Polythiophenes Containing Oligo(oxyethylene) Side Chains as a Thin Film on a ZnSe Single Crystal Surface

Abstract

Summary: Two polythiophenes, containing either one (PTT) or two (PBTT) 2,5,8‐trioxanonyl side chains per repeating unit, were synthesized with the objective of developing hybrid inorganic/organic semiconductor systems. From absorption and fluorescence spectroscopy and cyclic voltammetry it appears that introduction of a second 2,5,8‐trioxanonyl side chain on a repeating unit leads to a very short conjugation length. Atomic Force Microscopy (AFM) performed on composites of the two polythiophenes and a ZnSe single crystal reveals excellent wetting of the crystal by the polymers, leading to the formation of thin films. For the PTT/ZnSe composite, good contact between the constituents is substantiated by a red‐shift of the PTT absorption relative to that of PTT on quartz. Fluorescence measurements indicate the occurrence of energy transfer from ZnSe to PTT, which might imply that there is electronic contact between ZnSe and PTT. Because of its highly distorted backbone, neither a significant red‐shift compared with a film on quartz nor excitation energy transfer was found for the thin film of PBTT deposited on ZnSe. Nevertheless, it is shown that the presence of polar 2,5,8‐trioxanonyl side chains guarantees strong binding of polythiophenes to the ZnSe surface.

Selective recognition of biologically important anions using a diblock polyfluorene–polythiophene conjugated polyelectrolyte

“…S7). In forward bias P3TMAHT shows a reversible oxidation band at 1.03 V with a corresponding reduction peak at 0.92 V. These values are slightly higher than the first oxidation peak of the polymer backbone reported for similar polythiophenes containing oligo(oxyethylene) side chains in tetrahydrofuran (0.7 V), 36 but is slightly lower than that of poly(3-hexylthiophene) films in acetonitrile (1.3 V). 37 The CV of P3TMAHT also shows an irreversible reduction peak at -0.01 V, which is most likely to be associated with the charged species on the side chain, as it does not appear in the CV of the neutral homopolymer precursor with bromohexyl side chains, P3BrHT (ESI, Fig S7c).…”

Side Chain Mediated Electronic Contact between a Tetrahydro‐4H‐thiopyran‐4‐ylidene‐Appended Polythiophene and CdTe Quantum Dots

“…Anodic scans revealed a single irreversible oxidation wave centered at 1.0 V versus SCE, whereas cathodic scans exhibited a single irreversible reduction wave centered at À1.7 V versus SCE. The oxidation potential is more positive than that found for poly [3-(2,5,8-trioxanonyl)thiophene] (PTT) in THF (0.8 V versus SCE [43,44] ). The relatively high oxidation potential of poly (4), which may be the consequence of a higher degree of distortion of the polythiophene backbone by the bulky ring-containing substituents, seems to be in disagreement with the observation that the absorption maximum of poly(4) (465 nm for a saturated solution in THF) is situated at a longer wavelength than that of PTT (440 nm in THF [43] ).…”

“…The oxidation potential is more positive than that found for poly [3-(2,5,8-trioxanonyl)thiophene] (PTT) in THF (0.8 V versus SCE [43,44] ). The relatively high oxidation potential of poly (4), which may be the consequence of a higher degree of distortion of the polythiophene backbone by the bulky ring-containing substituents, seems to be in disagreement with the observation that the absorption maximum of poly(4) (465 nm for a saturated solution in THF) is situated at a longer wavelength than that of PTT (440 nm in THF [43] ). This apparent contradiction can be explained only by assuming that the effect of the tetrahydro-4H-thiopyran-4-ylidene substituent on the electronic spectrum of poly (4) is based predominantly on a stabilization of the conduction band.…”

“…[41,43] The fluorescence emission spectrum of poly(4) in chloroform solution ( Figure 1B) has a maximum at 582 nm and a shoulder near 630 nm, representing a vibronic transition. The emission spectrum of the film on quartz is red-shifted, with the maximum now at 665 nm ( Figure 1B).…”

“…A similar phenomenon has been found for PTT deposited on a ZnSe single-crystal surface. [43] The emission spectrum of the mixture, along with the spectra of the individual components, is shown in Figure 2B. The spectra were recorded upon excitation at 406 nm, which implies that in the mixed sample both components were excited.…”