ITO-free large area PDLC smart windows: a cost-effective fabrication using spray coated SnO2 on an invisible Al mesh

Abstract

Existing liquid crystal (LC) smart window technologies are yet to make inroads into the consumer market largely due to more than 50% of the cost-share of the tin-doped indium oxide (ITO) layer used as the transparent conducting electrode (TCE). In this work, we demonstrate the deployment of a low-cost hybrid TCE as a pathbreaking alternative to ITO in LC smart windows with no compromise in device performance in comparison to standard ITO-based devices. Theoretical modeling puts on a firmer ground the concept of a thin, moderately conducting layer superposed on a micro/nano wire mesh to achieve a uniform electric field, imperative for the efficient operation of LC devices. To illustrate its innovative features, a large-area (10 × 10 cm²) polymer dispersed LC smart window is devised using a hybrid TCE fabricated by spray-coating SnO₂ over an Al mesh formed by the self-crack templating method. The device exhibits a high transparency modulation of ∼94% without any degradation even after 400 days. Further, a new idea of a window-cum-display (60 × 50 cm²) with twelve as-fabricated devices assembled in a 4 × 3 matrix having individual and remote control of each row is demonstrated. Bearing commercialization aspects in mind, the entire fabrication is made industry compatible and scalable.