dc.description.abstract | With the rapid technological advancements engulfing the world for better future, human friendly technological approach is all that counts. Researchers have been carrying out intense research in the fields of device physics and fabrications suitable for the fields of medicine, research, defense systems, space technologies, displays, etc. A shift in the trends is observed where google glass, electronic wrist bands, medical accessories, etc. are now overtaken by transparent, stretchable, and extremely light weight nanodevices capable of working under lower operating powers when placed conformably on human skin. Two-dimensional (2D) hybrid systems are the best choice for researchers when it comes to working towards developing transparent and stretchable hybrid devices capable of photodetection and random lasing. Lanthanides doped upconversion nanoparticles exhibit antistokes phenomenon owing to which when excited by lower energy photons, these emit photons of higher energies. The lanthanides comprises of a multi-energy level system that opens way for non-linear processes such as excited state absorption, energy transfer upconversion process, photon avalanche, etc. The multi-energy sublevels from the 4fn electronic configuration of lanthanides results in longer excited state lifetime for photogenerated charge carriers. This paves way for highly sensitive photodetection in 2D hybrid systems (e.g. upconversion nanoparticles/graphene hybrid). The multi-energy level system also provides for different metastable states suitable for the state of population inversion thus opening new ventures for fabricating lasing devices using upconversion nanoparticles. Research aims: 1. To design, fabricate and study transparent, wearable, broadband, and highly sensitive upconversion nanoparticles and graphene-based hybrid photodetectors. 2. To design, fabricate and study highly sensitive, visible blind, wearable, and omnidirectional near-infrared photodetectors.
3. To design, fabricate and study self-sufficient and highly efficient gold sandwich
upconversion nanocomposites lasers for stretchable and bio applications.
4. To design, fabricate and study Archimedean spiral rippled microstructures for
photodetection and random lasing.
The 2D hybrid systems comprising of upconversion nanoparticles and graphene were
successfully fabricated. Highly sensitive broadband and visible-blind narrow band
photodetection was observed from stretchable photodetectors comprising of upconversion
nanoparticles with different functionalities. Ultra-low thresholds random lasing action was
observed from upconversion nanoparticles sandwiched between gold nanoparticles upon
continuous wave 980 nm laser pumping. Random lasing actions were also observed from
upconversion nanoparticles when subjected to stretchable microstructures such as rippled
structures and the Archimedean spiral rippled microstructures. These devices with novel
designs make a significant contribution to the ongoing research in the field of stretchable and
human friendly optoelectronic devices. | en_US |