Efficient electrochromic device employing thermal tolerant hydrogel electrolyte with a wide operating temperature range from -40 to 60°C

Abstract Electrochromism has been demonstrated to be a promising technology for intelligent and energy saving light and/or thermal radiation management. However, the efficient operation of electrochromic devices under real world fickle working temperature caused by the seasonal and regional differences has been rarely addressed, which was of significance for the practical applications. The relatively deteriorative ionic conductivity and/or optical transparency of the electrolyte were identified as the main limiting factor. In this work, we reported an example of stable electrochromic device that can operate efficiently under wide working temperature from -40 oC to 60 oC, by employing thermal tolerant hydrogel electrolytes through composition engineering. The present optimized hydrogel electrolyte showed good anti-freezing ability and heat-resistance, and exhibited high ionic conductivity (>1.1 S m-1) among the wide working temperature (-40 oC–60 oC). Accordingly, the present electrochromic device exhibited fast response time (tb = 1.7s, tc = 2.9s), good coloration efficiency (252.67 cm2 C-1), good switching stability over 1000 cycles under a wide working temperature window (-40 oC ∼ 60 oC). This work reveals the promising potential of thermal tolerant hydrogel electrolytes for practical electrochromics devices under real world extreme working conditions.