Carrier mobility enhancement in poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) having undergone rapid thermal annealing

The conjugated polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is subjected to non-adiabatic rapid thermal processing and exhibits an increase in conductivity through the film. Electrical measurements on an ITO/PEDOT:PSS/Al diode structure display a current-voltage relationship that correlates to space charge limited conduction with the presence of an exponential trap distribution, which is commonly seen in other organic media. With careful application of this current transport theory to the obtained experimental results, the root cause of the conductivity enhancement can be attributed solely to an increase in the charge mobility of carriers in the PEDOT:PSS film. In comparison to an untreated PEDOT:PSS film, processing at 200 °C for 30 s results in a 35% increase in carrier mobility to 0.0128 cm2 V−1 s−1. Values for other material characteristics of PEDOT:PSS can also be extracted from this electrical analysis, and additionally are found to be unchanged with processing. Hole concentration, effective density of states, and total trap density are found to be 7.4 × 1014 cm−3, 1.5 × 1018 cm−3, and 3.7 × 1017 cm−3, respectively.