First principles investigation on the key factors of broad absorption spectra and electronic properties for oligothiophene and its derivatives for solar cells

Abstract

On the basis of optimized structures of two kinds thiophene oligomers, we investigated the configuration and conformation dependent optical and electronic properties of a or b substituted oligothiophene (PT) and oligo(thienylenevinylene) (PTV) isomers, respectively, at the TD-DFT/6-31þG(d,p)//PBE0/6-31G(d) level. The corresponding properties of polymers were predicted by extrapolation method. The broad absorption regions for polythiophene and/or poly(thienylenevinylene) can be ascribed to the coexistence of various conformational and/or configurational isomers with similar energies and each corresponding excited state possessing different absorption spectrum and overlapping each other. Furthermore, the reorganization energies for electron (k e ) and hole (k h ) of a or b substituted PTV and PT indicate them to be potential ambipolar charge transport materials under the proper operating conditions. Therefore, these results are important because they can provide a rational way for the design of multifunctional materials with broad absorption and ambipolar charge transport properties for solar cells devices.

Thiophene‐Containing Pechmann Dyes and Related Compounds: Synthesis, and Experimental and DFT Characterisation

“…Recent DFT studies at the www.chemeurj.org comparable PBE0/6-31G(d) level of theory have shown that the torsion of the outermost ring of tetrakis(2-thienyl) with respect to the second ring exhibits two minima, at about 20 and about 1508 with barriers of rotation of 3.1 and 2.5 kcal mol À1 , respectively. [23] This correlates well with the experimentally observed non-coplanarity of bithiophene in gas phase.…”

A rational design strategy for donors in organic solar cells: the conjugated planar molecules possessing anisotropic multibranches and intramolecular charge transfer

“…The 6-31G(d) split valence polarized basis set was used throughout because it has been tested extensively and has been shown to yield reliable results for geometries and electronic properties of organic semiconducting materials. [20][21][22][23][24][25] The PBE1PBE 26,27 (also called PBE0) has been recognized to provide reliable predictions and interpretations of the molecular geometries, electronic properties, and optical properties of organic compounds bearing sulfur atoms. [28][29][30][31][32][33] To check the consistency of our calculation, preliminary density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed on BDT and the results were compared with available experimental data.…”

Helical and Nonhelical Structures of Vinylene- and Azomethine-Linked Heterocyclic Oligomers: A Computational Study of Conformation-Dependent Optoelectronic Properties

“…Besides the ease of synthesis and modification of their structures, these azomethine-linked oligomers have numerous advantages in optical and hole/electron transport properties. ,,, Looking at the advantages of these linkages, a number of experimental and computational studies have been carried out to explore the structural details and usability of these heterocyclic conjugated polymers. These polymers have many different possible conformations. , Stabilities of these conformations are discussed in the literature, , but all the results are from studies on small (2 to 4 repeating units) linear oligomers. However, it is known that the intramolecular noncovalent interaction has a major impact on secondary structures like helices for a large π-conjugated oligomer.…”

“…These polymers have many different possible conformations. 28,41 Stabilities of these conformations are discussed in the literature, 28,41 but all the results are from studies on small (2 to 4 repeating units) linear oligomers. However, it is known that the intramolecular noncovalent interaction has a major impact on secondary structures like helices for a large π-conjugated oligomer.…”