Injection-induced de-doping in a conducting polymer during device operation: Asymmetry in the hole injection and extraction rates

Abstract

Injection-induced De-doping in a conducting polymer, poly(3,4- ethylenedioxythiophene) (PEDT) poly(styrenesulfonic acid)(PSSH) during device operation was reported. PEDT:PSSH is strongly acidic on account of the excess PSSH, and often contaminated with ions leftover from the oxidation reaction. The hole extraction PEDT+ → PEDT0 + h+ at the negative contact occurs more readily than hole injection from the opposite contact, which builds up a transient population of PEDT+ of a lower oxidation state across the electrode gap. Electrochemistry occurs in PEDT:PSS to give gas evolution and film spalling. The value across a lateral Au electrode gap was mapped using the Raman spectroscopy to determine whether the doping level of PEDT is permanently altered. The de-doping was confirmed by Fourier Transform Infrared Spectroscopy, which shows loss of the doping-induced infrared modes.