Electrodeposition as a superior route to a thin film molecular semiconductor

Abstract

Electrooxidation to form neutral films of a homoleptic nickel dithiolene [Ni(b-3ted)₂] (1) from an air-stable TBA salt is described [b-3ted = bis(3-thienyl)-1,2-ethylenedithiolene; TBA = tetrabutylammonium]. Films grown by potentiostatic electrodeposition directly onto interdigitated electrode arrays show improved conductivity compared to those formed by solution methods. The grown films are free from residual electrolyte doping, and this technique is shown to yield robust films of reproducible electronic performance. The conductivity of films formed by electrodeposition show gate dependence when grown directly onto field effect transistor substrates. Thin-film X-ray diffraction confirms the electrodeposited films to be of the same polymorph as films and single crystals formed by solution methods. Scanning electron microscopy shows the electrodeposited films to have larger, more connected polycrystalline regions, as well as improved contact with the electrodes.