Conductive thin films of θ-(BETS)4[Fe(CN)5NO] on silicon electrodes – new perspectives on charge transfer salts

Abstract

An alternate electrodeposition method using large surface silicon electrodes as anodes to prepare thin films of radical cation salts has been developed. We report on its use for the preparation of the radical cation salt containing the BETS molecule [BETS = bis(ethylenedithio)tetraselenafulvalene] and the photochromic nitroprusside [Fe(CN)₅NO]²⁻ anion, i.e. θ-(BETS)₄[Fe(CN)₅NO]. The use of various techniques, such as SEM/EDX, XPS, X-ray, IR and Raman, unambiguously confirmed that the film is made of the θ-(BETS)₄[Fe(CN)₅NO] phase previously obtained as single crystals on platinum electrodes. These results show that it is possible to electrodeposit cation radical salts on silicon wafers. In addition, this new method of electrodeposition proves to be extremely useful for preparing the large amounts of product (several hundreds of milligrams) often required for physical measurements.