Electrochemical deposition of small molecules for electronic materials

Abstract

The method of the deposition of films of small molecules for use in electronic applications is just as important as the molecule design itself as the film’s morphology and continuity influence the performance of the devices that they are incorporated in. The purpose of the work in this thesis was to develop a method of electrochemically depositing films of small molecules for potential use in electronic applications. A method of electrochemically depositing films of chemically reduced low solubility dye molecules was successfully pioneered. The process was developed using N,N dibutyl-3,4,9,10-perylene-bis(dicarboxime), a simplified version of 3,4,9,10-perylene-tetracarboxylic bisbenzimidalzole. Both of these dyes have been used in electronic applications, but low solubility makes them difficult to deposit by traditional solution techniques. A series of films was electrochemically deposited onto FTO coated glass and field effect transistors using coulometry. These films were characterised by absorption spectroscopy, photoluminescence, scanning electron microscopy, X-ray diffraction and photo-electrochemistry. The same deposition method was applied to copper phthalocyanine. These films were characterised by absorption spectroscopy, photoluminescence, scanning electron microscopy and X-ray diffraction. The developed method was used to deposit films of bilayers of dyes and to investigate the dye penetration during the deposition of copper phthalocyanine onto porous titanium dioxide. Films of neutral copper and nickel dithiolenes were electrodeposited from air-stable TMA salts to investigate the absorbance of the near infrared species formed, as well as to investigate the conductivity of both complexes and the magnetoresponse of the neutral copper dithiolene which is air unstable when formed chemically.