**Summary:**
Scientists at the Centre for Nano and Soft Matter Sciences (CeNS), an autonomous institute under the Department of Science and Technology (DST), Government of India, in Bengaluru, have developed a cost-effective smart window technology using affordable materials. This innovation addresses the high cost barrier associated with conventional electrochromic smart windows, which typically rely on expensive materials like tungsten oxide (WO3) and lithium-based electrolytes.
The researchers replaced WO3 with titanium oxide (TiO2) films and lithium-ion electrolytes with aluminum-ion-based electrolytes. To enhance the coloration performance of TiO2, the team engineered oxygen vacancies in the films. The resulting dual-functional electrochromic device achieved a coloration efficiency of approximately 27 cm2/C, a transmittance modulation of 55% (solar), 47% (luminous), and 41% (near-infrared), using films around 340 nm thick. Furthermore, the films exhibited a real capacitance of 34 µFcm-2, enabling charge storage functionality. The devices demonstrated excellent cycling stability, retaining 96% of their capacity over 2000 switching cycles.
This advancement, utilizing earth-abundant and low-cost TiO2, has the potential to significantly reduce the cost of smart windows, making them more accessible for various applications, including homes, offices, and zero-energy buildings. The research, led by Dr. Ashutosh K. Singh, was published in the journal *Small*. The PIB Delhi released information about this development on July 29, 2025, at 3:44 PM (Release ID: 2149683).
Key Entities Referenced
Ministry of Science Technology: The Indian government ministry responsible for science and technology policy and promotion.
Bengaluru, Karnataka: City in Karnataka, India, where the scientists mentioned in the policy text are located.
Centre for Nano and Soft Matter Sciences CeNS: An autonomous research institute under the Department of Science and Technology (DST) in India, involved in the development of smart windows.
Department of Science and Technology DST: A department under the Government of India, which provides administrative support to CeNS.
Electrochromic smart windows: Smart windows that change color in response to an electrical stimulus, blocking light and heat.
tungsten oxide WO: Conventional material used in electrochromic smart windows, but replaced with TiO in the research.
titanium oxide TiO: A low-cost alternative material used in the development of smart windows.
Dr. Ashutosh K. Singh: The lead researcher at CeNS who led the team that developed the cost-effective smart windows.
Ministry of Science & Technology
Bengaluru scientists develop cost-effective smart
windows
Posted On: 29 JUL 2025 3:44PM by PIB Delhi
Smart windows which can change colour at the flick of a switch, block heat on sunny days, save energy, and
even store electricity may now be made from affordable materials. This advancement offers could make the
smart window technology more accessible.
Electrochromic smart windows change color in response to a small electrical stimulus, enabling
them to block both visible and near-infrared (NIR) light. In doing so, they help reduce energy
consumption in buildings by minimizing heat gain and regulating indoor temperatures. These dual-
functional devices can also store electrical energy, offering a two-in-one solution for sustainable
infrastructure.
Despite their potential in achieving “zero-energy buildings,” electrochromic smart windows have
remained commercially limited due to the high cost of conventional materials such as tungsten
oxide (WO ) and lithium-based electrolytes.
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A team of researchers from Centre for Nano and Soft Matter Sciences (CeNS), an autonomous
institute under the Department of Science and Technology (DST), Government of India,
demonstrated a cost-effective alternative by replacing WO with TiO films and lithium-ion
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electrolytes with aluminum-ion-based electrolytes.
Fig: Photographs show the TiO -based dual-functional electrochromic device in transparent and colored
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states.
Although TiO exhibits electrochromic properties, it has been underexplored due to its relatively low
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coloration efficiency, a measure of optical density changes per unit charge. In this work, however, the authors
engineered oxygen vacancies in the TiO films to enhance coloration performance. As a result, the smart
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window devices achieved coloration efficiency of around 27 cm /C which is among the highest reported for
TiO and a transmittance modulation of 55% (solar), 47% (luminous) and 41% (NIR), all with just around
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340 nm thick films.2
In addition to optical switching, these films demonstrated real capacitance of 34 mF/cm , enabling charge
storage functionality. The devices also showed excellent cycling stability, retaining 96% of their capacity over
2000 switching cycles, which is crucial for the long-term durability of these dual-functional smart windows.
The dual-functional electrochromic smart window based on earth-abundant and low-cost titanium oxide
(TiO ) could cut costs dramatically, making smart windows more accessible for homes, offices and even
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futuristic zero-energy buildings.
This work, led by Dr. Ashutosh K. Singh and his team at CeNS, was recently published in the prestigious
journal ‘Small’.
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NKR/PSM
(Release ID: 2149683)