Spectroscopic characterization of P3HT/SWNT composites synthesized using in situ GRIM methods: Improved polymer ordering via nanoscaffolding

Abstract

Poly(3-hexylthiophene)/single-walled carbon nanotube (P3HT/SWNT) materials are synthesized using an in-situ Grignard metathesis approach. The structural properties and photophysics of the materials are studied using a multitude of techniques, including 1 H NMR, FTIR, UV-vis absorption, Raman, photoluminescence (PL), and transient absorption spectroscopies. P3HT/SWNT composites with high P3HT regioregularity (rr > 96%) are observed. Raman spectroscopic data on the solid samples reveals an increase in the dispersion rate parameter with increasing SWNT concentration, thereby indicating close overlap and strong interactions between P3HT and the carbon nanotubes. Changes in the solution-phase PL quantum yields and excited-state lifetimes relative to pure P3HT support these conclusions, and indicate that strong interactions persist even after the composites are dispersed in organic solvents. The high regioregularity and enhanced P3HT-SWNT interactions are promising attributes for improving the morphology and efficiency of functional P3HT/SWNT materials.

P3HT/graphene composites synthesized usingIn situGRIM methods

“…Similar to 1 H NMR spectroscopy, spectral shifts and changes in the intensity of the FTIR bands can reveal information about the nature and extent of ground‐state interactions between graphene and P3HT. Unlike the FTIR spectra in our previous investigation of SWNT/P3HT composites, wherein the FTIR spectra of the composites were similar to pristine P3HT, we do observe some remarkable changes in the infrared absorption spectra of the P3HT/G composites compared with both pure P3HT and ex situ graphene/P3HT samples. The low energy peak in the composites at ∼500 cm −1 appears to be a graphene feature.…”

“…In an earlier study using FeCl 3 ‐mediated in situ oxidative polymerization of P3HT/G, Saini et al did not report these features . Also, our previous in situ GRIM synthesis of P3HT/carbon nanotube composites did not reveal these new peaks . Thus, it does not appear that the graphene alone, or the GRIM method in the presence of some other carbon allotrope, for example, carbon nanotubes, give rise to these two features.…”

“…We recently carried out in situ syntheses using the Grignard metathesis (GRIM) method to prepare P3HT/SWNT nanocomposites of varying SWNT composition . The GRIM procedure is well‐known to produce highly regioregular P3AT polymers, typically having ≥96% head‐to‐tail compositions.…”

Synthesis and Characterization of Poly(3‐Hexylthiophene) for Organic Solar Cells

“…The aforementioned vibrations are reported by Tamanai et al and Shrotriya et al at around 1456 and 1511 cm −1 . Barrett et al stated that the peaks between 2860 and 2960 cm −1 correspond to CH 2 symmetric stretching and CH 3 asymmetric stretching, while a small peak at 3060 cm −1 was described as CH stretching. In the present work, these absorptions were also observed at around 2852 and 2921 cm −1 , corresponding to the symmetrical and asymmetric stretching of CH 2 .…”