Work function tuning of tin-doped indium oxide electrodes with solution-processed lithium fluoride

摘要

Solution-processed lithium fluoride (sol-LiF) nanoparticles synthesized in polymeric micelle nanoreactors enable tuning of the surface work function of tin-doped indium oxide (ITO) films. The micelle reactors provide the means for controlling surface coverage by progressively building up the interlayer through alternating deposition and plasma etch removal of the polymer. In order to determine the surface coverage and average interparticle distance, spatial point pattern analysis is applied to scanning electron microscope images of the nanoparticle dispersions. The work function of the sol-LiF modified ITO, obtained from photoelectron emission yield spectroscopy analysis, is shownudto increase with surface coverage of the sol-LiF particles, suggesting a lateral depolarization effect. Analysis of the photoelectron emission energy distribution in the near threshold region reveals the contribution of surface states for surface coverage in excess of 14.1%. Optimization of the interfacialudbarrier is achieved through contributions from both work function modification and surface states.