Large Area Smart Windows for Indoor Light and Heat Modulation Indrajit Mondal, A. K. Singh, S. Kiruthika and G. U. Kulkarni. Centre for Nano and Soft Matter Sciences, Bengaluru- 560013 Smart windows Fabrication of Transparent Flexible Heater Windows that change light transmission properties in response to heat, light or electricity to tune the amount of privacy, light and heat that enter into a space. E.g.- Electro-chromic, Thermo-chromic, Thermo-tropic etc. Opaque Transparent PET-sheet or Glass Coating Crackle precursor Metal deposition & Lift-off Crack template Metal Mesh Due to the growing awareness and demand for less energy consuming building, the glass panels are made smart with many functionalities which are not found in ordinary glass. A Transparent Conducting Electrode ( TCE) or a Transparent Heater (TH) and an active material required for the fabrication of such smart glass. Procedure: Spin coating crackle precursor on glass or PET substrate and self cracking followed by metal deposition and lift-off crackle precursor. °C 30 40 50 60 70 80 90 100 µm 1 cm Wide spectral range transmittance Transparent flexible heater Seamless junctions with high conductivity Conventional TCE- ITO: Expensive, Brittle and chemically less stable. Fabrication of Smart windows Thermo-chromic Display Thermochromic Device Hydrocarbon Hydrogel Metal Mesh PET / Glass carrying metal mesh on top V I II III Translucent VON VOFF Transparent Opaque Filled with Opaque Filled with transparent Hydrogel Coated with opaque thermochromic pigment 3.5 V 1 cm VOFF VON Color and transparency change with applied voltage Fast Switching or response After applying 5V voltage to different segments of display Each segment of the 13-segment flexible display prepared with help of thermo-cromic pigment coated over transparent heater. Further, power supply designed in such a way that it can have control over each segment. According to our choice we display numeric and alphabets on the display. Active materials such as thermo-chromic pigment, hydro-carbon or hydro-gel are coated on the Transparent Heater. A suitable power is supplied to change the color or transparency. Hydrogel based Smart window Hydrocarbon based smart window VON VOFF Upon applying 5 V to this device, the hydrogel temperature increases (>40 °C) and the device becomes opaque because of its transition from a transparent liquid to an opaque gel state. Upon applying 5V, the joule heat generated is transferred to the hydro-carbon layer within the device and it becomes transparent because of its transition. VOFF VON Cyclic stability and Transparency change Advantages: (i) Low fabrication cost, (ii) Good flexibility, (iii) High mechanical and cyclic stability, (iv) Fast response and recovery. Reference: A. K. Singh, S. Kiruthika, Indrajit Mondal and G. U. Kulkarni, J. Mater. Chem. C 2017, DOI: 10.1039/c7tc01489a, Email- guk@cens.res.in, indrajitmondal898@gmail.com