Seminar Details

Seminar Title
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New lanthanide based inorganic phosphors intended for solid state lighting:structure- property-coorelations
Seminar Type
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Synopsis Seminar
Department
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Chemistry
Speaker Type
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Student
Speaker Name
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Mr. Marikumar R (Roll No: 515CY6016)
Date  &  Time
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23 Sep 2020  4:30PM
Venue
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online (MS team code: ahd55hr)
Contact
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2667
Abstract
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Extreme effort and research activities are proceeding to find solutions to reduce power consumption and to mitigate global warming. One technology that can address both of these imperative challenges is to use of energy efficient display and lighting technology. Inorganic luminescent materials (phosphors) are key component or integral part of several display devices (including white light solid state lighting (SSL)). Invention of high efficient blue LED by S. Nakamura is considered as a triumph in the field of materials chemistry. Phosphor materials become integral and imperative part in the white light generation in light emitting diodes (LEDs). In order to enhance the overall efficiency as well as the color gamut of the white LED, the red phosphor plays a vital role. The red emitting components has some criteria to participate in the white LED fabrication, such as narrow band emission in the red region, high thermal stability, and high quantum efficiency. In this context, design, synthesis of new red emitting phosphor based on lanthanides were executed and studied their photophysical properties in details. Since, Ln3+ based red emitters showed line like emission due to their f-f transition, which can certainly participate in the improvement in the overall efficiency of white LEDs. Since the trivalent europium based phosphor showed narrow band red emission, however their absorption strength is very weak in the near UV to blue region (where the LED emission occurs). Hence, design of red phosphor with good absorption in the NUV to blue region is imperative research task. In the present study, scheelite structure based mixed metal oxide containing host lattices have been explored for the Ln3+ ion (Eu3+ and Sm3+) accommodation. Since oxide lattices have broad charge transfer band, quantum efficiency and overall efficiency of the red phosphor. The synthesised red components were used to produce the warm white LEDs, these fabricated LEDs showed higher CRI and low CCT values. Also, the Sm3+ as well as mixed ions (trivalent Sm and Eu) based deep-red LEDs were fabricated to study the plant growth application, the red LED spectrum well matched with the phytochrome Pr. In addition, the new ancillary ligand designed and synthesized for EuIII complexation and photophysical study were executed in details. The selected complexes showed excellent QY and used them for white LED, vapolumniscence sensor, and plant growth applications. The detailed results will be presented and discussed.