Energy harvesting will play a central role to offset the variability of renewable energy sources and achieve decarbonisation in global economies. Small-scale energy harvesters, in the W - mW range, are particularly attractive to increase the efficiency in energy conversion and storage operations of portable electrochemical devices [1]. Organic ferroelectric materials are excellent candidates as energy harvesters due to their flexibility, robustness and facile preparation, in comparison to zeolites and ceramics. Permanent polarisation in organic media, however, is limited to composites, such as poly(vinylidenefluoride)(s) and poly(trifluoroethylene)(s) [2].
In this project we will develop new organic energy harvesters containing ferroelectric liquid crystals stabilised by hydrogen-bonding. Liquid crystals form mesophases with short-range molecular mobility (which promotes conductivity), long-range order (which promotes ferroelectricity), and responsive character (to different energy sources).
We will control and optimise the ferroelectric behaviour of the new liquid crystals by:
-Preparing different liquid crystalline phases (columnar, smectic and twist-bend nematic).
- Introducing azobenzene groups to harvest light energy via trans-to-cis photoisomerization [3].
- Assembling different functional units by hydrogen-bonding [4] to yield dual transport via simultaneous n- and p-conduction [5].
In order to achieve our previous aims, we will complete the following tasks:
- Measure the dielectric properties of the new materials under strong electrical fields (20mV-200V) and high frequencies (1MHz-1GHz), using poly(vinylidenefluoride) and poly(trifluoroethylene) as reference materials.
- Characterise the phase behaviour of new liquid crystals containing benzoic acids and azobenzene groups, assembled by hydrogen-bonding.
- Determine the response of the materials to light/electrical fields:
- Ferroelectricity of the hydrogen-bonded liquid crystals will be measured by cyclic-voltammetry hysteresis and switching measurements, and broadband dielectric spectroscopy, in combination with UV irradiation.
- Piezoelectric force microscopy will be used to measure the electric response to pressure, and pyroelectricity will be controlled by the thermotropic behaviour of the liquid crystals and the temperature dependence of hydrogen-bonding [6].
- Flexoelectricity of liquid crystalline twist-bend nematic materials will be promoted by reorganisations of the helicoidal supra-structures upon strain gradients.
We envisage to obtain new light-responsive ferroelectric materials, controllable by external stimuli, hence applicable for energy conversion and storage, as sensors and actuators. In order to develop commercial applications, we will send selected liquid crystals to Dr Takashi Nakajima (Tokyo University of Science, Japan), who will prepare and evaluate new energy harvesting devices.
Selection will be made on the basis of academic merit. The successful candidate should have, or expect to obtain, a UK Honours Degree at 2.1 or above in chemical engineering, chemistry or physics. Experience on the following areas is advisable: Materials science, including concepts on electrochemical, mechanical and electrical characterisation; Fundamentals on chemistry and thermodynamics; Notions on conservation and transport phenomena (mass, energy); Fundamentals of polymer science and technology; Alternative energy technologies.
APPLICATION PROCEDURE:
Formal applications can be completed online: https://www.abdn.ac.uk/pgap/login.php
• Apply for Degree of Doctor of Philosophy in Engineering
• State name of the lead supervisor as the Name of Proposed Supervisor
• State ‘Self-funded’ as Intended Source of Funding
• State the exact project title on the application form
When applying please ensure all required documents are attached:
• All degree certificates and transcripts (Undergraduate AND Postgraduate MSc-officially translated into English where necessary)
• Detailed CV, Personal Statement/Motivation Letter and Intended source of funding
Continue with Facebook
