Charge injection electrolyte composition

In the following, factors external to the actual interfacial supramolecular assembly, which are capable of modifying the photoinduced electron injection process, are considered. This discussion will concentrate on how the rate of charge injection can be manipulated by changing the composition of the electrolyte and by changing the external potential applied to the semiconductor film. 

The GPE was composed of a PEG-based acrylate macromonomer, photoinitiator, plasticiser, glass beads and the electrolyte to compensate for the charge injected into or extracted from the conducting polymer. The ionic conductivity of lithium-PEO has been reported to be at a maximum for a Li/O ratio of 0.04 and hence the composition of the GPE with no plasticiser was prepared with this ratio. The different compositions of the GPEs used in this study are shown in Table 12.1. 

In the non-steady state, changes of stoichiometry in the bulk or at the oxide surface can be detected by comparison of transient total and partial ionic currents [32], Because of the stability of the surface charge at oxide electrodes at a given pH, oxidation of oxide surface cations under applied potential would produce simultaneous injection of protons into the solution or uptake of hydroxide ions by the surface, resulting in ionic transient currents [10]. It has also been observed that, after the applied potential is removed from the oxide electrode, the surface composition equilibrates slowly with the electrolyte, and proton (or hydroxide ion) fluxes across the Helmholtz layer can be detected with the rotating ring disk electrode in the potentiometric-pH mode [47]. This pseudo-capacitive process would also result in a drift of the electrode potential, but its interpretation may be difficult if the relative relaxation of the potential distribution in the oxide space charge and across the Helmholtz double layer is not known [48]. 

---