Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/35231
Title: Graphene Based Composites for Light Harvesting Applications
Authors: KIRAN KUMAR MANGA
Keywords: Graphene, nanocrystals, photodetector, photocurrent, nonvolatile memory, opto-electronic memory
Issue Date: 31-Jan-2012
Source: KIRAN KUMAR MANGA (2012-01-31). Graphene Based Composites for Light Harvesting Applications. ScholarBank@NUS Repository.
Abstract: The multifunctional properties together with the ease of processibility render graphene-based materials highly useful for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In the first part of this thesis, the fundamentals of graphene electronic and optical properties are discussed followed by introducing organic-inorganic composites of graphene (G) or graphene oxide (GO) preparation methods and their applications in light harvesting applications. In the second chapter of this thesis, multilayer assembled films consisting of titania and graphene oxide sheets followed by photocatalytic reduction to study the electron transfer dynamics and photoelectrochemical properties. Hybrid films enhance the photocurrent conversion due to effective charge separation and improved percolation pathways. In Chapter 3, a strategy developed based on TiO2-GO ionic hybrid precursor to fabricate printable photodetector with high sensitivities. The device achieves high gain and switching speed due to cooperative distribution of photogenerated charge carriers through TiO2-G photoconducting matrix. To address the problem associated with solution dispersability of colloidal quantum dots, a novel in-situ deposition of quantum dots on electrochemically exfoliated graphene sheets has been developed in chapter 4. multiphase assembled photoconductor hybrid based on few layer graphene (FLG), PbSe and TiO2 such as FLG/PbSe/TiO2 have been prepared and printed on flexible substrates to achieve flexible photodetector device. Photothermal deflection spectroscopy (PDS) studies made on hybrid films to study the week sub-band absorptions and charge transfer bands. The hybrid photodetector device achieves superior gain and detectivities due to cooperative role of individual components. In the last part of this thesis, nonvolatile memory device fabricated using Tetracene-GO organic wire hybrid and tested. Highly robust write-read-erase cycles achieved with high ON/OFF ratio. Also by integrating the photoactive hybrid (PbSe/G) with dielectric Polymer, optoelectronic memory device fabricated and characterized. The hybrid device achieves relatively enhanced memory characteristics compare to control devices.
URI: http://scholarbank.nus.edu.sg/handle/10635/35231
Appears in Collections:Ph.D Theses (Open)

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