Bengaluru Scientists Develop Smart Windows to Cut AC Load Using Nanomaterials

While visible light brightens homes and fuels plant life, infrared radiation carries heat energy that can quickly turn enclosed spaces uncomfortably warm.

In a significant leap toward energy-efficient buildings and devices, researchers at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, have devised a new class of smart windows capable of regulating infrared (IR) radiation—an invisible component of sunlight responsible for excessive indoor heating. By fine-tuning the properties of Polymer Network Liquid Crystals (PNLCs) with the addition of nanomaterial flakes of hexagonal boron nitride (h-BN), the team has demonstrated a scalable solution that could substantially reduce reliance on air conditioners.

Why Infrared Control Matters

While visible light brightens homes and fuels plant life, infrared radiation carries heat energy that can quickly turn enclosed spaces uncomfortably warm. The result is higher energy consumption for cooling, particularly through air conditioning, which in turn contributes to rising electricity bills and carbon emissions.

Thus, controlling IR transmission without blocking visible light has become a central challenge in the design of energy-efficient materials and smart window technologies.

The Research Breakthrough

The CeNS team, comprising researchers Gayathri Pisharody and Priyabrata Sahoo, under the guidance of Dr. D.S. Shankar Rao, Dr. Ramakrishna Matte, and Dr. S. Krishna Prasad, explored how tiny h-BN nanoflakes could drastically alter the optical properties of PNLC-based devices.

Their findings, recently published in the Journal of Molecular Liquids, highlight two distinct outcomes:

• Without h-BN: PNLCs form a coarse, bead-like polymer network that scatters very little IR radiation, offering negligible electrical control over heat management.

• With h-BN flakes: The composite forms a smooth, continuous polymer network embedded with nanoscale scattering sites, enabling high-magnitude IR scattering and substantial control over incoming heat.

How It Works

The system’s effectiveness lies in the size compatibility of the h-BN nanoflakes with the polymer fibers. When the flakes are carefully incorporated, they integrate seamlessly, creating a dense network of local scattering centers that reflect and diffuse IR radiation.

Moreover, the state of the liquid crystal during polymerization—ordered versus disordered—affects how the nanoflakes distribute within the matrix, further tuning the material’s optical response.

Electron microscopy confirmed that the optimized nanoflake incorporation produces fine, uniform structures capable of rapid switching between transparent and scattering states when driven by an applied electric field.

Applications and Benefits

The optimized smart windows offer high IR contrast and can switch at fast operating speeds, making them ideal for real-world deployment. In transparent mode, they allow natural sunlight and heat to pass through, while in scattering mode, they block excess IR radiation, reducing indoor heat load.

Potential applications include:

• Energy-saving smart windows for homes, offices, and vehicles.

• Adaptive enclosures in electronic devices to manage thermal load.

• Architectural solutions for sustainable urban infrastructure.

By scaling up production, these smart windows could play a pivotal role in lowering cooling demands, thus cutting down both energy consumption and greenhouse gas emissions.

A Step Toward Sustainable Futures

Union Government-backed initiatives like this underline India’s growing leadership in green materials science. Projects at institutes like CeNS not only push scientific frontiers but also align with global climate goals by offering practical solutions for sustainable living.

As cities grow hotter due to urbanization and climate change, innovations like PNLC-hBN smart windows may soon become essential in designing energy-smart, eco-friendly buildings across India and the world.