Nano-doped PDLC combined with photochromic material for bifunctional optical control films

ABSTRACT

Controlling light intensity and colour are the two main functions required to realise smart windows. In this paper, the bifunctional optical control films were prepared by combining a nano-doped polymer-dispersed liquid crystal (PDLC) with the photochromic material. The nano-doped PDLC was prepared by mixing the nematic liquid crystals, UV-curable liquid mixture, and ZrO₂ nanoparticles through a polymerization-induced phase separation (PIPS) process. The electro-optical properties of the PDLCs were significantly improved compared to the initial hybrid system; furthermore, the driving voltage reached a minimum of 20.7 V with 0.8 wt% of ZrO₂ doping. Spin-coated photochromic powder enabled PDLC films to switch between coloured and colourless under UV or solar irradiation. The bifunctional PDLC films with lower threshold voltage, lower saturation voltage, and better contrast, have shown significant application in areas of smart windows.

GRAPHICAL ABSTRACT

The physical picture of spin coating different concentrations of the same photochromic powder:(a) before and after powering up the unspun sample, (b) before and after 10% photochromic powder without light, (c) before and after 10% photochromic powder with light, (d) before and after 20% photochromic powder without light, (e) before and after 20% photochromic powder with a light.

KEYWORDS:

• Polymer-dispersed liquid crystal
• ZrO₂ NPs
• photochromic material
• bifunctional

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [No. 52173263], the Natural Science Foundation of Anhui Province, China [No. 2108085J11], the Regional Innovation Capability Guidance Program of Shaanxi [No. 2022QFY03-02] and the Fundamental Research Funds for the Central Universities, Northwestern Polytechnical University [No. D5000210825].