Optical Absorption of Poly(thienylene vinylene)-Conjugated Polymers: Experiment and First Principle Theory

Abstract

Optical absorption spectra of poly(thiophene vinylene) (PTV) conjugated polymers have been studied at room temperature in the spectral range of 450 to 800 nm. A dominant peak located at 577 nm and a prominent shoulder at 619 nm are observed. Another shoulder located at 685 nm is observed at high concentration and after additional treatment (heat, sonification) only. Equilibrium atomic geometries and optical absorption of PTV conjugated polymers have also been studied by first principles density functional theory (DFT). For PTV in solvent, the theoretical calculations predict two equilibrium geometries with different interchain distances. By comparative analysis of the experimental and theoretical data, it is demonstrated that the new measured long-wavelength optical absorption shoulder is consistent with new optical absorption peak predicted for most energetically favorable PTV phase in the solvent. This shoulder is interpreted as a direct indication of increased interchain interaction in the solvent which has caused additional electronic energy structure transformations.

Computations of Ground State and Excitation Energies of Poly(3-methoxy-thiophene) and Poly(thienylene vinylene) from First Principles

“…The QP corrected theoretical spectrum correctly reproduces shoulders on a long-frequency wing of the spectrum. These shoulders are attributed to molecular vibrations (at 619 nm) and to the aggregation (at 685 nm) caused by interchain interaction [19]. The shape of the calculated spectrum, however, shows remarkable differences from experimental data (see Fig.…”

“…Our previous work with substituted poly(phenylene vinylenes) (PPV) has resulted in the observation of supramolecular scale quasicrystalline arrangements of these polymers with distinctive unit cell dimensions [19,21,22]. In those reports, both experimental and computational methods were used to confirm the formation of crystalline domains of the PPV conjugated polymer with interchain dimensions on the order of the van der Waals radii which would be expected to lead to a strong interchain interaction.…”

“…The fully relaxed structure was then used to calculate the electronic and optical properties of the conjugated polymer within PP-DFT as implemented in CASTEP. Three dimensional periodicity in this case allows application of ab initio pseudopotential method which makes optical calculations straight forward [19]. Optical absorption spectra of the PTV conjugated polymers are calculated within the independent particles picture (random phase approximation, RPA) employing ultrasoft pseudopotentials [9].…”

“…Calculated optical absorption spectrum of PTV conjugated polymers is shown in comparison with experimental data [24,19] in Fig. 4.…”

Development of nanostructured luminophor coating for broadening of solar cell absorption spectrum

“…We proposed synthesizing specific nanostructured materials based on organic dyes. In order to achieve mentioned goal following composite organic pyrazoline dyes [12,13]: 53SM (base pyrazoline UV dye with 5% addition of polymethylmethacrylate), 59HM (pyrazoline "orange-red" dye with 5% addition of polymethylmethacrylate), 53SC (pyrazoline UV dye with 5% addition of polystyrene), 59HС (pyrazoline "orange-red" dye with 5% addition of polystyrene).…”