Fractal surfaces of 8-(hydroxyquinoline)zinc and their relation to electroluminescence behaviour

A method has been developed for analysing the fractal surface behaviour of 8-(hydroxyquinoline)zinc (Znq2) using small-angle X-ray scattering (SAXS). The measurements indicated that the surface of Znq2 can be described by fra ctal and power-law decay of the scattering intensity I for values of the sc attering vector q between 0.8 nm(-1) and 5 nm(-1) where I(q) - q(alpha). Th e exponent is smaller than the four values given by Pored's law. The surfac e fractal dimension Ds was found to be 2.96 in agreement with surface fract als. We also report the fractal surface characteristics of 8-(hydroxyquinol ine)aluminum (Alq3) and make a comparison between the fractal surface behav iours of Znq2 and Alq3. We believe that SAXS is the most appropriate techni que for the determination of the fractal dimension and that it can be used to study the relations between the surface and electro-optical properties o f organic materials.