posted on 2021-08-11, 08:03authored byDaxin Zhang, Shuo Yang, Wenshi Zhao, Lili Yang, Yang Liu, Maobin Wei, Lei Chen, Jinghai Yang
In
the case of bulk heterojunctions (BHJs) of regioregular poly(3-hexylthiophene)
(P3HT) and the soluble fullerene derivative [6,6]-phenyl-C61-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 ∼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 (ρ). More importantly, the low annealing
temperature-dependent frequency shift (ν) is
carefully investigated with ρ, and ρ ∝ (−ν)2. In addition, the connection between
Raman intensity and ρ 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.