Optical and electrical analysis of poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) PEDOT:PSS films and characterizations of stretching memory loops based on ITO/PEDOT:PSS/Ag memristor devices

Abstract

Herein, PEDOT:PSS thin films are successfully fabricated using spin-coating Technique. The particle size distributions were analyzed, and the average particle size was around 6.85 ± 0.023 μm. The electrical resistivity of the fabricated films is characterized at temperatures from 300 to 423k by using a standard four-point probe method. The calculated activation energy decreases from 0.546 ± 0.004 to 0.521 ± 0.006 eV as the film thickness increases from 400 to 532 nm, respectively. The observed decrements in resistance with an increase in temperature suggest that the PEDOT:PSS films may help fabricate negative thermistor NTC applications. The sensitivity factor decreased from 6.9 to 3.5 with the increase in temperature from 300 to 423k, respectively. For manufacturing a thermistor with good performance, a suitable material can have a sensitivity parameter α with values between 1 % and 9 %. The spectrophotometric optical properties of the fabricated films are characterized by using the Reflectance and Transmittance at normal incidence. The investigated optical transitions are direct; the lowest is at the optical gap equal to 0.403 eV, and the other is the bandgap and is equal to 3.773 eV. The analyzed real dielectric constant elucidates a negative permittivity at lower energies less than 1.9 eV. The electrical characteristic hysteresis loop of the fabricated ITO/PEDOT:PSS/Ag device reveals a direct proportional stretching relationship between the range of biasing voltage and the area of the nonlinear hysteresis loops. The obtained experimental data elucidates that the estimated resistance of the fabricated ITO/PEDOT:PSS/Ag device is equivalent to the memristor behaviour of two different Low and High Resistance states.