The Small Business Innovation Research (SBIR) Phase I project proposes to demonstrate a flexible transparent film technology that automatically reflects near infrared (NIR) solar heat above, but allows the same to transmit through below the room temperature. Using the large discontinuous change in refractive indices across a first order phase transition in liquid crystals (LCs), the proposed polymer and LC composite structure shows index matching at lower temperatures but shows significant index mismatching at higher temperatures. The index mismatched polymer and LC structure at higher temperatures is designed to transmit visible light but to reflect a broad band of NIR radiations. The developed film may be laminated or used as retrofits into glass windows for architectural and vehicular applications to reject solar heat on a hot summer day but allows the same to warm the interior on a colder winter day while the glass windows maintain clear at all times. Full use of such films may save consumers billions of dollars annually in air conditioning costs in summer. The flexible polymeric structure with vastly available materials and scalable thin film manufacturing technologies makes the technology economically very attractive and readily affordable, and successful development of the proposed film technology could have enormous environmental and economical impacts
