ProfessorGirish Lakhwani

Project Opportunities

Title: Chiroptical phenomena of pi-conjugated materials

Summary of opportunity:

pi-conjugated materials are organic molecules with alternate single and double bond character that provide for their semiconducting properties. For example, pi-conjugated polymers (CPs) have proven to be cheap, easily processible and flexible alternatives to silicon for sustainable energy applications like thin film solar cells and light emitting diodes. However, the optical and electronic properties of these materials depend strongly on the polymer structure organization within thin films. These materials can self-assemble into ordered supramolecular stacks, cholesteric liquid crystals, or can form disordered collapsed structures depending on processing conditions. Structure-property relationships in these materials are very complicated and not well understood. In this project, we will use chirality as a probe in the side-chains of conjugated materials to probe the relationship between their different morphologies and optical properties using Circular Dichroism (CD) spectroscopy.

Opportunity synopsis:

Circular Dichroism (CD) spectroscopy is often used to study molecular organization of chiral materials by measuring difference in absorbance of left- and right- circularly polarised light. CD experiments on chiral conjugated materials provide us with morphological information on intermolecular packing and relative orientation between molecules which otherwise are undetectable using conventional optical techniques. In the course of project, the PhD student will use UV-Vis Absorbance, Fluorescence and CD spectroscopy to characterise ground state properties of chiral molecules both in solutions and spin-coated thin films. The student will use surface techniques such as AFM, TEM and confocal microscopy at the ACMM to image the surface morphology of thin films. The student will develop and/or extend the optical setup capable of studying excited state properties, such as circularly polarised luminescence (CPL). A challenging endeavour will be to use the morphological information in fabrication and optimisation of organic solar cells.

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Project Opportunities

Title: Faraday Rotation in Organic Semiconductors

Summary of opportunity:

Society's over-reliance on information exchange around the world hinges critically on ultrafast data communication using light signals.  Modern optical data communication works at high bit rates and therefore polarisation switches have to be very fast (<1ns).  Understanding dynamics of polarisation decay and dispersive transport of excitons as a function of device morphology is critical in underpinning material parameters required developing ultrafast polarisation switches.  This project will use a range of complementary experimental approaches to study polarisation switching and Faraday rotation in an emerging class of organic semiconductors.

Opportunity synopsis:

This research project intersects physical chemistry, material science and chemical physics.  Students will investigate optical properties of π?conjugated materials using polarised light spectroscopy such as Circular Dichroism, Optical Polarimetry, and Cicularly Polarised Luminescence.  A more challenging part of the project will be to develop cutting-edge methodologies to allow for investigation of time-resolved excited state properties sensitive to polarised light.

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Project Opportunities

Title: Strong light-matter coupling based optical computing

Summary of opportunity:

Optical computing devices and neural networks are inherently capable of tackling pattern recognition tasks and handling big data, which are essential for artificial intelligence. Nonetheless, using photons to achieve efficient computation continues to be a significant challenge. Photon-photon interactions are considerably weaker and necessitate high intensities, significantly restricting their applicability in optical computing components such as switches and transistors.

Light can strongly couple with organic semiconductor molecules and materials at room temperature, forming exciton-polaritons that are quasiparticles with both light and matter properties. Polaritons can substantially modify excited energy states and display nonlinear optical characteristics. Interparticle interactions in exciton-polaritons can be orders of magnitude greater than weakly interacting photons, making them exceptional candidates for optical computations. In this project, you will experimentally investigate and utilise exciton-polaritons for efficient optical computations. The project provides opportunities to concentrate on devices or spectroscopy in collaboration with theorists, experimentalists, and our industry partners.

Opportunity synopsis:

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Project Opportunities

Title: Chiral nano-optics

Summary of opportunity:

Telecommunications networks use light signals transmitted through fibre to quickly transfer information over long distances and electronic circuits to process and store the data. Breakthrough technology in modern information transmission networks can be attained through all-optical switches. These switches use light-encoded data as a medium for optical switching, eliminating the need for relatively slow and error-prone electronic circuits susceptible to heat. All-optical switches use nonlinear interactions between photons. Second-order nonlinear effects are highly symmetry-specific, i.e., they require a material to be non-centrosymmetric. Chiral materials inherently fall into this category, making them an intriguing class of materials to examine for nonlinear properties.

In this project, you will experimentally investigate the nonlinear optical and chiroptical properties of hybrid semiconductors, including chiral metal-organic frameworks and perovskites, using advanced spectroscopic techniques. The focus will be on their applications in all-optical switches and sensors. You will have opportunities to collaborate with synthetic chemists and device physicists.

 

Opportunity synopsis:

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Project Opportunities

Title: Chiral nano-optics

Summary of opportunity:

Telecommunications networks utilise light signals transmitted through fibre optics to efficiently transfer information over long distances. They rely on electronic circuits for data processing and storage. A significant advancement in modern information transmission networks is the development of all-optical switches. These switches handle light-encoded data, eliminating the reliance on slower and more error-prone electronic circuits that are vulnerable to heat. All-optical switches operate using nonlinear interactions between photons. Second-order nonlinear effects are particularly symmetry-specific, requiring materials to be non-centrosymmetric. Chiral materials meet this criterion, making them a fascinating class of materials for exploring nonlinear properties.

In this fundamental research project, you will experimentally explore the magneto-optical and chiroptical properties of hybrid semiconductors using both steady-state and time-resolved advanced spectroscopic techniques. The primary goal is to discover new optical phenomena that can be utilised in all-optical switches, taking advantage of the optical, electronic, and spin properties of the materials. You will have the opportunity to collaborate with synthetic chemists and device physicists.

The successful candidate will conduct experimental work in Prof. Girish Lakhwani's research group in the School of Chemistry. For more information, please visit the group website or contact Prof. Lakhwani.

Opportunity synopsis:

----------Current Research Projects----------

_x000D_ Directing light-matter interactions for optical encryption

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_x000D_ Strong light-matter coupling based optical computing

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_x000D_ Chiral Nano-optics