Raman Scattering Methods for Monitoring the Electric Properties of the Postannealed Bulk Heterojunction

In the case of bulk heterojunctions (BHJs) of regioregular poly(3-hexylthiophene) (P3HT) and the soluble fullerene derivative [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM), electrical properties have been studied based on the Raman spectroscopy. Significantly, a well enough noteworthy phenomenon is the return-back shift of the Raman signal at the similar to 1450 cm(-1) with increasing annealing temperature, which was first observed using the normal Raman spectroscopy of the BHJ system. Based on the Herzberg-Teller coupling term in the organic-organic system, the return-back shift may be due to the charge transfer (CT), resulting in the significant change of resistivity (rho). More importantly, the low annealing temperature-dependent frequency shift (nu) is carefully investigated with rho, and rho proportional to (-nu)(2). In addition, the connection between Raman intensity and rho is also established. This study is unprecedented to establish a clear connection between frequency shift and electrical properties, indicating that the Raman technique opens an avenue to analyze the electrical properties and characterize the performance of the battery.

Automated summary

In this study, electrical properties of BHJs formed by regioregular poly(3-hexylthiophene) (P3HT) and the soluble fullerene derivative [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) were investigated using Raman spectroscopy. The study observed a return-back shift in the Raman signal, possibly indicating charge transfer and significant changes in resistivity. Additionally, a correlation between frequency shift and resistivity was established, highlighting the potential of Raman technique in analyzing electrical properties and characterizing battery performance.