Photosensitizers For Dye-sensitized Solar Cells Research Articles

Comparative characterizations of plant and mineral dye as potential photosensitizer in Dye-Sensitized Solar Cell

The advent of dye-sensitized solar cells (DSSC) has expansively seen more studies as an alternative to silicon-based and thin-film solar cells due to their simple structure and relatively low production cost. In dye-sensitized solar cells, the dye is one of the major components for high power conversion efficiencies. The extracted dyes were characterized by powder x-ray diffraction, x-ray fluorescence, Scanning electron microscopy, UV-visible spectroscopy, and Gas Chromatography-Mass spectrometry analysis. The structure of the mineral dye contains constituents that enhance better absorption of solar radiation for use in a Dye-Sensitized Solar Cell (DSSC). The calcium and iron content of the mineral dye studied as revealed by the mineralogical analysis done using the powder x-ray diffraction (XRD) and the x-ray fluorescence (XRF) suggest this. These metals serve as bounding complexes to other organic components in the dye, like in the case of Ruthenium complexes dye for efficient absorption of solar radiation, especially in the visible light region. The functional groups present in the dye also confirm what favors good absorption of solar radiation for DSSC application. The Organic chemical compositions present in the mineral dye which were obtained by the Gas Chromatography-Mass spectrometry analysis also confirm the functional groups of carbonyl, Amine, and hydroxyl revealed by FTIR, which were responsible for solar radiation absorption. There are strong absorption narrow bands in the visible region with peaks at around 424 nm (2.903 a.u) and 486 nm (2.973 a.u). Optical band gaps of 1.66 eV and 2.27 eV for the mineral dye and plant dye respectively, were obtained. The properties of the dyes studied give potential substitutes to the relatively expensive ruthenium-based dyes for use in DSSC fabrication.

Theoretical exploration of a di-carbazole based dye for 3rd generation dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are known for their large potential in green, efficient and cost-effective solar energy technology. Therefore, investigating the solar-to-electricity conversion mechanism of photosensitizers in DSSCs can open up a new way for highly effective and stable solar cell devices. In this study, we used different molecular design strategies to develop various D-π-A photosensitizers based on dicarbazole. These approaches involved changing the positions of auxiliary acceptors and π-spacers as well as introducing new π-spacer units. To calculate the physical and electronic properties of these sensitizers, density functional theory (DFT) and time dependent density functional theory (TDDFT) were adopted. FMO analysis showed a significant charge transfer from the donor through the spacer to the acceptor which was also supported by DOS analysis. Energy gap of designed dyes have less than experimental Cz dye. NBO analysis has carried out the bond strength assessment and the studied molecule’s central nitrogen atoms related MOs. All the designed dyes exhibited good nonlinear optical (NLO) properties with maximum linear polarizability 〈α〉 amplitudes higher than first (βtotal) compared to the reference chromophore. Photovoltaic efficiency has been evaluated to electronic (Egap), open circuit voltage (VOC), short circuit current density (JSC), electron injection ability (∆Ginj), electron regeneration (∆Greg) and light harvesting efficiency.

Polymers Containing Phenothiazine, Either as a Dopant or as Part of Their Structure, for Dye-Sensitized and Bulk Heterojunction Solar Cells.

Potential photovoltaic technology includes the newly developed dye-sensitized solar cells (DSSCs) and bulk heterojunction (BHJ) solar cells. Owing to their diverse qualities, polymers can be employed in third-generation photovoltaic cells to specifically alter their device elements and frameworks. Polymers containing phenothiazine, either as a part of their structure or as a dopant, are easy and economical to synthesize, are soluble in common organic solvents, and have the potential to acquire desired electrochemical and photophysical properties by mere tuning of their chemical structures. Such polymers have therefore been used either as photosensitizers in dye-sensitized solar cells, where they have produced power conversion efficiency (PCE) values as high as 5.30%, or as donor or acceptor materials in bulk heterojunction solar cells. Furthermore, they have been employed to prepare liquid-free polymer electrolytes for dye-sensitized and bulk heterojunction solar cells, producing a PCE of 8.5% in the case of DSSCs. This paper reviews and analyzes almost all research works published to date on phenothiazine-based polymers and their uses in dye-sensitized and bulk heterojunction solar cells. The impacts of their structure and molecular weight and the amount when used as a dopant in other polymers on the absorption, photoluminescence, energy levels of frontier orbitals, and, finally, photovoltaic parameters are reviewed. The advantages of phenothiazine polymers for solar cells, the difficulties in their actual implementation and potential remedies are also evaluated.

Chemical structure modification of Brazilin-based natural dye with TiO2 nanostructure improves photovoltaic properties for maximum simulated PCE for DSSCs application

Brazilin has been explored as a photosensitizer in dye-sensitized solar cells (DSSCs) owing to its easy extraction, abundance, and environmental friendliness. However, its narrow solar spectrum absorption and weak interaction with the semiconductor hamper its wide application, highlighting the need for developing novel dyes for enhanced DSSC performance. This study reports eight designed dyes (Braz 01 ‒ Braz 02tb) obtained via introducing the π-bridges such as benzene, thiophene, and benzene-thiophene linked to thieno[3,2-b]thiophene, alongside a cyanoacrylic acceptor into the sites of two hydroxyl (OH) groups of brazilin dye. The density functional theory (DFT) and time-dependent density functional theory (TD- DFT) methods were employed to examine the free dyes' photoelectrical, optoelectronic and structural properties. The results show that the absorption spectra of the designed dyes redshifted by 183.22 nm 239.43 nm regarding the brazilin dye. The energy gap was reduced from 5.074 to 2.46 eV. The reorganization energy decreased from 0.951 eV to 0.528 eV, indicating that the designed dyes exhibited better intramolecular charge transfer (ICT). Notably, the electron affinity, electron accepting power, and maximum charge transfer increased from 1.021 3.472 eV, 1.024 8.387 eV and 1.447 4.780, respectively, signifying improved ICT. The exciton binding energy was lowered from 0.591 0.137 eV, implying that all designed dyes possess minimum charge recombination. The amount of charge transfer of the designed dyes (0.286219.051 au) was observed to be greater than brazilin, signifying enhanced ICT. Moreover, the theoretical DSSCs sensitized with designed dyes demonstrated higher PCE than brazilin dye. The greatest PCE of 13.1 % was attained by Braz 01tb dye. Generally, the improved optoelectronic and photovoltaic characteristics observed in all the designed dyes indicate that modifying the hydroxyl group on the brazilin's R1 or R2 location enhances its photoelectrical properties. Therefore, the designed dyes are regarded as superior candidates for utilization as photosensitizers in DSSCs.

Synthesis and characterization of new purple and green heterocyclic dyes for dye-sensitized solar cells

Due to the growing demand for energy from industrial activities, solar energy has gained increasing attention globally. In recent years, heterocyclic dyes have gained attention due to their potential use as organic photosensitizers in dye-sensitized solar cells (DSSCs). To develop new and effective synthetic dyes for DSSCs, a study was conducted to create new purple dyes 8-(4-chlorophenyl)-5-(hydroxyimino)-3H-imidazo[4′,5′:3,4]benzo[1,2-c]isoxazol-4(5H)-ylidene)-2-arylacetonitriles. These dyes were synthesized by reacting nitro derivatives of imidazo benzoxazole with arylacetonitriles in an alkaline media. Additionally, new fluorescent heterocyclic systems 3-(4-chlorophenyl)-6H-imidazo[4,5-a]isoxazolo[4,3-c]acridine-7-carbonitriles were obtained by heterocyclization of the purple dyes with SOCl2. The highest yield achieved in the synthesis of the title dyes is 74 %. The structures of the new purple and green heterocyclic dyes were confirmed through elemental analysis and spectroscopic data. The photophysical properties of the dyes were investigated using a UV–visible spectrophotometer and a fluorophotometer. The electrochemical characteristics of the purple dyes and fluorescent heterocyclic systems were also studied using cyclic voltammetry. The geometries of the dyes, as well as their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, were determined through theoretical calculations using density functional theory (DFT). Furthermore, the photovoltaic performance parameters of the new dyes were examined by analyzing their incident photon-to-current efficiency (IPCE) spectra and current-voltage (I-V) curves. The experimental results showed that the purple dyes exhibited remarkable photovoltaic performances, up to 6.55 %.

A DFT and TD-DFT studies of the photosensitizing capabilities of thiophene-based dyes

Dye-sensitized solar cells (DSSCs) play a significant role in the development of affordable, safe, and efficient solar energy technology. In this research, we have designed nine new dyes (J01-09) by modifying an experimentally reported thiophene-based dye (DSS) in the literature. The diethylaniline in the DSS as the electron donating group was replaced with diphenylamine to reduce planarity in the dye. The designed dyes all have donor and acceptor groups linked by a π-linker group (D-π-A). Using DFT and TD-DFT, we investigated the impact of the diphenylamine moieties on the planarity, photochemical and photophysical properties of the modeled dyes in isolation. The optimized structures, UV–Vis absorption, photochemical, and photovoltaic parameters were computed to study the photosensitizing capability of the modeled dyes. The photochemical and photovoltaic parameters of the study include; open-circuit voltage (VOC), light-harvesting efficiency (LHE), driving force of electron injection (ΔGinj), driving force of regeneration (ΔGreg), excited-state lifetime (τ), ionization potential (IP), adiabatic ionization potential (AIP), vertical ionization potential (VIP), electron affinity (EA), chemical hardness (η), electrophilicity index (ω), electron-donating power (ω-) and electron-accepting power (ω+) were calculated. Our findings indicate that only J03 and J08 absorb at longer wavelengths (719 and 753 nm respectively) indicating lower absorption energy bandgap compared to the DSS dye, attributed to the extension of conjugation between the thiophene and donor groups. Also, only J03 and J08 exhibited lower ΔGinj values (−0.985 and −0.667 eV respectively) and ΔGreg values (0.245 and 0.179 eV respectively) implying the dyes can be regenerated spontaneously compared to the DSS dye. Therefore, J03 and J08 are more promising to be developed as a superior photosensitizer in DSSCs.

Comparative study of natural and synthetic dyes in DSSCs: An experimental and computational approach

This study explores the natural and synthetic dyes as sensitizers for dye-sensitized solar cells (DSSCs). Anthocyanin dye extract (PG) from pomegranate (Punica granatum) fruit, betanin pigment (BR) from beetroot (Beta vulgaris), and the commercially available organic dye, Rose Bengal (RB), were investigated as sensitizers for DSSCs and their photovoltaic performances were recorded. Density functional theory (DFT) and time-dependent DFT (TD-DFT) studies have also been performed in order to get insight into the photophysical and photoelectrochemical properties. The overall efficiencies (η) of 0.34%, 0.30%, and 0.25% were obtained for the PG, BR, and RB dyes under 1 sun illumination, respectively. The results infer that PG dye would act as a promising photo-sensitizer for DSSCs as compared to BR and RB sensitizers, which may be due to better interaction between anthocyanin molecule of pomegranate extract and TiO2.

Development of natural dye photosensitizers for dye-sensitized solar cells: a review.

Dye-sensitized solar cell (DSSC) is a photovoltaic device that can be produced from natural source pigments or natural dyes. The selection of natural dyes for DSSC application is currently under research. The utilization of natural dye materials that are easy to obtain, cost-effective, and non-toxic can reduce waste during DSSC fabrication. Natural dyes can be extracted from plants through extraction and chromatography methods. The suitability and viability of utilizing natural dyes as photosensitizers in DSSCs can be predicted using appropriate software simulation by varying related parameters to produce high power conversion efficiency. In this context, the purpose of the review is to highlight the evolution of performance improvement in the development of DSSCs with consideration of natural dye extraction and software simulation. This review also focuses on the results of extracting natural dyes from herbal ingredients, which are still very limited in information, and several parts of herbal plants that can be used as natural dye sources in the future of solid-state DSSCs have been identified. Based on the results of this review, the highest efficiency was obtained for the DSSC that used chlorophyll pigments as natural dyes using Peltophorum pterocarpum leaves with 6.07%, followed by anthocyanin pigments as natural dyes using raspberries (black) fruits with 1.5%, flavonoid pigments as natural dyes using Curcuma longa herbs with 0.64%, and flavonoid pigments as natural dyes using Indigofera tinctoria flowers with 0.46%.

First-Principles Investigations of Novel Guanidine-Based Dyes.

In the pursuit of finding efficient D-π-A organic dyes as photosensitizers for dye-sensitized solar cells (DSSCs), first-principles calculations of guanidine-based dyes [A1-A18] were executed using density functional theory (DFT). The various electronic and optical properties of guanidine-based organic dyes with different D-π-A structural modifications were investigated. The structural modification of guanidine-based dyes largely affects the properties of molecules, such as excitation energies, the oscillator strength dipole moment, the transition dipole moment, and light-harvesting efficiencies. The energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is responsible for the reduction and injection of electrons. Modification of the guanidine subunit by different structural modifications gave a range of HOMO-LUMO energy gaps. Chemical and optical characteristics of the dyes indicated prominent charge transfer and light-harvesting efficiencies. The wide electronic absorption spectra of these guanidine-based dyes computed by TD-DFT-B3LYP with 6-31G, 6-311G, and cc-PVDZ basis sets have been observed in the visible region of spectra due to the presence of chromophore groups of dye molecules. Better anchorage of dyes to the surface of TiO2 semiconductors helps in charge-transfer phenomena, and the results suggested that -COOH, -CN, and -NO2 proved to be proficient anchoring groups, making dyes very encouraging candidates for DSSCs. Molecular electrostatic potential explained the electrostatic potential of organic dyes, and IR spectrum and conformational analyses ensured the suitability of organic dyes for the fabrication of DSSCs.

The Performance Evaluation of Meso-Tetraphenyl Porphyrin and Azo Dyes as Photosensitizers in Dye-sensitized Solar Cells.

The photovoltaic properties of five different mono-azo function and meso-tetraphenyl porphyrin dyes have been investigated by computational DFT/TDDFT calculations and measurement of the J-V properties of their cells. The photovoltaic efficiency of the cells based on these dyes were determined by both experimental and theoretical methods. The efficiency-to-cost ratios of the azo-dye cells showed that they could be cheaper substitutes to porphyrin-based cells. Eriochrome blue black (EBB) and eriochrome black T (EBT) cells were shown to possess the best photovoltaic properties by the two methods employed (theory and experiment). The presence of two naphthol moieties at both ends of their -N = N- group has been adduced as possible reason for their relatively outstanding performance. The extremely low efficiency-to-cost ratio obtained for cell-POR suggests that the use of porphyrin as sensitizer may not be as economically viable as some azo dyes. MTO, EBB and EBT were found to be the most cost-effective among the investigated dyes. The porphyrin's low performance may have been amplified by the absence of an effective anchor group in its molecular structure.

Utilization of natural dyes extracted from mustard flower (Genus: Brassica, Species: Napus) as photosensitizer for DSSC: Experimental and computational studies

Dye-sensitized solar cells (DSSC) are considered as one of the most promising photovoltaic technologies, while exploring alternatives to traditional silicon-based solar cells. Dye sensitizer is a very important component of DSSC and the use of natural dyes in these cells is a promising development for this technology, as it has non-hazardous impact on the environment. This work reports the new natural dye extracted from Brassica Napus flower petals and used as sensitizer in TiO2 based DSSC. UV–Vis spectra showed the presence of carotenoid and flavonoid pigments along with broad absorption in dye loaded TiO2. FITR revealed functional groups in the Brassica Napus dye extract. Mass spectroscopy was used to find major constituents present in extract. With the natural Brassica Napus sensitizer and TiO2, photovoltaic performance results viz. conversion efficiency (ɳ%) 0.062, short circuit current density (Jsc) 0.45 mA/cm2, open circuit voltage (Voc) 0.260 V and fill factor (FF) 0.52 were observed. Further, HOMO-LUMO levels of constituents present in Brassica Napus have been measured via CV measurements and compared with relative energetic obtained by computational studies. The transport characteristics revealed from EIS studies were used to rationalize the observed photo-voltaic performance of the DSSC.

Carboxy-substituted D-π-A arylated chalcones: Synthesis, photophysical properties and preliminary evaluation as photosensitizers for DSSCs

Chalcones are versatile molecules with potential use in various fields and technologies. The judicious choice of chalcones’ building blocks allows the design of compounds with different properties and applications. In the present work, four highly conjugated carboxy-substituted chalcones with D-π-A architecture were synthesized aiming their evaluation as photosensitizers for dye-sensitized solar cells (DSSCs). In their architecture, electron-rich aldehydes were used as precursors of the donor units, and carboxylate or cyanoacrylate acceptor units were bonded to the acetophenone portion. The compounds presented intense UV–vis absorptions (ε in the order of 104 mol L−1 cm−1) centered between 322 and 429 nm, and blue to yellow fluorescence, with quantum yields ranging from less than 0.01 to 0.35. These chalcones were evaluated as photosensitizers for DSSCs, displaying short-circuit current density (ISC) ranging from 0.18 to 0.36 mA cm−2, open circuit voltage (Voc) from 0.52 to 0.56 V, fill factor (FF) between 54 and 67%, and power conversion efficiency from 0.05 to 0.13%. The two best performances were obtained with photosensitizers 6a and 7b which display the pairs dimethylaminophenyl/carboxylate and vanillin/cyanoacrylate as the donor and acceptor/anchoring units, respectively.

Exploring the potential of natural dyes in DSSCs: Innovations for efficient light harvesting and charge separation through Co-sensitization

Dye-sensitized solar cells (DSSCs) are a cost-effective and environmentally benign third-generation photovoltaic technology that is gaining prominence in the changing renewable energy sector. Our study presents the concept of co-sensitization, which involves the combination of TiO2QD with MWCNT/TiO2, in order to improve the efficiency of solar energy conversion greatly. The efficiency of these solar cells is highly dependent on the efficacy of the dye as a photosensitizer. The results indicate that DSSCs employing the co-sensitized approach with TiO2QD achieved an efficiency (η) of 0.331, an open circuit voltage (Voc) of 0.539 (V), a short circuit current density (Jsc) of 0.095 (mA/cm2), and a fill factor (FF) of 37 %. On the other hand, DSSCs utilizing the MWCNT/TiO2 photoanode demonstrated an efficiency (η) of 0.213 %, an open circuit voltage (Voc) of 0.509 (V), a short circuit current density (Jsc) of 0.076 (mA/cm2), and a fill factor (FF) of 17 %. In the ever-changing world of renewable energy, cutting-edge methods like co-sensitization could boost solar energy conversion technology efficiency and sustainability. Innovative methods like employing plant leaf dye as photosensitizers for DSSCs are eco-friendly and could cut production costs. Using natural dyes supports sustainable practices and makes solar energy production more affordable and accessible.

Improved the DSSCs performance by sensitizing eight natural dyes and varying the annealing process on the TiO2

The use of natural photosensitizers applied to dye-sensitized solar cells (DSSCs) is the key to getting inexpensive and abundant materials for solar cells. However, the low recorded efficiency remains a crucial concern. Here, we investigated and extracted eight natural dyes as photosensitizers for DSSCs intensively. We also studied the impact of annealing on the photoanode’s titanium dioxide (TiO2). First, from the characterization measurements, we found the compound of all the dyes can be utilized in DSSCs, and the performance measurement shows that all natural dyes exhibited great performances as photosensitizers in DSSCs, in which their JSC and VOC values are approximately 0.52–2.88 mA cm−2 and 0.63 to 0.76 V, respectively. The best-recorded conversion efficiency is 4.71%, which was extracted from red gambier fruits. Second, increasing the annealing temperature on the photoanode in our device caused a decrease in the efficiency of the DSSCs. This is caused by the phase of TiO2 changing from anatase to brookite when the temperature increases.

Toward the search for new photosensitizers for DSSCs: theoretical study of both substituted Zn(II) and Si(IV) phthalocyanines.

We report a density functional theory (DFT) study performed for a set of 66 compounds based on zinc(II) and silicon(IV) phthalocyanines (Pcs) with potential applications in dye-sensitized solar cells (DSSCs). The effect of the metal center (Zn, Si), periplanar and axial substituents, and anchor groups like anhydrous, carboxyl, and catechol on the electronic, optical, photovoltaics, and adsorption properties is investigated. Using the TD-DFT methodology and M06 and CAM-B3LYP functionals, we calculated the absorption spectra on optimized structures and in the solution phase but not on structures relaxed in the solvent. We obtained a strong Q band and a weak Soret band in the UV-Vis region, which are attributed to the transitions of type π-π* as described by the Gouterman orbitals. Q bands calculated show absorption up to 667 nm for ZnPcs and up to 769 nm for SiPcs, suggesting an essential role of the metal atom. The systems have a bathochromic effect in the order of secondary amine > primary amine > hydroxyl > amide > ester. We also found that the anhydrous and carboxyl groups favor absorption at longer wavelengths than the catechol group. The ZnPc systems show a slightly larger electron injection ΔGinj (∼1.1 eV) than SiPcs (∼0.9 eV), with similar values for the three anchor groups. The interaction energies (Eint) between ZnPcs/SiPcs and TiO2 in molecular and periodic configuration and corrected by the counterpoise method indicate that SiPcs predict more negative values than ZnPcs. The anchor group effect is relevant; the carboxyl moiety leads to stronger interactions than the anhydrous moiety. The strategies used could help to identify new photosensitizers for DSSCs.

Influence of various solvents in extraction of natural pigments from Annona atemoya and Physalis peruviana as photosensitizers for dye-sensitized solar cells

Herein, we investigate the effect of various solvents on the extraction of natural dyes from two different fruit skins, namely Annona atemoya (Atemoya) and Physalis peruviana (Physalis), as photosensitizers for dye-sensitized solar cells (DSSCs). The functional groups of the extracted dye pigmentation were confirmed using Fourier-transform infrared spectroscopy (FTIR) to verify the presence of anthocyanin radicals. To fabricate the DSSCs, semiconducting TiO2 nanoparticles were deposited on FTO glass as a photoanode (using the spin-coating method), and platinum was also deposited on FTO glass as a photocathode (using the drop-casting method). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were performed to verify the surface roughness and morphologies of the TiO2 photoanode and Pt photocathode. The photoelectric performance results of the fabricated DSSCs were examined and revealed the influence of various solvents on the extraction of Annona atemoya and Physalis peruviana dyes. The extraction of Annona atemoya and Physalis peruviana dyes in methanol solvent showed higher energy conversion efficiency of 2.02 % and 0.31 %, respectively, compared to other solvent extractions. In general, this work demonstrates that constructing solar cells from natural dyes at a reduced cost is a viable and sustainable alternative to traditional silicon cells.

An Overview of Metal Complexes, Metal-Free and Natural Photosensitizers in Dye-Sensitized Solar Cells

An Overview of Metal Complexes, Metal-Free and Natural Photosensitizers in Dye-Sensitized Solar Cells

Performance of dye-sensitized solar cells with mixed three natural pigments and reduced graphene oxide as a counter electrode

This work overviews the effect of combining three natural dyes as a photosensitizer for dye-sensitized solar cells (DSSC). Reduced graphene oxide in this work was used as a Pt-free counter electrode. The dyes consist of curcuminoid (Curcuma longa), chlorophyll (Justicia gendarussa), and anthocyanins (Clitoria ternatea). The effect of absorbance spectrum, Light Harvesting Efficiency (LHE), bandgap energy, and performance of DSSC were also studied. From the result, combination dyes have a broader absorbance spectrum and LHE than a single dyes solution, while the redox potential of the dye produces a similar gap energy (HOMO/LUMO) due to the solvent used to extract the dye, which is around 1.76–1.79 eV. The best result was achieved by a combination of three dyes, Yellow-Green-Blue, which has a short-circuit current density (Jsc) of 6.50 mA/cm2, an open-circuit voltage (Voc) of 0.94 V, a fill factor of 31.2 %, and efficiency of 1.91 %. The performance of the DSSC is not only due to a large amount of photon energy absorbed and adsorbed on the TiO2 surface and the fast electron diffusion rate due to the large LHE and narrow gap energy. Therefore, combining natural dye and using rGO as the counter electrode can improve the performance of DSSC optimally.

Fossil fuel derived GQD as a photosensitizer in dye-sensitized solar cells

Solar energy is an abundantly available renewable source, and several generations of photovoltaic cells have been developed for harnessing it. Dye-sensitized solar cells (DSSC) are viable and potent solar energy harvesters. Sensitizer, a vital part of DSSC, has been researched for years. Alternatively, fossil fuel-Lignite is one of the world's least explored energy sources.Unfortunately, it has been used as a fuel for power generation and tagged as a pollutant. Therefore, in this study, we use lignite-derived graphene quantum dots (GQD) as a DSSC sensitizer and attempt to add value. GQDs with varied bandgaps were obtained and used as sensitizers, and a maximum PCE of 2.87 % was obtained. Additionally, GQD sensitizers were exposed to UV light for 48 h, and the fabricated device exhibited 2.90 % efficiency, showing the photostability of GQDs. Furthermore, the device showed a higher Rrec of 166.57 Ω, substantiating the better performance of DSSC. Thus, sensitizers derived from lignite showed a novel use for feedstock previously used for combustion.

Identification of novel indole-based dyes as active photo-sensitizers: Synthesis, photophysical, electrochemical and computational investigation

Novel D–π–A type indole-based compounds have been designed and synthesized as active photosensitizers for dye-sensitized solar cells (DSSCs). The molecular structures of indole-based compounds were identified and characterized using IR, NMR, and HRMS spectra data. The attributes of the indole-based compounds were evaluated in terms of their optical, electrochemical, light-harvesting efficiency (LHE), HOMO/LUMO level and redox behaviour. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were conducted to disclose the electronic and optical attributes of novel indole-based compounds. All the compounds revealed well-defined absorption with elevated absorptivity and a small band gap (2.89–3.01 eV). The HOMO to LUMO energy transfer percentage obtained from TD-DFT, for the synthesized compounds is in the range of 86%–99%. The projected light-harvesting efficiency (LHE) for the indole-based compounds is between 0.371 and 0.666. The greatest open circuit voltage (Voc) value was found in the methoxyphenyl-substituted indole-based compound, which is advantageous for DSSCs to obtain external maximum power output.