On the electrochromic properties of antimony-tin oxide thin films deposited by pulsed laser deposition

Antimony-tin oxide (ATO) thin films were deposited using pulsed laser deposition. From a wide survey of deposition conditions (deposition atmosphere and substrate temperature), we deduced that the optimum experimental parameters to obtain electrochromic active films were a deposition temperature of 200 °C at a 10^-2 mbar oxygen pressure followed by an annealing at 550 °C, the latter being critical. Through potentiostatic tests, we showed that depending on the composition, which influences film morphology, the Sn-Sb-O films could present either a faradic or a capacitive-like behavior, associated to a color or a neutral switching over a wide range of potentials, respectively. In addition, a relationship between the film annealing temperature and its structure as well as its electrochromic properties was evidenced by means of complementary electrochemical, X-ray diffraction and electron microscopy techniques. Finally, the electrical and optical properties of the ATO films were discussed in terms of the energy band theory.