Low-voltage electrochromic behaviour of polymer-stabilised liquid crystal with considerable broadband reflection

In this work, a novel method was proposed to achieve electric-induced colouration of polymer-stabilised liquid crystal (PSLC) with considerable broadband reflection. The formation of broadband reflection was due to the introduction of the UV absorber that induced a light intensity gradient within the liquid crystal system and promoted the non-uniform distribution of the pitch. Experiments were performed to optimise the components and polymerisation conditions, allowing the bandwidth to be broadened from 252 nm to 906 nm. The texture of PSLC was characterised using POM, revealing that the planar texture was not disrupted. Thereafter, the addition of ionic liquid as supporting electrolyte enabled the PSLC to be switched from colourless to coloured at DC voltage as low as 1.7 V and the colouration behaviour can be independently modulated by changing the voltage level and the duration. Meaningfully, after the DC electric field was removed, the colour of the PSLC can also disappear gradually. In addition, the as-prepared electrochromic PSLC presented enhanced UV shielding, IR thermal control efficacy and good colouration performance on flexible substrates, which can be applied to low-energy smart glass and thermal management of buildings. This study provided a promising approach for the development of smart optical devices.