polyaniline-thiourea based polymer electrolyte composition

The quest for cost effective and efficient solid-state electrolytes is a primary goal for dye sensitized solar cells (DSSCs). The present study describes an experimental approach of synthesizing simple composite electrolytes from iodide-triiodide ions (I−/I3−) incorporated into a polyaniline/thiourea matrix for solid-state DSSC applications. This electrolyte composition can be effectively used to decrease the probability of recombination at the TiO2/electrolyte interface and increase the catalytic process of I3− reduction at the electrolyte/counter electrode interface. The application of the optimized electrolyte in DSSC results in increased open-circuit voltage as well as short circuit current density, thereby increasing the overall efficiency by 73% as compared to the reference electrolyte. The present composition can prove to be a promising redox medium for solid state DSSCs.