Editorial

3 pages, 178 KiB

Open AccessEditorial

Recent Advances in Dye-Sensitized Solar Cells

by Claudia Dragonetti and Alessia Colombo

Molecules 2021, 26(9), 2461; https://doi.org/10.3390/molecules26092461 - 23 Apr 2021

Cited by 13 | Viewed by 2123

Dye-sensitized solar cells (DSSCs) are an effective alternative for delivering clean energy from the sun compared to the most widely deployed technologies based upon semiconductor photovoltaics [...] Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

Research

Jump to: Editorial, Review

19 pages, 5721 KiB

Open AccessArticle

Density Functional Theory Study of Optical and Electronic Properties of (TiO₂)_n=5,8,68 Clusters for Application in Solar Cells

by Ife Fortunate Elegbeleye, Nnditshedzeni Eric Maluta and Rapela Regina Maphanga

Molecules 2021, 26(4), 955; https://doi.org/10.3390/molecules26040955 - 11 Feb 2021

Cited by 8 | Viewed by 2863

Abstract

A range of solution-processed organic and hybrid organic−inorganic solar cells, such as dye-sensitized and bulk heterojunction organic solar cells have been intensely developed recently. TiO₂ is widely employed as electron transporting material in nanostructured TiO₂ perovskite-sensitized solar cells and semiconductor in [...] Read more.

A range of solution-processed organic and hybrid organic−inorganic solar cells, such as dye-sensitized and bulk heterojunction organic solar cells have been intensely developed recently. TiO₂ is widely employed as electron transporting material in nanostructured TiO₂ perovskite-sensitized solar cells and semiconductor in dye-sensitized solar cells. Understanding the optical and electronic mechanisms that govern charge separation, transport and recombination in these devices will enhance their current conversion efficiencies under illumination to sunlight. In this work, density functional theory with Perdew-Burke Ernzerhof (PBE) functional approach was used to explore the optical and electronic properties of three modeled TiO₂ brookite clusters, (TiO₂)_n=5,8,68. The simulated optical absorption spectra for (TiO₂)₅ and (TiO₂)₈ clusters show excitation around 200–400 nm, with (TiO₂)₈ cluster showing higher absorbance than the corresponding (TiO₂)₅ cluster. The density of states and the projected density of states of the clusters were computed using Grid-base Projector Augmented Wave (GPAW) and PBE exchange correlation functional in a bid to further understand their electronic structure. The density of states spectra reveal surface valence and conduction bands separated by a band gap of 1.10, 2.31, and 1.37 eV for (TiO₂)₅, (TiO₂)₈, and (TiO₂)₆₈ clusters, respectively. Adsorption of croconate dyes onto the cluster shifted the absorption peaks to higher wavelengths. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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15 pages, 3669 KiB

Open AccessArticle

A Combined Experimental and Computational Study of Chrysanthemin as a Pigment for Dye-Sensitized Solar Cells

by Atoumane Ndiaye, Alle Dioum, Corneliu I. Oprea, Anca Dumbrava, Jeanina Lungu, Adrian Georgescu, Florin Moscalu, Mihai A. Gîrţu, Aboubaker Chedikh Beye and Issakha Youm

Molecules 2021, 26(1), 225; https://doi.org/10.3390/molecules26010225 - 04 Jan 2021

Cited by 6 | Viewed by 3152

Abstract

The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO₂-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional [...] Read more.

The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO₂-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional and DGDZVP basis set. A better energy level alignment was found for partially deprotonated molecules of chrysanthemin, with the excited photoelectron having enough energy in order to be transferred to the conduction band of TiO₂ semiconductor in DSSCs. In addition, we used the raw aqueous extracts of roselle (Hibiscus sabdariffa) calyces as the source of chrysanthemin and the extracts with various pH values were tested in DSSCs. The extracts and photosensitized semiconductor layers were characterized by UV-Vis spectroscopy, and DSSCs based on raw extracts were characterized by current density-voltage measurements. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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15 pages, 2094 KiB

Open AccessArticle

Theoretical Analysis on Heteroleptic Cu(I)-Based Complexes for Dye-Sensitized Solar Cells: Effect of Anchors on Electronic Structure, Spectrum, Excitation, and Intramolecular and Interfacial Electron Transfer

by Zhijie Xu, Xiaoqing Lu, Yuanyuan Li and Shuxian Wei

Molecules 2020, 25(16), 3681; https://doi.org/10.3390/molecules25163681 - 12 Aug 2020

Cited by 16 | Viewed by 2881

Abstract

Two groups of heteroleptic Cu(I)-based dyes were designed and theoretically investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Different anchors were integrated into the dye skeleton to shed light on how the type of anchor influenced the electronic structure, absorption [...] Read more.

Two groups of heteroleptic Cu(I)-based dyes were designed and theoretically investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Different anchors were integrated into the dye skeleton to shed light on how the type of anchor influenced the electronic structure, absorption spectrum, electron excitation, and intramolecular and interfacial electron transfer of dyes. The results indicated that, compared with other dyes, the dyes with cyanoacrylic acid and nitric acid exhibited more appropriate electron distributions in frontier molecular orbitals (FMOs), lower HOMO (the highest occupied molecular orbital) –LUMO (the lowest unoccupied molecular orbital) energy gaps, broader absorption spectral ranges as well as improved spectral characteristics in the near-infrared region and better intramolecular electron transfer (IET) characteristics with more electrons transferred to longer distances, but smaller orbital overlap. Among all the studied Cu(I)-based dyes, B1 and P1 (with cyanoacrylic acid anchoring group) exhibited the best interface electronic structure parameters with a relatively short electron injection time (τ_inj) and large dipole moment (μ_normal), which would have a positive effect on the open-circuit photovoltage (V_oc) and short-circuit current density (J_sc), resulting in high power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Our findings are expected to provide a new insight into the designing and screening of high-performance dyes for DSSCs. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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17 pages, 2118 KiB

Open AccessArticle

Theoretical Study of the Effect of π-Bridge on Optical and Electronic Properties of Carbazole-Based Sensitizers for DSSCs

by Tomás Delgado-Montiel, Jesús Baldenebro-López, Rody Soto-Rojo and Daniel Glossman-Mitnik

Molecules 2020, 25(16), 3670; https://doi.org/10.3390/molecules25163670 - 12 Aug 2020

Cited by 27 | Viewed by 3147

Abstract

Eight novel metal-free organic sensitizers were proposed for dye-sensitized solar cells (DSSCs), theoretically calculated and studied via density functional theory with D-π-A structure. These proposals were formed to study the effect of novel π-bridges, using carbazole as the donor group and cyanoacrylic acid [...] Read more.

Eight novel metal-free organic sensitizers were proposed for dye-sensitized solar cells (DSSCs), theoretically calculated and studied via density functional theory with D-π-A structure. These proposals were formed to study the effect of novel π-bridges, using carbazole as the donor group and cyanoacrylic acid as the anchorage group. Through the M06/6-31G(d) level of theory, ground state geometry optimization, vibrational frequencies, the highest occupied molecular orbital, the lowest unoccupied molecular orbital, and their energy levels were calculated. Further, chemical reactivity parameters were obtained and analyzed, such as chemical hardness (η), electrophilicity index (ω), electroaccepting power (ω+) and electrodonating power (ω-). Free energy of electron injection (ΔGinj) and light-harvesting efficiency (LHE) also were calculated and discussed. On the other hand, absorption wavelengths, oscillator strengths, and electron transitions were calculated through time-dependent density functional theory with the M06-2X/6-31G(d) level of theory. In conclusion, the inclusion of thiophene groups and the Si heteroatom in the π-bridge improved charge transfer, chemical stability, and other optoelectronic properties of carbazole-based dyes. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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9 pages, 1290 KiB

Open AccessArticle

A Fractional Diffusion Model for Dye-Sensitized Solar Cells

by B. Maldon and N. Thamwattana

Molecules 2020, 25(13), 2966; https://doi.org/10.3390/molecules25132966 - 28 Jun 2020

Cited by 11 | Viewed by 2049

Abstract

Dye-sensitized solar cells have continued to receive much attention since their introduction by O’Regan and Grätzel in 1991. Modelling charge transfer during the sensitization process is one of several active research areas for the development of dye-sensitized solar cells in order to control [...] Read more.

Dye-sensitized solar cells have continued to receive much attention since their introduction by O’Regan and Grätzel in 1991. Modelling charge transfer during the sensitization process is one of several active research areas for the development of dye-sensitized solar cells in order to control and improve their performance and efficiency. Mathematical models for transport of electron density inside nanoporous semiconductors based on diffusion equations have been shown to give good agreement with results observed experimentally. However, the process of charge transfer in dye-sensitized solar cells is complicated and many issues are in need of further investigation, such as the effect of the porous structure of the semiconductor and the recombination of electrons at the interfaces between the semiconductor and electrolyte couple. This paper proposes a new model for electron transport inside the conduction band of a dye-sensitized solar cell comprising of

{TiO}_{2}

as its nanoporous semiconductor. This model is based on fractional diffusion equations, taking into consideration the random walk network of

{TiO}_{2}

. Finally, the paper presents numerical solutions of the fractional diffusion model to demonstrate the effect of the fractal geometry of

{TiO}_{2}

on the fundamental performance parameters of dye-sensitized solar cells, such as the short-circuit current density, open-circuit voltage and efficiency. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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17 pages, 2033 KiB

Open AccessArticle

Synthesis of Novel 3,6-Dithienyl Diketopyrrolopyrrole Dyes by Direct C-H Arylation

by Amsalu Efrem Yemene, Vishwesh Venkatraman, David Moe Almenningen, Bård Helge Hoff and Odd Reidar Gautun

Molecules 2020, 25(10), 2349; https://doi.org/10.3390/molecules25102349 - 18 May 2020

Cited by 7 | Viewed by 2763

Abstract

Direct C-H arylation coupling is potentially a more economical and sustainable process than conventional cross-coupling. However, this method has found limited application in the synthesis of organic dyes for dye-sensitized solar cells. Although direct C-H arylation is not an universal solution to any [...] Read more.

Direct C-H arylation coupling is potentially a more economical and sustainable process than conventional cross-coupling. However, this method has found limited application in the synthesis of organic dyes for dye-sensitized solar cells. Although direct C-H arylation is not an universal solution to any cross-coupling reactions, it efficiently complements conventional sp²−sp² bond formation and can provide shorter and more efficient routes to diketopyrrolopyrrole dyes. Here, we have applied palladium catalyzed direct C-H arylation in the synthesis of five new 3,6-dithienyl diketopyrrolopyrrole dyes. All prepared sensitizers display broad absorption from 350 nm up to 800 nm with high molar extinction coefficients. The dye-sensitized solar cells based on these dyes exhibit a power conversion efficiency in the range of 2.9 to 3.4%. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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14 pages, 2448 KiB

Open AccessArticle

Exploring Structure-Property Relationships in a Bio-Inspired Family of Bipodal and Electronically-Coupled Bistriphenylamine Dyes for Dye-Sensitized Solar Cell Applications

by Tamara Al-Faouri, Francis L. Buguis, Saba Azizi Soldouz, Olga V. Sarycheva, Burhan A. Hussein, Reeda Mahmood and Bryan D. Koivisto

Molecules 2020, 25(9), 2260; https://doi.org/10.3390/molecules25092260 - 11 May 2020

Cited by 10 | Viewed by 3528

Abstract

A bio-inspired family of organic dyes with bichromic-bipodal architectures were synthesized and tested in dye-sensitized solar cells (DSSC). These dyes are comprised of a D-π-D-A motif with two triphenylamine (TPA) units acting as donors (D) and two cyanoacetic acid acceptors (A) capable of [...] Read more.

A bio-inspired family of organic dyes with bichromic-bipodal architectures were synthesized and tested in dye-sensitized solar cells (DSSC). These dyes are comprised of a D-π-D-A motif with two triphenylamine (TPA) units acting as donors (D) and two cyanoacetic acid acceptors (A) capable of binding to a titania semiconductor. The role of the thiophene π-spacer bridging the two TPA units was examined and the distal TPA (relative to TiO₂) was modified with various substituents (-H, -OMe, -SMe, -OHex, -3-thienyl) and contrasted against benchmark L1. It was found that the two TPA donor units could be tuned independently, where π-spacers can tune the proximal TPA and R-substituents can tune the distal TPA. The highest performing DSSCs were those with -SMe, 3-thienyl, and -H substituents, and those with one spacer or no spacers. The donating abilities of R-substituents was important, but their interactions with the electrolyte was more significant in producing high performing DSSCs. The introduction of one π-spacer provided favourable electronic communication within the dye, but more than one was not advantageous. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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11 pages, 1631 KiB

Open AccessArticle

Push–Pull Zinc Phthalocyanine Bearing Hexa-Tertiary Substituted Carbazolyl Donor Groups for Dye-Sensitized Solar Cells

by Basma Ghazal, Kobra Azizi, Ewies F. Ewies, Ahmed S. A. Youssef, Valid Mwatati Mwalukuku, Renaud Demadrille, Tomás Torres and Saad Makhseed

Molecules 2020, 25(7), 1692; https://doi.org/10.3390/molecules25071692 - 07 Apr 2020

Cited by 12 | Viewed by 2787

Abstract

An asymmetrical, push–pull phthalocyanine bearing bulky tert-butylcarbazolyl moieties as electron donor and carboxylic acid as anchoring group was synthetized and tested as a photosensitizer in dye-sensitized solar cells (DSSC). The new photosensitizer was characterized by 1H and 13C NMR, UV–Vis and mass [...] Read more.

An asymmetrical, push–pull phthalocyanine bearing bulky tert-butylcarbazolyl moieties as electron donor and carboxylic acid as anchoring group was synthetized and tested as a photosensitizer in dye-sensitized solar cells (DSSC). The new photosensitizer was characterized by 1H and 13C NMR, UV–Vis and mass spectrometry. The bulky tert-butylcarbazolyl moieties avoid the aggregation of the phthalocyanine dye. DFT studies indicate that the HOMO is delocalized throughout the -electron system of the substituted phthalocyanine and the LUMO is located on the core of the molecule with a sizable electron density distribution on carboxyl groups. The new dye has been used as a photosensitizer in transparent and opaque dye-sensitized solar cells, which exhibit poor efficiencies related to a low Jsc. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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24 pages, 7471 KiB

Open AccessFeature PaperArticle

Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells?

by Guglielmo Risi, Mariia Becker, Catherine E. Housecroft and Edwin C. Constable

Molecules 2020, 25(7), 1528; https://doi.org/10.3390/molecules25071528 - 27 Mar 2020

Cited by 16 | Viewed by 3206

Abstract

The syntheses of 4,4′-bis(4-dimethylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (1), 4,4′-bis(4-dimethylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (2), 4,4′-bis(4-diphenylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (3), and 4,4′-bis(4-diphenylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (4) are reported along with the preparations and characterisations of their homoleptic copper(I) complexes [CuL₂][PF₆] (L = 1–4 [...] Read more.

The syntheses of 4,4′-bis(4-dimethylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (1), 4,4′-bis(4-dimethylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (2), 4,4′-bis(4-diphenylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (3), and 4,4′-bis(4-diphenylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (4) are reported along with the preparations and characterisations of their homoleptic copper(I) complexes [CuL₂][PF₆] (L = 1–4). The solution absorption spectra of the complexes exhibit ligand-centred absorptions in addition to absorptions in the visible region assigned to a combination of intra-ligand and metal-to-ligand charge-transfer. Heteroleptic [Cu(5)(L_ancillary)]⁺ dyes in which 5 is the anchoring ligand ((6,6′-dimethyl-[2,2′-bipyridine]-4,4′-diyl)bis(4,1-phenylene))bis(phosphonic acid) and L_ancillary = 1–4 have been assembled on fluorine-doped tin oxide (FTO)-TiO₂ electrodes in dye-sensitized solar cells (DSCs). Performance parameters and external quantum efficiency (EQE) spectra of the DSCs (four fully-masked cells for each dye) reveal that the best performing dyes are [Cu(5)(1)]⁺ and [Cu(5)(3)]⁺. The alkynyl spacers are not beneficial, leading to a decrease in the short-circuit current density (J_SC), confirmed by lower values of EQE_max. Addition of a co-absorbent (n-decylphosphonic acid) to [Cu(5)(1)]⁺ lead to no significant enhancement of performance for DSCs sensitized with [Cu(5)(1)]⁺. Electrochemical impedance spectroscopy (EIS) has been used to investigate the interfaces in DSCs; the analysis shows that more favourable electron injection into TiO₂ is observed for sensitizers without the alkynyl spacer and confirms higher J_SC values for [Cu(5)(1)]⁺. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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11 pages, 3165 KiB

Open AccessArticle

Enhanced Power Conversion Efficiency of Dye-Sensitized Solar Cells by Band Edge Shift of TiO₂ Photoanode

by Hye Kyeong Sung, Yeonju Lee, Wook Hyun Kim, Sang-Ju Lee, Shi-Joon Sung, Dae-Hwan Kim and Yoon Soo Han

Molecules 2020, 25(7), 1502; https://doi.org/10.3390/molecules25071502 - 26 Mar 2020

Cited by 14 | Viewed by 2643

Abstract

By simple soaking titanium dioxide (TiO₂) films in an aqueous Na₂S solution, we could prepare surface-modified photoanodes for application to dye-sensitized solar cells (DSSCs). An improvement in both the open-circuit voltage (V_oc) and the fill factor [...] Read more.

By simple soaking titanium dioxide (TiO₂) films in an aqueous Na₂S solution, we could prepare surface-modified photoanodes for application to dye-sensitized solar cells (DSSCs). An improvement in both the open-circuit voltage (V_oc) and the fill factor (FF) was observed in the DSSC with the 5 min-soaked photoanode, compared with those of the control cell without any modification. The UV–visible absorbance spectra, UPS valence band spectra, and dark current measurements revealed that the Na₂S modification led to the formation of anions on the TiO₂ surface, and thereby shifted the conduction band edge of TiO₂ in the negative (upward) direction, inducing an increase of 29 mV in the V_oc. It was also found that the increased FF value in the surface-treated device was attributed to an elevation in the shunt resistance. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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10 pages, 1769 KiB

Open AccessArticle

Effect of Auxiliary Donors on 3,8-Phenothiazine Dyes for Dye-Sensitized Solar Cells

by Audun Formo Buene, Mats Christensen and Bård Helge Hoff

Molecules 2019, 24(24), 4485; https://doi.org/10.3390/molecules24244485 - 07 Dec 2019

Cited by 9 | Viewed by 2573

Abstract

Phenothiazines are one of the more common dye scaffolds for dye-sensitized solar cells. However, these sensitizers are exclusively based on a 3,7-substitution pattern. Herein, we have synthesized and characterized novel 3,8-substituted phenothiazine dyes in order to evaluate the effect of auxiliary donor groups [...] Read more.

Phenothiazines are one of the more common dye scaffolds for dye-sensitized solar cells. However, these sensitizers are exclusively based on a 3,7-substitution pattern. Herein, we have synthesized and characterized novel 3,8-substituted phenothiazine dyes in order to evaluate the effect of auxiliary donor groups on the performance of this new dye class. The power conversion efficiency increased by 7%–10% upon insertion of an auxiliary donor in position 8 of the phenothiazine, but the structure of the auxiliary donor (phenyl, naphthyl, pyrene) had a low impact when electrodes were stained with chenodeoxycholic acid (CDCA) additive. In the absence of CDCA, the highest power conversion efficiency was seen for the phenyl-based sensitizer attributed to a higher quality dye-monolayer. By comparing the novel dyes to their previously reported 3,7- analogues, only subtle differences were seen in photophysical, electrochemical, and performance measurements. The most notable difference between the two geometries is a lowering of the oxidation potentials of the 3,8-dyes by 40–50 mV compared to the 3,7-analogues. The best auxiliary donor for the 3,8-phenothiazine dyes was found to be pyrenyl, with the best device delivering a power conversion efficiency of 6.23% (99 mW cm⁻², 10 eq. CDCA, J_SC = 10.20 mA cm⁻², V_OC = 791 mV, and FF = 0.765). Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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16 pages, 3472 KiB

Open AccessArticle

Theoretical Study of the Effect of Different π Bridges Including an Azomethine Group in Triphenylamine-Based Dye for Dye-Sensitized Solar Cells

by Tomás Delgado-Montiel, Rody Soto-Rojo, Jesús Baldenebro-López and Daniel Glossman-Mitnik

Molecules 2019, 24(21), 3897; https://doi.org/10.3390/molecules24213897 - 29 Oct 2019

Cited by 17 | Viewed by 4277

Abstract

Ten molecules were theoretically calculated and studied through density functional theory with the M06 density functional and the 6-31G(d) basis set. The molecular systems have potential applications as sensitizers for dye-sensitized solar cells. Three molecules were taken from the literature, and seven are [...] Read more.

Ten molecules were theoretically calculated and studied through density functional theory with the M06 density functional and the 6-31G(d) basis set. The molecular systems have potential applications as sensitizers for dye-sensitized solar cells. Three molecules were taken from the literature, and seven are proposals inspired in the above, including the azomethine group in the π-bridge expecting a better charge transfer. These molecular structures are composed of triphenylamine (donor part); different combinations of azomethine, thiophene, and benzene derivatives (π-bridge); and cyanoacrylic acid (acceptor part). This study focused on the effect that the azomethine group caused on the π-bridge. Ground-state geometry optimization, the highest occupied molecular orbital, the lowest unoccupied molecular orbital, and their energy levels were obtained and analyzed. Absorption wavelengths, oscillator strengths, and electron transitions were obtained via time-dependent density functional theory using the M06-2X density functional and the 6-31G(d) basis set. The free energy of electron injection (ΔG_inj) was calculated and analyzed. As an important part of this study, chemical reactivity parameters are discussed, such as chemical hardness, electrodonating power, electroaccepting power, and electrophilicity index. In conclusion, the inclusion of azomethine in the π-bridge improved the charge transfer and the electronic properties of triphenylamine-based dyes. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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Review

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20 pages, 1684 KiB

Open AccessReview

Copper Complexes as Alternative Redox Mediators in Dye-Sensitized Solar Cells

by Alessia Colombo, Claudia Dragonetti, Dominique Roberto and Francesco Fagnani

Molecules 2021, 26(1), 194; https://doi.org/10.3390/molecules26010194 - 02 Jan 2021

Cited by 32 | Viewed by 3047

Abstract

Thirty years ago, dye-sensitized solar cells (DSSCs) emerged as a method for harnessing the sun’s energy and converting it into electricity. Since then, a lot of work has been dedicated to improving their global photovoltaic efficiency and their eco-sustainability. Recently, various articles showed [...] Read more.

Thirty years ago, dye-sensitized solar cells (DSSCs) emerged as a method for harnessing the sun’s energy and converting it into electricity. Since then, a lot of work has been dedicated to improving their global photovoltaic efficiency and their eco-sustainability. Recently, various articles showed the great potential of copper complexes as a convenient and cheap alternative to the traditional ruthenium dyes. In addition, copper complexes demonstrate that they can act as redox mediators for DSSCs, thus being an answer to the problems related to the I₃⁻/I⁻ redox couple. The aim of this review is to report on the most recent impact made by copper complexes as alternative redox mediators. The coverage, mainly from 2016 up to now, is not exhaustive, but allows us to understand the great role played by copper complexes in the design of eco-sustainable DSSCs. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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31 pages, 4317 KiB

Open AccessReview

Cause, Regulation and Utilization of Dye Aggregation in Dye-Sensitized Solar Cells

by Fang Xu, Thomas T. Testoff, Lichang Wang and Xueqin Zhou

Molecules 2020, 25(19), 4478; https://doi.org/10.3390/molecules25194478 - 29 Sep 2020

Cited by 33 | Viewed by 4665

Abstract

As an important member of third generation solar cell, dye-sensitized solar cells (DSSCs) have the advantages of being low cost, having an easy fabrication process, utilizing rich raw materials and a high-power conversion efficiency (PCE), prompting nearly three decades as a research hotspot. [...] Read more.

As an important member of third generation solar cell, dye-sensitized solar cells (DSSCs) have the advantages of being low cost, having an easy fabrication process, utilizing rich raw materials and a high-power conversion efficiency (PCE), prompting nearly three decades as a research hotspot. Recently, increasing the photoelectric conversion efficiency of DSSCs has proven troublesome. Sensitizers, as the most important part, are no longer limited to molecular engineering, and the regulation of dye aggregation has become a widely held concern, especially in liquid DSSCs. This review first presents the operational mechanism of liquid and solid-state dye-sensitized solar cells, including the influencing factors of various parameters on device efficiency. Secondly, the mechanism of dye aggregation was explained by molecular exciton theory, and the influence of various factors on dye aggregation was summarized. We focused on a review of several methods for regulating dye aggregation in liquid and solid-state dye-sensitized solar cells, and the advantages and disadvantages of these methods were analyzed. In addition, the important application of quantum computational chemistry in the study of dye aggregation was introduced. Finally, an outlook was proposed that utilizing the advantages of dye aggregation by combining molecular engineering with dye aggregation regulation is a research direction to improve the performance of liquid DSSCs in the future. For solid-state dye-sensitized solar cells (ssDSSCs), the effects of solid electrolytes also need to be taken into account. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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