Controlling the work function of indium tin oxide with organometallic surface complexes

The reactions of tetra(tert-butoxy)tin and tetrakis(diethylamino)tin with indium in oxide (ITO) give surface-bound tin alkoxide and tin amide complexes respectively. Organic acids with appropriate acidities initiate ligand metathesis with these surface complexes. Surface bound (arylacetylide)tin and (phenoxide)tin species were synthesized in ultra-high vacuum and characterized by X-ray photoelectron spectroscopy, mass spectrometry, and reflective absorption infrared spectroscopy. A series of substituted phenols, with a range of dipole moments and acidities, was reacted with surface-bound tin alkoxide to probe the validity of a dipole-moment model. The use of o- and p-substituted phenoxytin surface complexes demonstrated that dipolar properties of the surface bound species, and not local electronegativity effects, control the work function of ITO.