Fluorene based organic dyes for dye sensitised solar cells: structure–property relationships (original) (raw)
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The Journal of Organic Chemistry, 2011
b S Supporting Information ' INTRODUCTION Organic dyes capable of absorbing a visible light have received immense attention since the first report in 1991 by Gr€ atzel and co-workers 1 on nanocrystalline anatase TiO 2-based dye-sensitized solar cells (DSSCs) as potential alternatives to traditional silicon-based inorganic photovoltaic devices. These cells are usually constructed using wide band gap semiconductor oxides such as TiO 2 , a molecular sensitizer, and a redox electrolyte. Recent research has been focused on the methods to optimize the light-harvesting ability of the sensitizers and to realize a more robust electrolyte system. 2À6 Also, interest for organic dyes as an alternative to noble metal complexes has increased because of their many advantages, such as diversity of molecular structures, high molar extinction coefficient, simple synthesis, as well as low cost and environmental friendliness. Metal-free organic dyes based on triphenylamine, fluorene, thiophene, indoline, merocyanine, coumarin, etc. have been developed and found to exhibit promising device characteristics. 7 Despite the intensive efforts by materials chemists to achieve an efficient organic dye, the DSSCs based on Ru complexes dx.
ACS applied materials & interfaces, 2015
Two types of fluorene-based organic dyes featuring T-shape/rod-shape molecular configuration with phenothiazine donor and cyanoacrylic acid acceptor have been synthesized and characterized as sensitizers for dye-sensitized solar cells. Phenothiazine is functionalized at either nitrogen (N10) or carbon (C3) to obtain T-shape and rod-like organic dyes, respectively. The effect of structural alternation on the optical, electrochemical, and the photovoltaic properties is investigated. The crystal structure determination of the dye containing phenyl linker revealed cofacial slip-stack columnar packing of the molecules. The trends in the optical properties of the dyes are interpreted using time-dependent density functional theory (TDDFT) computations. The rod-shaped dyes exhibited longer wavelength absorption and low oxidation potentials when compared to the corresponding T-shaped dyes attributable to the favorable electronic overlap between the phenothiazine unit and the rest of the mole...
Organic Electronics, 2013
New metal free dianchoring organic dyes featuring A-p-D-p-D-p-A (acceptor-p bridge-donor-p bridge-donor-p bridge-acceptor) configuration have been designed incorporating fluorene and oligothiophene units and successfully synthesized. Elongating the conjugation pathway between the donor and acceptor units altered the distance between the anchoring sites besides the absorption and redox properties. These dyes exhibited broad and intense absorption when compared to the corresponding monoanchoring donor-p-acceptor congeners. Though the dye containing bithiophene unit exhibited comparatively low V oc due to low electron life time and facile back electron transfer, showed high power conversion efficiency arising from the good light-harvesting capability attributable to the intense absorption peak in the visible region and enhanced interfacial electron transfer rate. This work demonstrates that the smaller distance of separation between the anchoring units increases the insulating capacity of the molecular layer which retards the back electron transfer.
Fluorine–thiophene-substituted organic dyes for dye sensitized solar cells
Journal of Materials Chemistry A, 2013
Novel triphenylamine (TPA)-based organic dyes were synthesized and assessed for their performance in dye-sensitized solar cells (DSSCs). In the dyes considered the TPA group and the cyanoacetic acid have the role of electron-donor and -acceptor, respectively, whereas a thienyl-fluoro-phenyl-substituted was introduced as p-linker to improve the dye performance in DSSCs. Experimental characterizations empasize that the presence of electron withdrawing substituents in the linker close to the electronacceptor moiety leads to a more efficient intramolecular photoinduced charge transfer. In fact, photovoltaic experiments reveal that the DSSCs based on the thienyl-o-fluoro-phenyl substituted dyes yield a better solar-energy-to-electricity conversion efficiency.
New organic dyes based on a dibenzofulvene bridge for highly efficient dye-sensitized solar cells
Journal of Materials Chemistry A, 2014
Three novel organic dyes, coded TK1, TK2 and TK3, incorporating two donor moieties, cyanoacrylic acid as an acceptor/anchoring group, the dibenzofulvene core and an oligothiophene spacer in a 2D-p-A system, were designed, synthesized, and successfully utilized in dye-sensitized solar cells. The dye TK3, containing two thiophene rings as spacers, shows an IPCE action spectrum with a high plateau from 390 nm to 600 nm, increased open-circuit photovoltage by 40 mV and short-circuit photocurrent by 7.03 mA cm À1 , with respect to TK1. Using CDCA as the co-adsorbent material, the J sc of TK3 was increased to 14.98 mA cm À1 and a strong enhancement in the overall conversion efficiency (7.45%) was realized by TK3 compared to TK1 (1.08%), in liquid electrolyte-based DSSCs. † Electronic supplementary information (ESI) available: Synthesis, characterization and computational details of the resulting sensitizers. See
Journal of Computational Chemistry, 2011
The ground state structure and frontier molecular orbital of newly synthesized carbazole-fluorene based D-p-A organic dyes, CFP1A, CFP2A, CFP1CA, and CFP2CA, were theoretically investigated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. These dye molecules have been constructed based on carbazole-fluorene as the electron-donating moiety while introducing benzene units as p-spacer connected to different anchor groups, such as acrylic acid and cyanoacrylic acid, as acceptors. The electronic vertical excitation energies and absorption wavelength were carried out using time-dependent DFT (TD-DFT). Furthermore, the adsorptions of phenylacrylic acid and phenylcyanoacrylic acid on the TiO 2 anatase (101) surface were carried out by means of quantum-chemical periodic calculations employing periodic PBE functional with DNP basis set. The results promise that anchor dyes with strong withdrawing CN group have easier injected electron to the conduction band of semiconductor implying that CFP1CA and CFP2CA show better performance among four dyes. Additionally, the intramolecular charge transfers (ICT) from electron donor group to anchoring group of CFP1CA and CFP2CA have shown better performance. The calculated results provide the efficiency trend of our new dyes as CFP1CA % CFP2CA [ CFP1A % CFP2A which are excellently agree with experimental observation. q 2011 Wiley Periodicals, Inc. J Comput Chem 32: 1568-1576, 2011
Novel Conjugated Organic Dyes for Efficient Dye-Sensitized Solar Cells
Advanced Functional Materials, 2005
A new metal-free sensitizer 2-[3-(4-dimethylamino-phenyl)-allylidene]-malonic acid (2) has been synthesized by the condensation of N,N'-dimethylaminocinnaldehyde and malonic acid. This dye has two carboxyl gmups on the same carbon atom, which act as better electron withdrawing groups in addition to providing effective anchoring to titanium dioxide. The new dye has characterized by UV-Vis, 'H NMR and CHN analysis. Dye-sensitized nanocrystalline-titanium dioxidesemiconductor solar cells (DSSC) have been tested in a stable and durable redox electrolyte. The efficiency of dye is as high as 1.38%. The dye molecule is thermally stable up to 100°C. TPC Code : C09B ; H0 1 L3 1/00
Biointerface Research in Applied Chemistry
In this paper, a theoretical study has been carried out. This study concerns four organic dyes with structure D–π–A on the base of triphenylamine; we choose thiophene and thieno [3, 4-b] pyrazine group as a donor and the group cyanoacrylic acid as an acceptor bridged by four conjugated spacers consisting of phenyl, pyrrole, thiophene, and furan. Our studied dyes' ground state geometric and electronic properties are calculated after optimization in their fundamental states with DFT / B3LYP / 6−311G (d, p). Using this method, EHOMO, ELUMO, bandgap energy, λmax, chemical reactivity indices, dipole moment, the Voc, molecular electrostatic potential (MEP), the LHE, the free injection energy (ΔGinj), the regeneration energy (ΔGreg), and the total reorganization energy (λtot) for all these dyes have been calculated and discussed. The optical properties such as Etr, the maximum wavelength (λmax), and the corresponding oscillator strengths have been carried out by the TD−DFT method at CA...
New organic materials based on D–π–A structure for application in dye-sensitized solar cells
Research on Chemical Intermediates, 2018
We used density functional theory at B3LYP level with 6-31G(d,p) basis set for all atoms to study the electrochemical, photovoltaic, and absorption properties of four new organic p-conjugated donor-p-acceptor structures based on diketo-pyrrolo-pyrrole for use in dye-sensitized solar cells (DSSCs). Meanwhile, the cyanocarboxylic acid function of these compounds was used as electron acceptor to attract electrons from the donor unit via the p-spacer and also to attach the dye to a TiO 2 surface. This study focuses on the effect of the p-spacer on structural, electronic, and photovoltaic properties including the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap, density of states (DOS), ultraviolet-visible (UV-Vis) absorption spectrum, free energy change of electron injection DG inject , light harvesting efficiency, intramolecular charge transfer, and electrochemical properties (chemical potential l, electronegativity v, and global hardness g). Moreover, the structure-properties correlation for all dyes is discussed. Our quantum calculations reveal that the dye based on furan as p-spacer (Dye-Fu) may represent a potential electron donor for use in DSSCs.