Download Final Presentation

csep.cnsi.ucsb.edu

Download Final Presentation

Fabrication of Light-Emitting DevicesUsing Polyelectrolyte FilmsGovinda EscobarMenteeAsanga RanasingheMentorProf. Steven BurattoFaculty AdvisorFunding Provided ByMC-CAM


Objectives of Research:‣To fabricate light-emitting devices using different polyelectrolyte films,Cd-Se quantum dots, and cathodes‣To study electroluminescent (EL) efficienciesStructure of DeviceGlassITO (anode)PPV [p-poly(phenylene vinylene)]PSS [poly(styrene sulfonate)]Cd-Se quantum dotAu/Ag/Ca/Mg (cathode)


Organic Electroluminescence‣Exciton formation at the organicheterojunction‣Exciton formation on the quantumdot layerHolesOxidationExcitonCd-SeLightElectronsReductionLight


Deposition of Polyelectrolyte Films‣Layer-by-Layer self-assemblypre-PPVPSSLbLPSS [poly(styrene sulfonate)]pre-PPV [poly(p-xylene tetrahydrothiophenium chloride)]ITO (anode)Glass


Conversion of pre-PPV to PPV*S +Cl- *T>120 o Cp = 10 -6 bar**Pre-PPVn>100PPV


Deposition of Cd-Se Quantum DotsThe Langmuir-Blodgett trough•Surface pressure for deposition is 30-35 mN/m 2•Langmuir-Schafer deposition technique used todeposit CdSe quantum dotsPressure-Area IsothermAirH2OS urface P ressure ( m N /m 2 )302520151050-5 50 70 90 110 130 150 170 190 210Area (cm 2 )


Studying Electroluminescence‣Current Density versus voltage isinvestigated‣Brightness versus voltage isinvestigatedNo electroluminescenceobserved:•Oxidation of quantum dotswith time•Dust particles caused ashort circuitModifications:•ZnS coating on quantumdots•Dust free environmentCurrent Density (mA/cm 2 )3530252015105Device 3AnodeLightCathode000 5 10 15 20Bias (v)0.50.40.30.20.1Brightness (cd/m 2 )


Feature Plans for Research:• To optimize the conditions for thefabrication of light-emitting devicesMy Accomplishments and Plans:• Realized my potential as a researcher• To return next summer as an intern in thesame research group• To obtain a PhD in physics


Acknowledgements:• MC-CAM• INSET• Prof. Steven Buratto• Asanga Ranasinghe• Buratto Research Group• Dr. James Kosmicki• My Family

More magazines by this user
Similar magazines