Improvement in Open-Circuit Memory, Current Efficiency and Response Speed of an Amorphous WO₃ Solid-State Electrochromic Device

Abstract

The desirable configuration of an amorphous WO 3 (a-WO 3 ) solid-state electrochromic device (ECD) was examined in order to improve the poor open-circuit memory and low current efficiency observed in an a-WO 3 /Cr 2 O 3 ECD. It was found that a device with an SiO 2 (or Nb 2 O 5 ) layer introduced between the a-WO 3 layer and the Cr 2 O 3 layer exhibited long open-circuit memory and good current efficiency. The charge dissipation in the a-WO 3 /SiO 2 (or Nb 2 O 5 )/Cr 2 O 3 ECD was as low as that in an a-WO 3 /liquid electrolyte ECD. In addition, reactive evaporation of Cr 2 O 3 in an atmosphere of H 2 O activated by thermal electrons was attempted in an effort to better the response speed of the device.