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SUMMARY:Breaking crystal symmetry – energy conversion with piezo/ferroel
 ectric materials
DTSTART:20141110T131500
DTEND:20141110T141500
DTSTAMP:20260511T065806Z
UID:ef4d18d2c1a7d1b62924a310eee72768d4522d1b8dcae17f31957838
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Steve Dunn\, Queen Mary University of London\, England\n
 In the last 10 years there has been growing interest in investigating the 
 impact of non-centrosymmetry of piezo or ferroelectric materials for energ
 y harvesting devices. The range of devices that are being investigated  i
 nclude those that can convert kinetic energy into electrical energy and th
 e conversion of sunlight into fuels\, known as solar fuels\, or produce el
 ectrical energy such as in a photovoltaic device. The fundamental principl
 e and area of most interest\, behind these energy conversion processes are
  related to the breaking of crystal symmetry that is found in a piezo or f
 erroelectric material. This breaking of the crystal symmetry intimately in
 fluences the physical properties within the material and leads to some ver
 y specific\, and analogous\, behaviour. In this talk I will show how the d
 omain structure of a ferroelectric material can effectively separate photo
 induced carriers. This leads to regio-specific photochemistry where oxidat
 ion and reduction occur on predefined areas of the photocatalyst surface\,
  separated by tens to hundreds of nanometres. I will then show how the dip
 ole of the ferroelectric crystal lattice can be used to produce enhanced p
 hotocatalytic efficiency and how these dipoles are possibly responsible fo
 r retarding the recombination of photoinduced carriers. We have recently m
 easured carrier lifetimes in BaTiO3 using transient absorption spectroscop
 y at 1-2 seconds without any external applied field. The same fundamental 
 phenomena is responsible for the 50% increase in power conversion efficien
 cy in a ZnO based photovoltaic device when music is played and also enable
 s us to effectively convert vibration into an electrical output. I’ll en
 d by drawing a picture of how the breaking of crystal symmetry may influen
 ce energy conversion in the future.\nReferences\nAcoustic enhancement of p
 olymer/ZnO nanorod photovoltaic device performance.\, Shoaee S\, Briscoe J
 \, Durrant JR and Dunn S. Advanced Materials vol. 26\, (2) 263-268.\nMeasu
 rement techniques for piezoelectric nanogenerators.\, Briscoe J\, Jalali N
 \, Woolliams P\, Stewart M\, Weaver PM\, Cain M and Dunn S. Energy and Env
 ironmental Science vol. 6\, (10) 3035-3045.\nEffect of ferroelectricity on
  solar-light-driven photocatalytic activity of BaTiO3 - Influence on the c
 arrier separation and stern layer formation.\, Cui Y\, Briscoe J and Dunn 
 S. Chemistry of Materials vol. 25\, (21) 4215-4223.\nSee what we are upto 
 - http://www.youtube.com/watch?v=nmn3LNAiNBA\nRead about what we do - New 
 Scientist\, Nov 7th\nHear what we do – Radio 4\, Inside Science (we are 
 at 10 mins)\nBio: I am part of the management team for the collaborative D
 octoral Training Centre that runs with Imperial College - www3.imperial.ac
 .uk/plasticelectronicsdtc - which enables students to undetake a wide rang
 e of PhD projects offered by either of the host institutions.\nIn my spare
  time I enjoy cycling and previously spent a good deal of time sailing\, w
 hich I did upto European level\, winnning a UK National Championships in 2
 003 and placing top 3 in various European events. Through sailing I obtain
 ed full blues from Edinburgh and Cambridge Universities and learnt alot of
  valuable transferable skills\, by helping support and volunteering my tim
 e at clubs and coaching other sailors. I also love being outdoors either i
 n the garden growing as many variety of chillis as I can or climbing up a 
 mountain.
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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