BHUBANESWAR: Scientists from NIT Rourkela, in collaboration with IITs, have developed eco-friendly and lead-free bismuth materials that change colour under UV light, offering a non-toxic alternative for advanced security, sensing, and lighting.
The NIT Rourkela team, along with researchers of IIT Guwahati, IIT Bombay, and NISER Bhubaneswar, have developed the materials which respond to changes in heat and moisture. The materials are safer alternatives to lead-based photoluminescent materials, which are widely studied for their light-emission properties but raise significant environmental and health concerns because of lead toxicity.
The findings of this research have been published in the Journal of Materials Chemistry C, in a paper co-authored by Prof. Saroj L. Samal, Associate Professor, Department of Chemistry, and his research scholar, Subhasish Sahoo, from NIT Rourkela, along with Prof. Parameswar K. Iyer and Chakali Srinivas from IIT Guwahati, Rajanikanta Rana from IIT Bombay, and Prof. Himansu S. Biswal and Laxmipriya Dash from NISER Bhubaneswar.
🔬 NIT Rourkela Develops Lead-Free Materials for Safer Lighting and Anti-Counterfeiting
Researchers from NIT Rourkela, in collaboration with @IITGuwahati , @iitbombay , and @niserbbs , have developed bismuth-based, lead-free light-emitting materials that respond to changes in heat and moisture.
💡 Potential applications include:
🔹 Anti-counterfeiting of certificates, documents, and security labels
🔹 Humidity sensing for food packaging and storage
🔹 Safer, next-generation lighting technologies🔗Read the full story:
The Times of India: https://t.co/gBOlAlMdpA
Odisha Today: https://t.co/pb7YuIJoma
Deccan Chronicle: https://t.co/TRYmhr0xdS…
Utkal Daily: https://t.co/el5uEjnMT3…The findings have been published in the Journal of Materials Chemistry C.
The research was led at NIT Rourkela by Prof. Saroj L. Samal and his research scholar Mr. Subhasish Sahoo, along with collaborators from the partner institutions.
@EduMinOfIndia
#NITRourkela #ResearchInnovation #MaterialsScience #SustainableTechnology #AntiCounterfeiting— NIT Rourkela 🇮🇳 (@nitrourkela) October 29, 2026
The bismuth-based material, when heated, loses water trapped within its structure, allowing it to emit blue light when exposed to UV light. When moisture returns, the material absorbs water again, and the blue light disappears. This process can be reversed by changing the surrounding conditions.
“The Bi-based organic-inorganic hybrid halide compound is synthesised using cheaper and environmentally friendly constituents. The most interesting aspect of this material is its ability to undergo reversible structural transformation in response to heat and moisture, accompanied by change in its light emission properties,” Prof. Saroj L. Samal said.
Anti-counterfeiting applications
This discovery has potential for protecting important documents and products from counterfeiting. For example, special inks containing the developed material can be used on certificates, signatures and security labels. Their light-emitting properties could be checked under UV light after controlled heating, which could help verify whether an item is genuine.
In addition to this, the developed material could also be useful in humidity sensors. Since its light emission changes with moisture, it may help monitor humidity in food packaging, storage facilities and other places where moisture levels need to be controlled.
The NIT Rourkela team has also developed related lead-free LEDs that can produce yellow light when exposed to UV light. The research team combined this yellow-light-emitting material with a commercially available blue-light-emitting material to produce a white LED with a cool, daylight-like appearance.
This resulting white-light system maintained stable light emission during continuous operation, suggesting potential for future lighting and light-conversion applications.
“The synthesised compound shows promising potential for reversible luminescence switching, moisture-sensing, solid-state lighting and anti-counterfeiting applications,” Prof. Samal said.