Raman Changes Induced by Electrochemical Oxidation of Poly(triarylamine)s: Toward a Relationship between Molecular Structure Modifications and Charge Generation

Abstract

Linear, alternating polymers of aromatic amines (p-phenylenediamine, bis(p-aminophenyl)amine, and diaminocarbazole) and either m-phenylene or 3,5-pyridine have been synthesized and characterized by electrochemical and spectroscopic means. The presence of radical cations in their electrochemically oxidized forms is manifested by new bands in the UV-vis-NIR spectra whose appearance can be correlated with reversible redox couples registered in the corresponding cyclic voltammograms at approximately the same potentials as well as with pronounced evolutions of their resonance Raman spectra. Detailed analysis of the Raman data gives information about the locations and the distribution of radical cations and spinless dication in the macromolecule. This approach can provide a new insight into the formation of high-spin states in these polymers.

Heterojunction Doping of Poly(triarylamine) with Cesium-Doped Vanadium Oxide via Interfacial Electron Transfer toward High-Performance Perovskite Solar Cells

“…Raman spectroscopy was conducted to probe the heterojunction doping of PTAA with Cs-doped VO x (Figure ). As presented in Figure a, the Raman spectra of Cs-doped VO x /PTAA display the characteristic Raman peaks of PTAA at 771, 1180, 1209, 1289, and 1605 cm –1 , which are consistent with the Raman spectra of PTAA . Besides the peak at 1289 cm –1 , two new peaks nearby at 1296 and 1305 cm –1 appeared in the enlarged Raman spectra of Cs-doped VO x /PTAA in a region between 1260 and 1340 cm –1 (Figure b).…”

“…Besides the peak at 1289 cm –1 , two new peaks nearby at 1296 and 1305 cm –1 appeared in the enlarged Raman spectra of Cs-doped VO x /PTAA in a region between 1260 and 1340 cm –1 (Figure b). The peak at 1289 cm –1 resulted from the stretching vibration of C–N of PTAA, while the emerging peaks at 1296 and 1305 cm –1 are interpreted as the perturbed C–N stretching vibration mode due to the electron transfer from the nitrogen atom of PTAA to Cs-doped VO x , thus changing the conjugated environment of PTAA after bonding of PTAA to VO x …”

Oriented Two-Dimensional Covalent Organic Framework Films for Near-Infrared Electrochromic Application

“…With the increase of the potential, there are new Raman peaks around 1645 and 1370 cm −1 in the colored state (Figure S18). These two peaks could be attributed to the triphenylamine radical cations and its resonance structure, 67 which further explains the source of NIR electrochromism.…”

Evidence of Porphyrin‐Like Structures in Natural Melanin Pigments Using Electrochemical Fingerprinting

“…Furthermore, the potential of the second plateau in NatMel cathodes is deeper (more negative) than any potential observed in SynMel cathodes prior to full discharge. These data suggest that sodium ions associate with NatMel cathodes at two discrete potentials where, upon the onset of the more negative potential, the frequency of Raman scattering events associated with aromatic amines increases …”

“…Aromatic amines arranged around a porphyrin‐like core produce electronegative sodium ion binding sites with well‐defined insertion potentials. Saturating these binding sites with sodium ions may exfoliate stacked protomolecules and expose Na + ‐loaded electronegative aromatic amines . Conversely, aromatic amines in randomly oriented hyperbranched DHI offer a large distribution of binding sites with various insertion potentials.…”