Thin films of hydroxy-TEMPO-substituted TTF and of its charge-transfer complex with TCNQ

Abstract

Thin films of 4-hydroxy-TEMPO-substituted TTF [TTF-(OH)TEMPO] were grown on ex situ cleaved KBr (001) using the high vacuum evaporation technique. Sub-micronic grains uniformly covering the KBr surface were evidenced by scanning electron microscopy (SEM). The films were also studied by infrared (IR), electron spin resonance spectroscopy (ESR) and X-ray photoelectron spectroscopy (XPS). Amorphous thin films of [TTF-(OH)TEMPO][TCNQ] were obtained on KBr pellets and on micro-rough Si(001) wafers using chemical vapour deposition (CVD). They were characterized by SEM, IR, XPS and ESR. SEM images on micro-rough Si(001) wafers evidenced micro-needles (0.5–2 μm in length, 0.1–0.2 μm in diameter), uniformly covering the substrate surface. CN stretching frequencies were in agreement with a reduced TCNQ moiety, thus indicating a charge transfer between the donor [TTF-(OH)TEMPO] and the acceptor (TCNQ) molecules (degree of charge transfer ∼1).