Influence of Effective Mass on Carrier Concentration for PEDOT:PSS and S-PEDOT Thin Films Studied by Ellipsometry and Hall Measurement
Ryota Sato, Yoko Wasai, Yuki Izumi, Keiji Ueno, Hajime Shirai
Abstract
We herein investigate the optical anisotropy, carrier concentration, and carrier mobility in the transparent conductive polymer poly(3,4-ethylendioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and self-doped PEDOT (S-PEDOT) using spectroscopic ellipsometry and Hall measurements in the van der Pauw configuration. The influence of the effective mass on the electrical carrier concentrations and mobility is demonstrated in PEDOT:PSS and S-PEDOT thin films with different carrier concentrations. The optical carrier concentration determined by ellipsometry and Hall measurements in both PEDOT:PSS and S-PEDOT shows good agreement in a collinear relationship by considering the variation of effective mass. Conversely, the electron mobility values obtained from spectroscopic ellipsometry and Hall measurements exhibit rather poor agreement. These findings are thought to originate from the grain boundaries at between PEDOT nanocrystals.