19-Oct-2022: New materials developed can help move towards stable LEDs emitting bright light
Plasma treatment of some inorganic nano-materials has shown the way towards bright, stable and affordable light-emitting diodes (LEDs) which can be sources of lighting for the future.
Cost-efficient and bright light-emitting diodes (LEDs) are commonly desired for general light sources, but attaining desired stability and brightness have been challenges for scientists who are looking for new materials that are stable and produce bright emissions and can be commercially viable
Scientists at the Centre for Nano and Soft Matter Sciences (CeNS), an autonomous research institute under the Department of Science and Technology (DST), found that simple plasma treatment of inorganic material of cesium lead halide nanocrystals can lead to an enhanced stabilization many folds showing the promise of bright and stable LEDs.
The team of researchers led by Dr. Pralay K. Santra found a mechanism of plasma treatment induced stability enhancement in inorganic perovskite nano-crystals that could boost their emission. Plasma treatment induces the cross-linking of the organic molecules, oleylamine, present on the surface of the nanocrystals. This creates a stronger network of ligands, providing better encapsulation and higher PL intensity. They have also presented a novel anticounterfeiting application that uses the method of plasma treatment to fabricate covert double-layer security tags. The findings from the present work were recently published in the journal ‘ACS Applied Nano Materials.'
The team has also filed the provisional Indian patent for their discovery and actively looking for partners to commercialize the technique.
18-Aug-2020: Bengaluru scientists fabricate invisible shield for electromagnetic interference
H G Wells’ ‘Invisible Man’ tweaked optical properties of the body to become invisible. Scientists have now achieved a similar feat by designing a metal mesh structure instead of continuous film on desired transparent substrates to make it a transparent shield for electromagnetic interference (EMI). The invisible shield can be used in various military stealth applications and can cover electromagnetic wave emitter or absorber devices without compromising their aesthetics.
Scientists from Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, an autonomous institute of the Department of Science & Technology, Govt. of India have fabricated these transparent and flexible EMI shields made of metal meshes using the crack templating method via spray coating which is pioneered in their laboratory.
The CeNS team has developed a copper metal mesh on polyethylene terephthalate (PET) sheet as its substrate, which exhibited a visible transmittance (T), a parameter of visible transparency of about 85% and sheet resistance (Rs) ~ 0.83 ohm per square. These transparent and flexible EMI shields made of metal mesh coatings on desired transparent substrate they have developed through their research published in the journal ‘Bulletin of Materials Science’ showed remarkably high values for total EMI shielding (SET), with the average value being ~ 41 dB over a wide spectral range of the Ku band (12 to 18 GHz).
Instead of continuous film of metal (Cu) coating on any transparent substrate (glass, PET) where transparency can be compromised. In this method, the CeNS team has deposited metal mesh networks on the substrate, which covers only 7% area of substate, unlike 100% coverage of continuous film. This makes metal mesh transparent compare to continuous metal film. Metal mesh provides better electromagnetic shielding compare to same thickness of continuous metal film where transparency can be compromised.
This metal mesh can be created on any desired substrates such as acrylic, polycarbonate, glass, etc. without compromising the conductivity of the electrodes.
Dr. Ashutosh K Singh, Scientist at CeNS and working on this project, said, “this invention has the potential to satisfy the huge demand for highly effective transparent and flexible EMI shields, which can cover electromagnetic wave emitter/absorber devices without compromising their aesthetics.”
These transparent EMI shields have been exhibited in various prestigious Expos and conferences such as Bangalore INDIA NANO-2018 & 2020, ICONSAT-2018 & 2020, SPIE-2019, etc. for dissemination and marketing purpose. The shields are available for onsite testing and validation purposes.
The team lead by Prof. G U Kulkarni, along with his co-workers from CeNS and industrial partner Hind High Vacuum (HHV) Pvt. Ltd. have set-up a semi-automated production plant funded by DST-Nanomission in CeNS-Arkavathi campus for production of transparent conducting glasses which shows the potential for transparent EMI shields as well.
16-Apr-2020: CeNS develops portable sensor to ease heavy metal detection in water
Centre for Nano and Soft Matter Sciences (CeNS) has developed a compact solid-state sensor to detect the heavy metal ions in water. It is a portable device which can help onsite detection in remote areas.
Heavy metal ions such as lead, mercury and cadmium pose severe potential threats to living beings as they can easily be accumulated in the body and cannot be detoxified by any chemical or biological processes. The health hazards associated with heavy metal ions in water demands the development of efficient and portable sensors for rapid onsite detection of these ions. There is an urge to develop visual sensors, which can effectively detect heavy metal ions rapidly (within seconds) under ambient conditions.
A team of researchers led by Dr. Pralay K. Santra at Centre for Nano and Soft Matter Sciences have developed a compact solid-state sensor to detect the heavy metal ions, e.g., lead ions (Pb2+) down to 0.4 parts per billion (ppb) for efficient onsite detection. The sensor film was prepared by forming a composite between manganese doped zinc sulfide quantum dots and reduced graphene oxide on a glass substrate. These particular quantum dots are water-soluble and have high photoluminescence (~ 30 %) quantum yield, making them suitable for luminescence-based sensing. These quantum dots can be excited with handheld UV light of 254 nm, thus making it a portable device even to remote areas. If a drop of water containing heavy metal ions such as mercury, lead, cadmium, etc. are added to the composite film, the emission of the film quenches within seconds.
This study demonstrates the easy detection of heavy metal ions in water; however, the team is developing strategies to improve the selectivity of the detection.