patial Control of the Conductivity of Poly(3,4-ethylenedioxythiopehe): Poly(styrenesulfonate) Thin Films

Poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films have undergone treatment from rapid thermal processing and direct ultraviolet irradiation at a wavelength of 254 nm. Through various characterization methods, the underlying physical changes as a result of rapid thermal annealing indicate a shift of morphology that correlates to an increase in material conductivity. Through fitting the electrical transport theory of space charge limited current carrier transportation through polymeric materials to experimental results, this shift of morphology can be linked to an increase in the effective mobility of carriers in PEDOT:PSS. Characterization subsequent to various doses of ultraviolet irradiation exhibits up to a 4 order of magnitude loss in conductivity as a result of exposure. This reduction in conductivity has been determined to arise from a scission process induced by the high energy photons. By applying this previously unexplored direct write patterning technique using ultraviolet exposure, novel device demonstrations of patterned organic light emitting diodes as well as an all PEDOT:PSS capacitive sensing array were implemented. The key feature of such device demonstration being that no physical patterning or structuring of the device was required to obtain proper functionality. Both the rapid thermal annealing and the ultraviolet irradiation are suitable for implementation into a roll-to-roll fabrication process which is critical for taking full advantage of the benefits of polymeric electronic materials such as flexibility and low cost fabrication.Ph.D