conductivityvovokan

KanchanaWeerakoon5/01/06PhotoemissionstudiesofpolythiopheneandpolyphenylfilmsproducedviasurfacepolymerizationbyIonassisteddepositionAbstractConductivityofamaterialisdependantonitselectronicstructure.
Thedifferenceintheenergybetweenthehighestoccupiedmolecularorbital(HOMO)andthelowestunoccupiedmolecularorbital(LUMO)isknownasthebandgap.
Thelowerthebandgap,highertheconductivityofamaterial.
Polymersconsistingofaconjugatedbackboneareconductivewhendopedappropriately.
IfapolymerchainhasNnumberofatomsseparatedbyadistanced,thechainlengthisgivenas(N-1)d.
TheparticleinaboxmodelcouldbeusedtodeterminetheenergylevelsHOMO,LUMOandthebandgap.
Accordingtoonedimensionalparticleintheboxmodel,wheren=1,2,3…isthequantumnumber,mistheelectronmassandhistheplankconstant.
Thebandgapdecreasesasthepolymerlengthincreases.
Inthisstudy,conductingpolymerfilmsweregraftedonasurfaceusingionassisteddeposition(SPIAD)todepositnovelpolythiopheneandpolyphenylthinfilmsbyhypothermalselectionthiophenecationsα–terthiophene(3T)andp-tertphenyl(3p)neutrals.
Theelectronicstructureofthesefilmswasanalyzedusingpolarizednear-edgeX-rayabsorptionfinestructurespectroscopy(NEXAFS)andultravioletphotoelectronspectroscopy(UPS)andwascomparedwithsimilarevaporatedfilms.
TheSPIADmethoddisplaysareductioninbandgap,resultedfromanincreaseintheconjugationlengthandotherchangesinthefilmstructure.
MainReference:TepavcevicS.
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Phys.
Chem.
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