Dye-sensitized Solar Cells Devices Research Articles

Graphene oxide doping in tropical almond (terminalia catappa L.) fruits extract mediated green synthesis of TiO2 nanoparticles for improved DSSC power conversion efficiency

The power conversion efficiency (PCE) of a dye-sensitized solar cell (DSSC) device depends on its semiconductor characteristics. Titanium dioxide (TiO2) nanoparticles are a semiconductor material commonly used in the DSSC device whose characteristics depend on the synthesis process. There are many routes to synthesize TiO2, however, they typically involve hazardous approaches, which may cause risk to the environment. Green synthesis is an environmentally friendly alternative method using ecological solvents that eliminates toxic waste and reduces energy consumption. In this work, tropical almond (Terminalia catappa L.) was used as a natural capping agent in the green synthesis to control the growth of TiO2. In addition, graphene oxide (GO) was used as a dopant to increase the performance of DSSC device. The results are convincing, in which the addition of 0.0017 % GO doping in tropical almond extract mediated green synthesis of TiO2 improved the PCE from 0.85 % to 1.72 %. These results suggest that GO-modified TiO2 nanoparticles green synthesized using tropical almond extract have great potential in the fabrication of DSSC devices with good PCE, low cost, and low environmental impact.

Effects of Several Auxiliary Acceptors and Anchoring Groups on Charge Transfer and Photophysical Properties of D-A-π-A Type DSSCs: A DFT Study.

In this paper, we performed theoretical studies on the twelve D-A-π-A type organic dyes (G-1 ~ G-3, M-1 ~ M-3, J-1 ~ J-3, and S-1 ~ S-3) with 9-phenylcarbazole as the electron donor in anticipation of the application of these dyes in dye-sensitized solar cells (DSSCs). DFT and TD-DFT methods are applied to investigate in detail the molecular geometries, frontier molecular orbitals (FMOs), absorption spectra, charge density difference (CDD), and transition density matrix (TDM) of several dyes. The results show that the M-series (M-1 ~ M-3) dyes have the largest dihedral angles between the electron donor and the auxiliary acceptor and also has the largest energy gaps in HOMO-LUMO orbitals, which greatly reduces the charge transfer efficiency. Finally, the UV-Vis absorption spectra inferred that the anchoring groups modified with o-nitrobenzoic acid (G-3, M-3, J-3, S-3) can red-shift the absorption peaks of the dyes, which results in higher light-harvesting efficiency and improves the power conversion efficiency of DSSCs. Overall, all of these dyes contribute to the improvement of photovoltaic power conversion efficiency and have potential for application in DSSCs devices.

Effect of Position of Donor Units and Alkyl Groups on Dye-Sensitized Solar Cell Device Performance: Indoline-Aniline Donor-Based Visible Light Active Unsymmetrical Squaraine Dyes.

Indoline (In) and aniline (An) donor-based visible light active unsymmetrical squaraine (SQ) dyes were synthesized for dye-sensitized solar cells (DSSCs), where the position of An and In units was changed with respect to the anchoring group (carboxylic acid) to have In-SQ-An-CO2H and An-SQ-In-CO2H sensitizers, AS1-AS5. Linear or branched alkyl groups were functionalized with the N atom of either In or An units to control the aggregation of the dyes on TiO2. AS1-AS5 exhibit an isomeric π-framework where the squaric acid unit is placed in the middle, where AS2 and AS5 dyes possess the anchoring group connected with the An donor, and AS1, AS3, and AS4 dyes having the anchoring group connected with the In donor. Hence, the conjugation between the middle squaric acid acceptor unit and the anchoring -CO2H group is short for AS2, AS5, and AK2 and longer for AS1, AS3, and AS4 dyes. AS dyes showed absorption between 501 and 535 nm with extinction coefficients of 1.46-1.61 × 105 M-1 cm-1. Further, the isomeric π-framework of An-SQ-In-CO2H and In-SQ-An-CO2H exhibited by means of changing the position of In and An units a bathochromic shift in the absorption properties of AS2 and AS5 compared to the AS1, AS3, and AS4 dyes. The DSSC device fabricated with the dyes contains short acceptor-anchoring group distance (AS2 and AS5) showed high photovoltaic performances compared to the dyes having longer distance (AS1, AS3, and AS4) with the iodolyte (I-/I3-) electrolyte. DSSC device efficiencies of 5.49, 6.34, 6.16, and 5.57% have been achieved for AS1, AS2, AS3, and AS4 dyes, respectively; without chenodeoxycholic acid (CDCA), small changes have been observed in the device performance of the AS dyes with CDCA. Significant changes have been noted in the DSSC parameters (open-circuit voltage VOC, short-circuit current JSC, fill factor ff, and efficiency η) for the AS5 dye while sensitized with CDCA and showed highest DSSC efficiency of 8.01% in the AS dye series. This study revealed the potential of shorter SQ acceptor-anchoring group distance over the longer one and the importance of alkyl groups on the overall DSSC device performance for the unsymmetrical squaraine dyes.

Highly Efficient DSSCs Sensitized Using NIR Responsive Bacteriopheophytine-a and Its Derivatives Extracted from Rhodobacter Sphaeroides Photobacteria.

Employing naturally extracted dyes and their derivatives as photosensitizers towards the construction of dye-sensitized solar cells (DSSCs) has been recently emerging for establishing sustainable energy conversion devices. In this present work, Rhodobacter Sphaeroides Photobacteria (Rh. Sphaeroides) was used as a natural source from which Bacteriopheophytine-a (Bhcl) dye was extracted. Further, two cationic derivatives of Bhcl, viz., Guanidino-bacteriopheophorbide-a (Gua-Bhcl) and (2-aminoethyl)triphenylphosphono-bacteriopheophorbide-a (2AETPPh-Bhcl) were synthesized. The thus obtained Bhcl, Gua-Bhcl and 2AETPPh-Bhcl were characterized using liquid chromatography-mass spectrometry (LC-MS) and their photophysical properties were investigated using excitation and emission studies. All three near-infrared (NIR) responsive dyes were employed as natural sensitizers towards the construction of DSSC devices, using platinum as a photocathode, dye-sensitized P25-TiO2 as a photoanode and I-/I3- as an electrolyte. DSSCs fabricated using all three dyes have shown reasonably good photovoltaic performance, among which 2AETPPh-Bhcl dye has shown a relatively higher power conversion efficiency (η) of 0.38% with a short circuit photocurrent density (JSC) of 1.03 mA cm-2. This could be attributed to the dye's natural optimal light absorption in the visible and NIR region and uniform dispersion through the electrostatic interaction of the cationic derivatives on the TiO2 photoanode. Furthermore, the atomic force microscopy studies and electrochemical investigations using cyclic voltammetry, electrochemical impedance spectroscopy and Bode's plot also supported the enhancement in performance attained with 2AETPPh-Bhcl dye.

Efficient processed carbon Soot@MoS2 hybrid Bi-functional electrode for dye-sensitized solar cell and asymmetric supercapacitor devices

A feasible approach to rectify the world's energy demand using sustainable development of adequate energy generation and storage technologies in a single channel. In this respect, we made a holistic approach with a bi-functional electrode material to perform effectively in energy generation and storage applications. MoS2 nanosheets were produced by the eco-friendly method and reduced graphene oxide is used to prepared by carbon soot which is derived from castor oil. The prepared soot and rGO were combined with MoS2 nanosheets using a simple sonication method. The as-prepared sample was introduced in the supercapacitor and DSSC application. The combination MoS2@rGO provides an enhanced conversion efficiency of 11.81 ​% and the reproducibility of DSSC is also studied. Further, MoS2@rGO is used to fabricate an asymmetric supercapacitor to investigate its real-time application. The device produced the maximum power density (1666.6 ​mW/kg) and energy density (25.69 ​mWh/Kg) at 1 A/g. The asymmetric supercapacitor device holds a cyclic stability of 81.4 % for 5000 cycles and it powered up an LED device for 4 ​min.

The brief study of ZnO/PEDOT:PSS counter electrode in DSSC Based on solid electrolyte YSZ

Dye-Sensitized Solar Cell (DSSC) is a photovoltaic technology that is eco-friendly, has affordable costs, an easy fabrication process, and high power conversion efficiency. The application of solid electrolytes in DSSC is a promising option compared to using liquid electrolytes because liquid electrolytes easily cause corrosion on the photoanode and counter electrode. The role of the counter electrode in DSSC is crucial to speed up the electron transfer process to enhance the performance of DSSC devices. Much research on DSSC still uses a lot of platinum and graphene which are relatively expensive and supplies are limited. Therefore, this research will develop a low-cost and easy to fabricate counter electrode made of ZnO/PEDOT:PSS composite. Adding ZnO in PEDOT:PSS polymer can obtain higher catalytic activity, that can accelerate oxidation–reduction reactions to improve the performance of DSSC solar cells. From the results of this study, it can be concluded that the addition of ZnO mass to the ZnO/PEDOT: PSS composite can increase lattice parameters, crystal size, porosity values, and light absorbance. Based on the I-V testing, it shows that the addition of ZnO mass to the ZnO/PEDOT:PSS composite results in the highest efficiency of 3.29%.

Quantum Chemical Studies of Sensitizers Designed for Dye-Sensitive Solar Cells

In this study, two different organic dyes with a D-π1-R-π2-A structure were designed from the reference dye E0 with a D-π1-π2-A structure (E3-E4). By adding 2,3-dicyanopyrirazinophenanthrene between the π-bridges on the reference dye E0 and changing the π-bridge, dyes designed to examine the photovoltaic features for use in dye-sensitized solar cell (DSSC) devices were obtained. Various properties of the designed dyes, such as their geometrical structures, absorption spectra, nonlinear optical properties (NLOs), energy levels, boundary molecular orbitals, and some photovoltaic and chemical reactivity parameters, were investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to improve the performance of Dye-Sensitized Solar Cells (DSSCs). The calculated theoretical results concluded that E4 of the designed dyes can have a high short-circuit current and better power conversion energy (PCE) compared with E0. These results indicate that adding different auxiliary ligands and modifying the π-bridges can effectively improve the photovoltaic performance of the system.

Synthesis of ZnO-TiO2 Nanoparticles by Sol-Gel Process and its Application for Solar Cell Semiconductor

ZnO-TiO2 semiconductor can be used in Dye-Sensitized Solar Cell (DSSC) devices as an alternative to renewable energy. This semiconductor can be synthesized by sol-gel method. The objective of this study is synthesizing the TiO2-doped ZnO nanoparticle semiconductors for DSSC devices with mangosteen peel extract dye. Avocado seeds were extracted with water, as a capping agent in the synthesis of ZnO-TiO2 (TiO2 ratio of 0,3,5,7 and 10% to ZnO). XRD results show the success of ZnO-TiO2 doping, due to the 2θ shift and changes in the crystal lattice. The average crystal size obtained was 33.7972 nm. The SEM results showed that the particle size of ZnO ranged from 45-100 nm. The UV-Vis dye measurements of mangosteen peel extract showed an absorption peak at 296-483 nm wavelength, with a corresponding band gap energy value of 3.04 eV. The UV-Vis DRS ZnO-TiO2 measurements have an average band gap energy of 3.1425 eV and ZnOof 3.1915 eV. The highest DSSC efficiency value is 2.15 x 10-2% at 7% ZnO-TiO2 semiconductor.

NiSe2-CoSe2 hollow polyhedron as counter electrode catalyst for high-efficiency dye-sensitized solar cells

The design of efficient counter electrode (CE) materials for dye sensitized solar cells (DSSCs) strongly depend on the microstructure construction and the effective combination of different active components. In this study, a hollow polyhedral structured NiSe2-CoSe2 composite electrode was synthesized through the direct selenization of the hollow nanocage morphology nickel-cobalt layered double hydroxide (NiCo-LDH) ultrathin nanosheets, which was derived from ZIF-67 nanocrystals. Notably, owing to the unique hollow structure and synergistic effect of the Ni-Co bimetallic selenides, the hollow polyhedral NiSe2-CoSe2 CE exhibited the expected electrochemical catalytic activity in the reduction of triiodide, as revealed by electrochemical impedance spectroscopy, cyclic voltammetry and Tafel polarization measurements. The photovoltaic results revealed that the PCE of the NiSe2-CoSe2 CE reached 8.21 %, which was higher than those of the Pt and CoSe2 CEs (7.62 % and 6.78 %, respectively). Moreover, the hollow NiSe2-CoSe2 CE exhibited a favourable photocurrent response upon light on-and-off cycling and improved stability over multiple start. This study provides a meaningful reference for the construction of hollow polymetallic transition-metal selenides for DSSC devices.

Visible-Light-Active Unsymmetrical Squaraine Dyes with Pyridyl Anchoring Groups for Dye-Sensitized Solar Cells.

Visible-light-active alkyl group-wrapped unsymmetrical squaraine dyes SD1-SD3 were synthesized, featuring an indoline donor and pyridine and carboxylic acid anchoring groups. Their photophysical, electrochemical, and photovoltaic characteristics were examined by fabricating a dye-sensitized solar cell (DSSC) device. Both carboxylic acid and pyridine anchoring groups containing squaraine dyes SD3 and SD2 possess similar photophysical and electrochemical characteristics. However, their photovoltaic performances were completely different. The SD3 dye with the carboxylic acid anchoring group displayed a DSSC device efficiency of 7.20% (VOC 0.81 V; JSC 12.29 mA/cm2) using iodolyte (I-/I3-) electrolyte, compared to SD1 (VOC 0.659 V; JSC 4.97 mA/cm2; and η - 2.34%) and SD2 (VOC 0.629 V; JSC 1.68 mA/cm2; and η - 0.84%), which were featured with pyridyl anchoring groups. These results were attributed to dye loading on the Lewis and Brønsted acidic sites of TiO2 and the importance of aggregated structures for photocurrent generation. In the incident photon-to-current efficiency (IPCE) analysis, SD1 dye-sensitized devices exhibited photocurrent generation from both monomeric and aggregated dyes on the TiO2 surface. In contrast, SD2 showed photocurrent generation solely from aggregated states. Despite the introduction of long alkyl chains to reduce dye aggregation and charge recombination, the results indicated preferential charge injection from only the aggregated SD2 dye on TiO2. Fluorescence-quenching experiments indicated an efficient charge transfer from the aggregated SD2 dye to TiO2 compared to that of the monomeric dye. Cosensitization, a method to enhance the light-harvesting efficiency and photocurrent generation in DSSCs, was explored by simultaneously cosensitizing pyridyl-based dyes (SD1 and SD2) with a blue-colored carboxylic acid-based squaraine dye SD4. IPCE analysis demonstrated that both SD1 and SD4 contributed to generating a photocurrent of 9.11 mA/cm2. The sequential cosensitization of SD1 and SD4 with the coadsorbent CDCA showed the highest performance, with a VOC of 0.663 V, a JSC of 11.43 mA/cm2, and an efficiency (η) of 5.20%.

Preparations of MgO Nanoparticles by a Poly(acrylic acid)s Template-Assisted Method and Photovoltaic Performances of Dye-Sensitized Solar Cells based on MgO lnterlayer.

Magnesium oxide (MgO) nanoparticles are commonly used to enhance the reactivity and performance of devices and systems in various applications, primarily due to the heat-resistance, binding, and alkaline properties of MgO. However, most of the methods used to synthesize MgO nanoparticles suffer from nonuniform particle size distributions that make it difficult to manufacture stable particles. In this study, uniform magnesium oxide (MgO) nanoparticles were developed for TiO2 photoelectrodes of dye-sensitized solar cells (DSSCs) to enhance their interfacial resistances. The uniform MgO nanoparticles were synthesized from MgO 93% using a poly(acrylic acid) template-assisted method. The particle size and crystalline structure of MgO nanoparticles were characterized by NANOPHOX particle size analysis, transmission electron microscopy, and X-ray diffraction. Multilayered TiO2 photoelectrodes containing interlayers of MgO nanoparticles were fabricated as photoelectrodes for DSSC devices, and their photovoltaic performances were investigated. When the MgO interlayer was introduced into the multilayered TiO2 photoelectrode, it not only increased the photocurrent value of the DSSC device but also improved its power conversion efficiency. The DSSC device containing the MgO interlayer and the scattering layer exhibited an open-circuit voltage of 0.74 V, a short-circuit current density of 14.60 mA/cm2, and a fill factor of 0.64 under a photointensity of 100 mW/cm2 at AM 1.5, resulting in an overall solar energy conversion efficiency of 6.94%. The application of an MgO interlayer in a DSSC device exhibited improved conductivity, charge transfer ability, and excellent device performance.

Aniline and Indoline Donors Based Far‐Red Active Unsymmetrical Squaraine Dyes for Dye Sensitized Solar Cells

AbstractIn dye‐sensitized solar cells (DSSC), controlling the dye‐aggregation on the metal‐oxide surface by appending the alkyl groups around the donor or π‐spacer unit of the dye is a potential approach to enhance DSSC efficiency. Further, rigidification of the dye structures by cyclization modulates the photophysical properties of the sensitizer. Here a series of donor‐acceptor‐donor (D‐A‐D) type far‐red active unsymmetrical squaraine dyes (SQA) have been designed and synthesized, where N,N‐dimethylaniline, methylated‐ and branched‐indoline have been used as donor units. These dyes showed absorption between 629–654 nm (λmax) with the molar extinction coefficient of 1.49–1.94×105 M−1 cm−1. Systematic enhancements in DSSC device efficiency have been observed due to the cyclization and alkyl‐groups incorporation in this set of dyes which were further enhanced with the addition of chenodeoxycholic acid (CDCA). The highest DSSC device efficiency of 4.78 % (Jsc of 8.77 mA/cm2 and Voc of 692 mV) has been achieved for SQA3. The IPCE profile of SQA dyes indicates the contribution of aggregated structures for the photocurrent generation. Further, co‐sensitization of SQA3 dye with a complementary visible light active dye AK4 showed the enhanced device efficiency of 6.27 % with panchromatic IPCE response.

Investigation of the effect of a nitro group as an anchor group in dye-sensitized solar cells

As a result of the increasing in the world population, the development of technology to meet increasing energy needs and to find other energy resources is one of the biggest tests for society. Triphenylamine and its derivatives attract the attention of researchers due to their many applications such as in solar cells, electronics, and medicine. The nitro group, an electron-accepting chromophore, is a good candidate for D–π–A sensitizers for dye-sensitized solar cells. In this study, the power conversion efficiency of an anchor nitro group in dye-sensitized solar cells and the synthesis of new compounds containing a donor triphenylamine unit, functionalized with a nitro group as an anchor group and possessing a π-conjugated structure are investigated. The structures of the compounds are determined by FTIR, UV-Vis spectrometry, NMR, and MS. Considering the photovoltaic performance of the produced dye-sensitized solar cell devices, the anchor group, and its acceptor effect, it is observed that the efficiency increases, in the order, F2 < F1. The highest power conversion efficiency value of 0.45% was obtained with the F1-based dye-sensitized solar cell under amplitude modulation irradiation (100 mW cm−2). From the obtained results, it can be seen that an increase in the number of electron-donor groups located close to the anchor group increases the power conversion efficiency.

A new push–pull dye for semi-transparent p-type dye-sensitized solar cells: Tuning conjugation by sexithiophene chain engineering

We report on the synthesis of two new dyes to be employed as sensitizers in p-type dye-sensitized solar cells (DSCs). The design of the two new molecules under consideration has been inspired by the state-of-art dye PMI-6 T-TPA. In particular, a specific engineering of the thiophene-based central core is here considered to favour structural planarity between an oligothiophenic π-spacer (a sexithiophene), and the acceptor and donor units made by peryleneimide (PMI) and triphenylamine (TPA) moieties, respectively. This leads to a wide absorption in the NIR with stabilization of the HOMO energy level in the resulting dyes, as supported by TD-DFT simulations and spectroscopic characterization. When tested as sensitizers in NiOx-based p-type DSCs, A6D (with an Acceptor-π-Donor structure) outperforms both its counterpart with a Donor-π-Donor structure (D6D) and P1, a benchmark dye in the field of p-DSCs. With A6D dye-sensitizer the resulting DSC device presents the quite remarkable value of stabilized efficiency as high as 0.15 % when I-/I3- is employed as redox couple and nanostructured NiOx photocathode is thick less than 2 μm and does not contain any blocking layer. Notwithstanding the panchromatic feature of the sensitizer, A6D-based devices show an average visible transmittance (AVT) of 8 %. Such a result paves the way toward the application of these types of multifunctional dyes in semi-transparent solar cells.

2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene)malononitrile functionalized diketopyrrolopyrrole: Synthesis and solar cell applications

Diketopyrrolopyrrole (DPP) functionalized with 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene) malononitrile (TCF) material coined as DPP-TCF was designed and synthesized. DPP-TCF exhibited strong absorption bands in solution as well as thin-film form. Herein, we report construction of dye sensitized solar cells (DSSCs) based on DPP-TCF anchored on CdS nanowires (NWs) coated on fluorine doped tin oxide (FTO) coated glass substrate with the device architecture FTO/CdS compact/CdS nanowire/DPP-TCF chromophore/electrolyte/ platinum coated FTO. As-fabricated DSSC device based on DPP-TCF and CdS nanowires exhibited power conversion efficiency (η) of 0.427%. Thus, the present work successfully displayed the utilization of DPP-TCF as an efficient light harvester in DSSC applications. This approach can also be employed to design and development of other DPP based organic molecular chromophores for DSSC applications.

Visible light photoredox catalysis for the synthesis of new chromophores as co-sensitizers with benchmark N719 for highly efficient DSSCs

Dye-sensitized solar cells (DSSCs) are becoming increasingly popular as low-cost organic photovoltaic devices due to their ease of fabrication and affordability. However, a primary limitation of DSSCs is their inability to absorb the entire solar spectrum, leading to lower efficiency. To overcome this limitation, a study was conducted to investigate the use of co-sensitization with two dyes that absorb different wavelengths of light to enhance the overall light absorption. In this study, four novel donor-acceptor (D-A) dyes (5a-d) containing benzo-1,4-diazine or benzo-1,4-oxazine groups as donors and a carbonyl group as an anchor were synthesized using a green and sustainable method to be used as co-sensitizers in DSSCs. These photosensitizers were co-sensitized with the Ru(II) dye N719 and were observed to significantly improve the light-harvesting ability of the device. The co-sensitizers (5a-d) reduced charge recombination, inhibiting dye aggregation, and increased dye loading on the TiO2 photoanode, leading to improve the overall device performance because of the appropriate molecular volume structures of (5a-d), which can fill the adsorption gap between N719 dye. The DSSC device of N719 showed a power conversion efficiency (PCE) of 7.81 % (JSC = 19.06 mA cm−2, VOC = 0.65 V, and FF = 61.24%). After co-sensitization, the PCE and short-circuit current of the device were significantly improved to reach (PCE = 8.79, JSC = 22.89 mA cm−2 and VOC = 0.68 V for 5a), (PCE = 8.56%, JSC = 22.37 mA cm−2, and VOC = 0.68 V mA cm−2 for 5b), (PCE = 8.59%, JSC = 22.45 mA cm−2, and VOC = 0.67 V for 5c) and (PCE = 8.50%, JSC = 21.93 mA cm−2, and VOC = 0.67 V for 5d). These findings demonstrate that co-sensitization with these novel dyes can compensate for the absorption defects of the Ru(II) dye and suppress charge recombination, leading to enhanced overall PCE in DSSCs.

Exploring DSSC Efficiency Enhancement: SQI-F and SQI-Cl Dyes with Iodolyte Electrolytes and CDCA Optimization.

This investigation delves into the potential use of halogen bonding to enhance both the short-circuit current (JSC) and overall efficiency of dye-sensitized solar cells (DSSCs). Specifically, we synthesized two distinct dyes, SQI-F and SQI-Cl, and characterized them using FT-IR, 1HNMR, 13C NMR, and mass spectroscopy. These dyes are based on the concept of incorporating halogen atoms within unsymmetrical squaraine structures with a donor-acceptor-donor (D-A-D) configuration. This strategic design aims to achieve optimal performance within DSSCs. We conducted comprehensive assessments using DSSC devices and integrated these synthesized dyes with iodolyte electrolytes, denoted as Z-50 and Z-100. Further enhancements were achieved through the addition of CDCA. Remarkably, in the absence of CDCA, both SQI-F and SQI-Cl dyes displayed distinct photovoltaic characteristics. However, through sensitization with three equivalents of CDCA, a significant improvement in performance became evident. The peak of performance was reached with the SQI-F dye, sensitized with three equivalents of CDCA, and paired with iodolyte Z-100. This combination yielded an impressive DSSC device efficiency of 6.74%, an open-circuit voltage (VOC) of 0.694 V, and a current density (JSC) of 13.67 mA/cm2. This substantial improvement in performance can primarily be attributed to the presence of a σ-hole, which facilitates a robust interaction between the electrolyte and the dyes anchored on the TiO2 substrate. This interaction optimizes the critical dye regeneration process within the DSSCs, ultimately leading to the observed enhancement in efficiency.

Benzothiazole functionalized diketopyrrolopyrrole photosensitizer for CdS nanowire based DSSC applications

Although dye sensitized solar cell (DSSC) make promising progress for solar energy conversion to electrical energy, there are still great need for further research work to develop an efficient sensitizer with a simple synthetic protocol. In this study, two chromophores (E)-2-(benzo[d]thiazol-2-yl)-3-(5-(2,5-bis(2-ethylhexyl)-3,6-dioxo-4-(thiophen-2-yl)-2,3,5,6-tetrahydropyrrolo[3,4-c]pyrrol-1-yl)thiophen-2-yl)acrylonitrile (DPP-BTH1) and 3-(5-(2,2-bis(benzo[d]thiazol-2-yl)vinyl)thiophen-2-yl)-2,5-bis(2-ethylhexyl)-6-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP-BTH2) are developed with broad range of absorption. The benzothiazole subunit 2-(benzo[d]thiazol-2-yl)acetonitrile (BTH1) and bis(benzo[d]thiazol-2-yl)methane (BTH2) auxiliary subunits were incorporated at the 5-(2,5-bis(2-ethylhexyl)-3,6-dioxo-4-(thiophen-2-yl)-2,3,5,6-tetrahydropyrrolo[3,4-c]pyrrol-1-yl) thiophene-2-carbaldehyde (DPP) core. DSSC devices with DPP-BTH1/CdS and DPP-BTH2/CdS nanowire photoelectrode under AM 1.5 G sun illumination exhibited power conversion efficiency of about 0.30 % and 0.45 %, respectively. The PCE is three and four-fold higher than that of bare CdS nanowire-based DSSC devices. These simple chromophores provide a promising perspective for next-generation photovoltaic devices to harvest sunlight efficiently.

Glycerol-supportive Y3+ infused TiO2 nanoparticles: An electrode material for dye sensitized solar cell and supercapacitor applications

The present research objective is to synthesize an active electrode material for dual application of dye sensitized solar cells (DSSCs) and supercapacitors (SCs). In this study, aliovalent rare earth yttrium doped TiO2 nanomaterial with three different dopant concentration (1, 3 and 5 mol%) were synthesized in green synthesis approach employing solvothermal method using glycerol as a ligand and structure directing agent. Fabricated DSSC device with 5 mol% yttrium doped TiO2 as photoanode exhibited the maximum power conversion efficiency of 6.88% with Voc of 0.715 V, Jsc of 15.27 mA/cm2 and FF of 63.01%, when compared to other devices fabricated using photoanodes of pure TiO2, 1 and 3 mol% Y doped TiO2. Likewise for supercapacitor application, the specific capacitance of 5 mol% Y-TiO2 nanoparticles based working electrode studied from Cyclic Voltammetry analysis was 858.04 F/g at a scan rate of 10 mV/s and from Galvanostatic Charging Discharging analysis it was 346.67 F/g at a current density of 1 A/g. Furthermore, 5 mol% Y-TiO2 nanoparticles exhibited better cyclic stability and retained 84.01% efficiency of its initial specific capacitance even after 1000 cycles at 3 A/g. The electrochemical measurements show that 5 mol% Y-TiO2 nanoparticles have 95.7% coulombic efficiency. This research endeavor paves the way for the green synthesis of nanomaterials that can be utilized to fabricate electrodes of devices for energy conversion and storage application.

Significance of anchoring group design on light harvesting efficiency of dye-sensitized solar cells and non-linear optical response

Dye-sensitizers designed from coumarin backbone are widely utilized in solar light harvesting due to their versatile performance in dye-sensitized solar cells (DSSC). They are well-known as non-linear optical (NLO) materials. In this case study, we have designed coumarin-based sensitizers containing thiophene as a common spacer with the different acceptor-anchoring groups, ethyl-2-cyanoacrylate (SPDSSC 1) and 2-cyanoacrylic acid (SPDSSC 2). Density functional theory (DFT) and time-dependent- DFT (TD-DFT) computational calculations of these molecules predict superior light harvesting capability and NLO properties. The calculated HOMO–LUMO energy gap of these dyes showed an inverse relation with chemical potential and electrophilicity index and was directly related to hardness and hyperhardness. It was also seen β0 and γ and PCE follow a similar trend. Further, computations of sensitizers@TiO2 indicated sensitizers with ethyl-2-cyanoacrylate bonded with TiO2 cluster via unidentate linkage, whereas 2-cyanoacrylic acid containing sensitizer involved bidentate bonding with TiO2. Apart from this, sensitizers with 2-cyanoacrylic acid anchors showed much planer geometry. Also, the quantitative analysis of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) and MEP plots showed that more electron clouds shifted to the TiO2 cluster in the sensitizer with 2-cyanoacrylic acid (SPDSSC 2) than ethyl-2-cyanoacrylate (SPDSSC 1). Further, both molecules were taken as sensitizers in the DSSC device. SPDSSC 2 showed higher power conversion efficiency than SPDSSC 1. Overall, results disclosed that sensitizers with ethyl-2-cyanoacrylate having two oxygen atoms in their anchoring part could bind with only carbonyl oxygen. And this monodentate binding of ethyl-2-cyanoacrylate with TiO2 leads to poor charge transfer in the semiconductor's conduction band, resulting in poor DSSC performance.