This thesis describes a pioneering investigation in which time resolved scanning Kelvin probe microscopy (SKPM) and Raman spectroscopy were combined to identify processes occurring at the interface of inkjet printed poly(3,4-ethylenedioxythiophene ):poly( 4-styrenesulphonate) (PEDOT:PSS) and aluminium and indium tin oxide (ITO) electrodes. In order to undertake these measurements an experimental inkjet printing syst em was designed and constructed capable of robustly inkjetting polymer solu-tions with micron resolution suitable for inkjetting typical polymer device structures . The main findings of the SKPM work showed; (i) that t here was good charge t ransfer between ITO and polymer as indicat ed by the lack of a significant potential drop at the interface, however this was not the case with the aluminium electrodes where large pot ential drops were seen at the interface and (ii) that ionic impurities in the polymer migra ted under an applied electric field to t he electrodes where they were not discharged , res ulting in a collapse of t he potential across the bulk of the polymer. These mechanisms were likely to be those responsible for the I ex: t- n behaviour seen in pot ential step response measurements . This b ehaviour was confirmed by the Raman spectroscopy which showed changes in t he spectra in the range 1200 to 1600cm-1 related to t he structure of the conjugat ed polymer backbone and its doping levels. The observed charge transfer and ionic migration results have significant implicat ions for polymer devices including the efficiency and degradation of PLEDs and FETs and the operating mechanism of polymer memory devices .