ITO-free large area PDLC smart windows: a cost-effective fabrication using spray coated SnO₂on an invisible Al mesh

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 SnO₂over 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.