White Light Emitters For LED Applications

Subject – Science and Tech

Context – IIT-Madras researchers design white light emitters for LED applications

Concept –

Conventional LED materials cannot emit white light and specialised techniques such as coating blue LED with yellow phosphor and combining blue, green and red LEDs, have been used to produce white light.
There has been a worldwide search for materials that can directly emit white light rather than through these indirect techniques that can cause loss of efficiency.
Researchers at the Indian Institute of Technology (IIT) Madras have successfully developed a white light emitter for use in LEDs. The development of energy-efficient Light Emitting Diodes or LEDs replaced the energy-inefficient incandescent lamps in lighting and display applications.
While LEDs have been available in almost all colours, white LEDs are a more recent development.
The innovation has been patented by the researchers and was recently granted the Government of India’s ‘SERB-Technology Translation Award.’
The Science and Engineering Research Board (SERB) provides financial assistance to researchers, academic institutions, research and development laboratories, industrial concerns, and other agencies.
The team proposes to use the grant money of Rs 30 lakh to produce LEDs using their distorted perovskite materials.

The researchers developed expertise in tuning the material at an atomic level to obtain different properties.
Through a recent project that included simulation and experimental work, the team distorted the crystal structure of this material to obtain a natural white light emitter.
The strategic introduction of distortion in halide perovskite generated intense light covering the complete visible spectrum. These materials show at least eight times intense white light emission compared to the conventional Ce:YAG emitters.
This distorted perovskite can be used independently as a white light emitter or as a phosphor in combination with blue LEDs to produce white light.
Unlike other recently developed white LED materials, this distorted perovskite showed phenomenal stability under ambient conditions.
The emission of intense light and stability make them useful in long-lasting, energy-saving lighting applications.
Apart from general lighting, white LEDs can potentially be used in liquid crystal display backlights, display mobile lighting and medical and communication equipment.