Use In Dye-sensitized Solar Cells Research Articles

The effect of applying lead ion to the surface of TiO2 on dye-adsorption rate and photovoltaic properties of solar cells

Lead ion was incorporated into TiO2 layers prepared on an F-doped tin oxide (FTO) substrate. The resulting electrodes (Pb2+-TiO2/FTO) were sensitized with N719 dye and put to use in dye-sensitized solar cells (DSCs). Owing to the electrostatic attraction between the positively charged TiO2 and the carboxylate anions (–COO−) in the N719 dye, more dye was adsorbed into the Pb2+-TiO2/FTO, which required only 2 h for sensitization, than in a reference TiO2/FTO electrode that was sensitized for 8 h. The power conversion efficiency of a DSC with the Pb2+-TiO2/FTO rose to 10.01 % over the efficiency (9.29 %) of the reference device. It was found that the increased dye adsorption in the Pb2+-TiO2/FTO allowed the cells to more efficiently harvest light and collect electrons, resulting in a higher short-circuit current in the DSC. The larger amount of dye also induced a higher open-circuit voltage in the cell by increasing the total number of photoinjected electrons and prolonging their lifetime.

Impact of Various Solvents on Extraction of Anthocyanins from Blueberry for Use in Dye-sensitized Solar Cells

Impact of Various Solvents on Extraction of Anthocyanins from Blueberry for Use in Dye-sensitized Solar Cells

Development of organic co-sensitizers based on piperonal for over 10% efficient ruthenium complex dye-sensitized solar cells

In this study, two new piperonal-based organic dyes, designated D-1–2, were synthesized for use in dye-sensitized solar cells (DSSCs). The dyes studied have a D-π-A configuration and have undergone molecular engineering to fine-tune their spectral properties and energy levels. A comprehensive analysis involving both experimental and theoretical approaches was performed to investigate their optical, electrochemical, photovoltaic, geometrical, and electronic features. These newly developed dyes exhibit notably strong UV–vis absorption, with high molar extinction coefficients, making them an attractive option as co-sensitizers for ruthenium-based dye-sensitized solar cells (DSSCs). Co-sensitization at a concentration of 0.2 mM resulted in a significant increase in the PCEs of DSSCs, ranging from 7.90 % to 10.43 %, compared to the PCE of 7.31 % for DSSCs sensitized solely with N719. The improvement in PCEs can be attributed to the enhanced JCSS and Voc achieved through co-sensitization, highlighting the potential benefits of utilizing co-sensitizers to develop more efficient DSSCs. The highest PCE achieved was 10.43 %, with a Jsc of 19.05 mA.cm−2 and a VOC of 750 mV for the mixed co-sensitizers (D-1 + D-2 + N719). These findings indicate that cocktail co-sensitization is a promising strategy for constructing efficient D-π-A-type sensitizers and for evaluating the performance of DSSCs. Additionally, incident photon-to-current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) studies provide insights into the mechanisms responsible for these improvements. Based on the IPCE study, the increase in Jsc during co-sensitization is due to less photocurrent loss from the electrolyte. EIS experiments showed that making a monolayer of sensitizers that was denser and more organized probably led to less electron recombination between the injected electrons and the electrolyte. This could be because the dyes were absorbed more. The findings of this study suggest that D-1–2 co-sensitizers might be game-changers in the development of more effective DSSCs. In addition, this investigation provides crucial information regarding the underlying systems.

Enhancing optoelectronic properties of phosphonic acid based dyes via donor unit variation: A DFT/TD-DFT investigation

In this work, nine phosphonic acid-based dyes adopting the structure D-π-A′-π-A were designed and examined using the density functional theory (DFT) approach to assess their potential application in dye-sensitized solar cells (DSSCs). By incorporating various donor moieties, including carbazole, triphenylamine, phenothiazine, phenoxazine, and coumarin, the relevant key parameters to short-circuit photocurrent density and open-circuit voltage of the designed dyes were assessed. These parameters include the driving force of electron injection (ΔGinj), the spontaneity of dye regeneration (ΔGreg), the charge transfer distance (DCT), the reorganization energies, and the nonlinear optical (NLO) properties were computed. All calculations were performed via the implicit CPCM method in chloroform as solvent medium. The calculated results reveal that the incorporation of different donor units resulted in a narrower bandgap, higher molar extinction coefficient, red-shift in the absorption spectra, better intramolecular charge transfer, and increase in light-harvesting efficiency for dyes where the donor unit is connected by the phenyl in contrast to the T-shaped structure where the donor unit is connected via the nitrogen atom. These findings offer valuable insights into optimizing the optoelectronic properties of phosphonic acid-based dyes for potential use in DSSCs.

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.

Theoretical and conceptual framework to design D-π-A type organic dyes for application dye-sensitized solar cells

The optimized structures and absorption spectra of five D-A-type organic dyes (M1, M2, M3, M4, and M5) were investigated using Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT). These dyes contain the same electron acceptors and -spacers but distinct 3,6- and 2,7-carbazole electron-donating groups. The results showed coplanar geometries for the dyes, which implied strong conjugation. When intramolecular charge transfer was investigated, it was discovered that 3,6-carbazole had a better capacity to give electrons than 2,7-carbazole. These dyes' projected orbital energy levels indicate that excited dyes might successfully decrease by electrolyte while oxidized dyes could successfully inject electrons into semiconductor conduction bands. The study investigated the suitability of different dyes for use in dye-sensitized solar cells (DSSCs) and found that the M2 dye, which contains a thio group as the terminal electron donor, exhibited the most promising optoelectronic properties. In particular, M2 had a narrow energy gap, superior optical qualities, optimal FMO energy levels, the lowest total value, and greater GInject and GReg values compared to the other dyes tested. These factors contributed to M2's superior photosensitizing performance, suggesting that using M2 in DSSCs may lead to higher optoelectronic characteristics and total energy conversion efficiency compared to using other dyes.

Effect of electron donor groups on the performance of benzothiadiazole dyes with simple structures for dye-sensitized solar cells

Three structurally simple metal-free organic dyes (C1, C2 and C3) with D–A–π–A structure, having benzothiadiazole auxiliary acceptor, benzene π-bridge and cyanoacrylic acid anchoring group, were designed and synthesized for use in dye-sensitized solar cells (DSSCs). Diphenylamine, carbazole and phenothiazine were used as electron donor groups and their effects on the photovoltaic performance were investigated. It was found that C1 dye with diphenylamine donor has the longest maximum absorption wavelength and highest molar extinction coefficient, which is benefical for harvesting more photons and generating a higher photocurrent. Therefore, the DSSC based on C1 dye gives a power conversion efficiency (PCE) of 5.01 %, which is greater than those of C2 dye with carbazole donor (3.51 %) and C3 dye with phenothiazine donor (1.76 %). Finally, the co-sensitization of C1 and C2 exhibits a highest PCE of 5.49 % may be due to broader visible light absorption.

Synthesis of reduced graphene oxide coated with Au@Au2S nanocomposite and study of its photovoltaic properties for use in dye-sensitized solar cells

Synthesis of reduced graphene oxide coated with Au@Au2S nanocomposite and study of its photovoltaic properties for use in dye-sensitized solar cells

Cocktail co-sensitization of two novel metal-free dyes and N-719: A promising strategy for enhanced performance of dye-sensitized solar cells

The present investigation involved the synthesis and characterization of two novel metal-free dyes, MOS-1 and MOS-2, intended for use in dye-sensitized solar cells (DSSCs). MOS-1 and MOS-2 showed strong absorption in the visible region, making them suitable for co-sensitization with N719, a commonly used ruthenium-based dye in dye-sensitized solar cells (DSSCs). We compared the efficiency of DSSCs using MOS-1 and MOS-2 with N719, only MOS-1 or MOS-2, and only N-719. Co-sensitization of MOS-1, MOS-2, and N719 at the same concentration of 0.2 mM resulted in the highest efficiency of 10.45%, which was 1.4 times higher than N-719 alone. MOS-1 and MOS-2 alone also yielded impressive efficiencies of 4.75% and 5.18%, respectively. However, their efficiency was lower than N719 alone (7.27%). The enhanced efficiency of the co-sensitization system can be attributed to broader absorption and efficient electron injection, resulting in increased photocurrent and open-circuit voltage. Further information about the processes accountable for the photovoltaic enhancements was obtained through the utilization of incident photon to current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) evaluations. IPCE results showed that the increase in Jsc was due to a reduction in photocurrent loss caused by the electrolyte (I-/I3-). EIS studies indicated that electron recombination was reduced, likely due to the formation of a more compact and ordered monolayer of sensitizers resulting from increased dye absorption. Co-sensitization with metal-free dyes and N719 is a promising strategy for improving DSSC performance.

Enhanced photovoltaic performance of dye-sensitized solar cells using innovative bithienylnicotinonitrile-based organic dyes

This exciting study introduces five cutting-edge bithienylnicotinonitrile-based organic dyes (coded GA-1-5) that were specifically synthesized for use in dye-sensitized solar cells (DSSCs). These dyes boast a D-π-A framework and were designed to manipulate spectral properties and energy levels. The researchers conducted a comprehensive analysis of their optical, electrochemical, photovoltaic, geometrical, and electronic characteristics using both experimental and theoretical methods. The dyes exhibited intense UV–vis absorption with high molar extinction coefficients, making them ideal co-sensitizers for ruthenium-based DSSCs. When tested, the co-sensitized devices demonstrated significantly improved power conversion efficiencies (PCEs) ranging from 6.22% to 9.12%, thanks to their enhanced short-circuit photocurrents (Jsc), which surpassed those of DSSCs sensitized with N3 alone (PCE = 6.20%). Additionally, GA-1-5 compensated for the photocurrent loss caused by I−/I3 in co-sensitization, further improving the Jsc. We also carried out various spectral and electrochemical characterizations to gain a better understanding of the underlying mechanisms. These findings represent a significant advancement in the field of solar cell technology, paving the way for more efficient and sustainable energy solutions.

Exploring the impact of electron acceptor tuning in D-π-A′-π-A photosensitizers on the photovoltaic performance of acridine-based DSSCs: A DFT/TDDFT perspective

Nine novel organic molecules with D-π-A′-π-A motifs, designated as (Ac-T-Qs-T-CA) and (Ac-T-Bx-T-CA), were proposed as potential photosensitizers for use in dye-sensitized solar cells (DSSCs). These novel organic photosensitizers are comprised of an acridine electron donor (Ac) and a thiophene π-spacer (T), while the electron acceptor unit (A′) is either a substituted quinoxaline (Qs) or a benzo[2,5]diazole-1-heteroatom (Bx), and the anchoring group (A) is 2-cyanoacrylic acid (CA). The influence of electron acceptor (A′) moieties on the electronic, photophysical, thermodynamic and photovoltaic properties of the photosensitizers was analyzed using DFT and TD-DFT calculations. The MM3 force field and CONFLEX conformational search methods were employed to study all possible structural conformations of the photosensitizers. The goal was to identify the lowest energy conformer and gain a better understanding of how the structure conformation and torsional angles of (Ac-T-Qs-T-CA) and (Ac-T-Bx-T-CA) compared to the reference photosensitizer RK1 affect electron injection ability and overall performance of DSSCs. The thermodynamic analysis revealed that the photosensitizers (Ac-T-Q2,3-diOMe-T-CA) and (Ac-T-BtA-T-CA), which contain a 2,3-dimethoxyquinoxaline (Q2,3-diOMe) and a benzo[d][1,2,3]triazole (BtA) acceptor moieties, respectively, exhibit a noteworthy enhancement in their electron-injection free energy (ΔGinj) and a reduction in their recombination-free energy (ΔGrec) values, leading to an improvement in the overall photovoltaic properties of the solar cell when compared to the other photosensitizers. The photovoltaic characteristics of the photosensitizers showed that the photosensitizer (Ac-T-Q2,3-diOMe-T-CA) demonstrated the highest values of open-circuit photovoltage (Voc = 1.41 eV) and light harvesting efficiency (LHE = 0.80 eV) compared to the other (Ac-T-Qs-T-CA) photosensitizers. Similarly, (Ac-T-BtA-T-CA) photosensitizer demonstrated the highest Voc (1.08 eV) and LHE (0.75 eV) among (Ac-T-Bx-T-CA) photosensitizers. The photovoltaic performance of these new photosensitizers outperformed the reference RK1 photosensitizer, which only achieved a Voc of 1.2 eV and LHE of 0.61 eV. Finally, the electronic structures and optical properties of photosensitizers adsorbed on the TiO2 surface were studied to provide more accurate information about their adsorption on the semiconductor surface.

Syntheses, DFT studies and comparatively photovoltaic applications of some pyrene-imine hybrid derivatives

In this study, (E)-N-phenyl-1(pyren-1yl)methanimine (3) and a isomeric mixture of 5ZZ and 5EE (1,4-phenylenebis(1-(pyren-1-yl)methanimine) were synthesized by condensation of pyrene-1-carbaldehyde (1) with aniline (2) or benzene-1,4-diamine (4) The synthesized compounds were characterized using NMR, UV–vis, IR and HRMS spectroscopic techniques.Utilizing the density functional theory (DFT) and a basis set of B3LYP/6-311G(2d,2p), theoretical computations were done. The computed values were applied to simulated spectra of compounds 3 and the isomeric mixtures 5EE, and 5ZZ demonstrating good agreement with observed spectra. In various solvents, the UV–vis spectra of compounds 3, 5EE, and 5ZZ were recorded in areas 200–500 nm, and function density theory (DFT) and time-dependent density functional theory (TD-DFT) algorithms were used to determine if they can serve as metal-free organic dyes in the use of dye-sensitized solar cells (DSSCs). The charge separation distance (Δr) between an electron and the hole it corresponds to was investigated in addition to the degree of electron-hole overlap (Λ) because transition density matrices (TDM) give information about how each electron departs from its corresponding hole during excitations, resulting in charge transfer (CT). To obtain more insight into the characteristics of complexes, the Mulliken population approach, density of states (TDOS), natural population analysis (NPA), molecular electrostatic potential (MEP), condensed Fukui function, and relative nucleophilicity indices derived from orbital charge calculation results (NPA) were used. In addition, the photovoltaic properties of these compounds were studied comparatively. DFT band gap for 3 was 2.493, 5EE was 2.050, and 5ZZ was 2.071 eV. Furthermore, the power conversion efficiency (PCE) values for compound 3 and the isomeric mixture of compound 5 are calculated as 2.31%, and 2.82%, respectively. The results obtained can provide a useful reference for the development of organic compounds containing pyrene units in more efficient organic-based compounds for photovoltaic applications.

Study of electrospun nanofibers loaded with Ru(ii) phenanthroline complexes as a potential material for use in dye-sensitized solar cells (DSSCs)

Study of electrospun nanofibers loaded with Ru(ii) phenanthroline complexes as a potential material for use in dye-sensitized solar cells (DSSCs).

Push-pull photochromic dyes for semi-transparent solar cells with light-adjustable optical properties and high color-rendering index.

We report the design, synthesis and characterization of push-pull photochromic naphthopyran dyes, incorporating different carbazole moieties as the electron-donor group for use in dye-sensitized solar cells. Compared to a reference dye incorporating a diphenylamine-type donor moiety, the introduction of functionalized carbazoles allows for a hypsochromic shift of the absorption of the coloured isomers of the dyes in the visible region and a better tuning of their spectra to the photopic response of the human eye. Under illumination, the molecules exhibit a broad absorption with a maximum comprised between 546 nm and 571 nm in solution and they reveal relatively fast discoloration kinetics. By using these dyes to fabricate photochromic solar cells whose optical and photovoltaic properties vary with the light exposure, we have achieved a PCE of up to 3% in opaque cells. Using these molecules in semi-transparent solar cells with different electrolytes, a PCE of 2.3% was achieved. We also produced a semi-transparent mini-module with an average visible transmittance varying between 66% and 50% and a colour rendering index around 95 in both the uncoloured and coloured states.

Molecular design and synthesis of acetohydrazonoyl cyanide structures as efficient dye-sensitized solar cells with enhancement of the performance of the standard N-719 dye upon co-sensitization

Four novel acetohydrazonoyl cyanide compounds (5–8) with a triphenylamine moiety as an electron donor for use in dye-sensitized solar cells (DSSCs) have been designed and synthesized. The target molecules and their intermediates were well characterized using various spectral techniques. Their absorption spectra and electrochemical and photovoltaic properties are extensively investigated and compared with N-719 dye. The photovoltaic efficiency of these new dyes under AM1.5 ranges from 1.91% to 5.17% without the use of any additive. Compound 8 achieved the highest photovoltaic conversion efficiency (PCE, η = 5.17%) among the existing dyes due to the high values of the photocurrent (JSC = 13.66 mA cm−2) and photovoltage (VOC = 647 mV). Due to the good results shown by compound 8, the compound was used as a co-sensitizer along with the N-719 dye to improve its properties and raise its efficiency. The results showed that using (0.2 mM of compound 8 + 0.2 mM of N-719) improved the performance of the fabricated cell (PCE, η = 8.63%) with the enhancement in both VOC (682 mV) and JSC (20.39 mA cm−2) compared to the cell fabricated with N-719 alone (PCE, η = 6.23%, VOC = 623 mV, JSC = 16.48 mA cm−2). Furthermore, electronic excitations simulated using time-dependent DFT agreed well with experimentally obtained sensitizer results, indicating that the exchange-correlation function and basis set used to predict the spectra of the co-sensitizers are quite appropriate for the calculations. In conclusion, the results showed the potential of simple organic co-sensitizers in the development of efficient DSSCs.

DFT Studies of p-N,N-(Dimethylamino) Benzoic Acid with Para or Meta–Electron Withdrawing or Donating Moieties for Dye-Sensitized Solar Cells (DSSCs)

Solar energy is receiving considerable attention worldwide. Our contribution here focuses on fabricating p-N,N-(dimethylamino) benzoic acid (4-DMABA) donor-π-acceptor derivatives for use in dye-sensitized solar cells (DSSCs). The gas-phase and solvated 4-DMABA and some of its electron donating or withdrawing ortho or meta derivatives were studied theoretically. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were applied to visualize their structural, molecular, photoelectrical, electronic, and photophysical parameters. The parameters for monitoring DSSC efficacies include HOMOs, LUMOs, energy gaps, wavelengths, oscillator strengths, light harvesting efficiencies (LHE), electron injection driving forces (ΔGinject), regeneration driving forces (ΔGregen), open circuit voltages (VOC), and short-circuit current densities (Jsc).

New material for addressing charge transport issue in DSSCs: Composite WS2/MoS2 high porosity counter electrodes

Dye-sensitized solar cells (DSSCs) are among the third generation of solar cells which require further development to find practical applications. One reason that prevents the widespread use of DSSCs is the high cost of their counter electrode (CE). This study proposes a new CE based on WS2/MoS2 material, which demonstrates an excellent performance due to its high electrocatalytic performance and charge transport properties. These qualities are achieved due to the increased active surface area of the composite material. Our champion cell achieved an efficiency of 7.30%, which shows respective improvements of 25% and 18% from the DSSCs fabricated from WS2 and MoS2 CEs. It also displays an efficiency improvement of 3.5% in comparison with the expensive platinum CE. These efficiency enhancements correspond to the increased current densities of the DSSCs as a result of better CE properties.

A roadmap for hydrogel-based quasi-solid electrolyte preparation for use in dye-sensitized solar cell

Although the use of quasi-solid electrolytes in dye-sensitized solar cells (DSSCs) is viewed as a solution to the stability problem of DSSCs, the network structure effect on the DSSCs’ performance has not been studied in detail. Structurally different hydrogels poly (2-methacryloyloxyethyl trimethylammonium chloride-co-acrylic acid) were prepared and used as quasi-solid gel electrolytes in DSSCs to investigate the network structure effect of hydrogels on DSSC performance. The hydrogel's network structure was changed using different amounts of cross-linkers during synthesis. Five quasi-solid electrolytes were prepared from the hydrogels. The increased cross-linking of quasi-solid electrolytes during synthesis raised conductivity from 0.102 to 0.144 S m−1. Despite expectations, it was observed that the energy conversion efficiency of DSSCs does not follow the rising trend in conductivity, as it rises from 6.57% to 6.62% and then decreases to 5.17%, with increased cross-linking. Moreover, cross-linking during hydrogel synthesis defines not only the electrical properties of quasi-solid electrolytes but also the swelling, wetting, and morphological properties of the structure. Therefore, this study aimed to investigate how and which parameters affect the energy conversion efficiency of DSSCs that are prepared with quasi-solid electrolytes.

A Theoretical Evaluation of the Efficiencies of Metal-Free 1,3,4-Oxadiazole Dye-Sensitized Solar Cells: Insights from Electron–Hole Separation Distance Analysis

Herein, some novel metal-free 1,3,4-oxadiazole compounds O1–O7 were evaluated for their photovoltaic properties using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations to determine if they can serve as metal-free organic dyes in the use of dye-sensitized solar cells (DSSCs). To understand the trends in the relative efficiencies of the investigated compounds as dyes in DSSCs, their electron contributions, hole contributions, and electron–hole overlaps for each respective atom and fragment within the molecule were analyzed with a particular focus on the electron densities on the anchoring segments. As transition density matrices (TDM) provide details about the departure of each electron from its corresponding hole during excitations, which results in charge transfer (CT), the charge separation distance (Δr) between the electron and its corresponding hole was studied, in addition to the degree of electron–hole overlap (Λ). The latter, single-point excitation energy of each electron, the percentage electron contribution to the anchoring segments of each compound, the incident-photon-conversion-efficiency (IPCE), charge recombination, light harvesting efficiency (LHE), electron injection (Φinj), and charge collection efficiency (ncollect) were then compared to Δr to determine whether the expected relationships hold. Moreover, parameters such as diffusion constant (Dπ) and electron lifetime (t), amongst others, were also used to describe electron excitation processes. Since IPCE is the key parameter in determining the efficiency, O3 was found to be the best dye due to its highest value.

Effect of carboxylic acid and cyanoacrylic acid as anchoring groups on Coumarin 6 dye for dye-sensitized solar cells: DFT and TD-DFT study

Starting with Coumarin-6 dye, two novel D-π-A organic dyes C6X and C6N have been designed by attaching carboxylic acid and cyanoacrylic acid groups as anchoring groups to Coumarn-6 dye, respectively, to understand their potential use in dye-sensitized solar cells (DSSCs). The electronic structure and photophysical and photovoltaic properties of the novel designed dyes were studied using density functional theory DFT and time-dependent density functional theory TD-DFT with the Becke3-Parameter-Lee–Yang–Parr (B3LYP) functional and the 6-31G (d, p) basis set. Optimized structure and electronic properties (highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital (ELUMO), and energy difference (Eg) between HOMO and LUMO) were calculated showing that C6N has the smallest band gap with the larger absorption region. Density of states (DOS), molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, non-linear optical (NLO) properties, UV–vis spectra, as well as some crucial parameters affecting the photovoltaic performance of DSSCs, such as light-harvesting efficiency (LHE), electron injection driving force (ΔGinject), dye regeneration driving force(ΔGreg), and the excited state life time(τe), were calculated to study the effect of the anchoring group on the DSSC performance. Additionally, the adsorption of C6X and C6N dyes on the TiO2 anatase (101) surface and the mechanism of electron injection were also investigated using a dye–(TiO2)9 cluster model using TD-B3LYP calculation. The calculated adsorption energies of the dyes suggest a strong adsorption of dyes to a TiO2 surface. The results show that C6N may be theoretically a good candidate as sensitizer of DSSC application.