Electrochromic display device manufacture method

A method for fabricating an electrochromic display device including two parallel substrates defining a cavity therebetween, electrodes formed on the respective substrates, layers of electrochromic material disposed between the substrates, and an electrolyte disposed in the cavity defined by the substrates, said method comprising the steps of:

• controlling the humidity of an environment to hold it below a relative humidity of 60% and, simultaneously, an absolute humidity of 1.17.times.10.sup.-2 kg/kg at those times when the humidity of the ambient environment would otherwise exceed said relative humidity of 60% or absolute humidity of 1.17.times.10.sup.-2 kg/kg;
• and
• depositing the layers of the electrochromic material onto the surface of the electrodes in a vacuum chamber positioned in said controlled environment and fabricating the electrochromic display device in said environment from said substrates, electrodes, electrochromic layers and electrolyte.