114 CMDITR Review <strong>of</strong> Undergraduate Research Vol. 2 No. 1 Summer <strong>2005</strong>
Electroluminescent Properties <strong>of</strong> Organic Light-Emitting Diodes (OLEDs)with 2,5-Bis(9,9-dimethylfluoren-2-yl)-1,1,3,4-tetraphenylsiloleEvans ThompsonGeorgia Institute <strong>of</strong> TechnologyBenoit Domercq and Bernard KippelenSchool <strong>of</strong> Electrical and Computer EngineeringGeorgia Institute <strong>of</strong> TechnologyA new organic compound, 2,5-Bis(9,9-dimethylfluoren-2-yl)-1,1,3,4-tetraphenylsilole(DTS), derived from the silole family has been electroluminescently characterized. Functionalorganic light-emitting diode (OLED) devices were fabricated using DTS as electrontransportlayer (ETL), hole-transport layer (HTL), emission layer (EML), and single layer(SIL). DTS was found to be a bright green emitter with a peak wavelength <strong>of</strong> 535 nm anda maximum half life <strong>of</strong> 4000 s.Background <strong>of</strong> OLEDs in high resolution displaysThe demand for high resolution large area flat panel displaysis large. Liquid Crystal Displays (LCDs), the leading flat paneldisplay technology, hold that title because <strong>of</strong> their long life <strong>of</strong>operation, light weight, low operation costs and brightness. However,LCDs are not without their disadvantages. LCDs require abacklight, causing low contrast ratios due to an inability to producea true black image. Additionally, LCDs are expensive, especiallyfor displays exceeding 30 inches, and have low viewingangles.A new display technology using OLEDs, has the potential tosupplant LCDs as the leading display technology. OLEDs convertelectricity directly into light. By creating their own light these deviceswill require no backlighting, reducing the operating powerrequirements. They will be very efficient and have low operatingcosts. The organic materials are inexpensive and the actualfabrication <strong>of</strong> large displays will be cheaper than large LCDs. Inaddition, flexible displays can be made with OLEDs since they donot require a rigid substrate.Currently OLED displays still have a few hurdles to overcomebefore they make their way to the living room. The efficiencyand lifetime <strong>of</strong> the organic compounds are still too low, andfabrication is still too expensive. Researchers have been workingto find new compounds with high efficiencies and longer lifetimesas well as new OLED fabrication techniques.Background <strong>of</strong> siloles Siloles, or silacyclopentadienes, areSi-containing five-membered cyclic dienes with conjugate ringshaving different structures attached.[1,2] The highest externalquantum efficiency (EQE) for a singlet emitting OLED is between1.1 and 1.5% for a TPD-Alq 3OLED device. While for asilole the maximum EQE is roughly three times that <strong>of</strong> TPD-Alq 3OLEDs, due to its 100% photoluminescent efficiency [ 3 ]. Silolesalso have a low electron affinity (EA) comparable to that <strong>of</strong> Alq 3,a widely used electron transport material. DTS, in particular, hasan Ionization potential comparable to that <strong>of</strong> TPD, an organiccompound used for hole-transport. Figure 1 shows the chemicalstructure <strong>of</strong> DTS.Figure 1. Chemical structure <strong>of</strong> 2,5-Bis(9,9-dimethylfluoren-2-yl)-1,1,3,4-tetraphenylsilole (DTS).Device StructureThe devices consist <strong>of</strong> multiple layers <strong>of</strong> organic and inorganiccompounds. The layers are deposited on an Indium TinOxide (ITO) coated glass slide using high vacuum physicalvapor deposition (PVD). PVD is a deposition technique wherethe material is vaporized by heating to condense on a substrateforming a uniform thin film.The glass slides went through 4 stages <strong>of</strong> ultra soniccleaning in which they were submerged in soap water, deionizedwater, acetone and ethanol. The slides were then bakedin a vacuum oven to remove any left over ethanol. Silicon oxidewas then deposited on the slides and again ultrasonicallyCMDITR Review <strong>of</strong> Undergraduate Research Vol. 2 No. 1 Summer <strong>2005</strong> 115
- Page 2 and 3:
The material is based upon work sup
- Page 4 and 5:
TABLE OF CONTENTSSynthesis of Dendr
- Page 6 and 7:
6 CMDITR Review of Undergraduate Re
- Page 8 and 9:
SYNTHESIS OF DENDRIMER BUILDING BLO
- Page 10 and 11:
throughout the work period. Five su
- Page 12 and 13:
12 CMDITR Review of Undergraduate R
- Page 14 and 15:
BARIUM TITANATE DOPED SOL-GEL FOR E
- Page 16 and 17:
BARIUM TITANATE DOPED SOL-GEL FOR E
- Page 18 and 19:
SYNTHESIS OF NORBORNENE MONOMER OF
- Page 20:
20 CMDITR Review of Undergraduate R
- Page 23 and 24:
using different reaction conditions
- Page 25 and 26:
Synthesis of Nonlinear Optical-Acti
- Page 27 and 28:
quality of the XRD structures wasca
- Page 29 and 30:
Behavioral Properties of Colloidal
- Page 32 and 33:
Transmission electron microscopy ha
- Page 34 and 35:
34 CMDITR Review of Undergraduate R
- Page 36 and 37:
areorient themselves with the elect
- Page 38 and 39:
Fabry-Perot modulators with electro
- Page 40 and 41:
40 CMDITR Review of Undergraduate R
- Page 42 and 43:
QUANTIZED HAMILTON DYNAMICS APPLIED
- Page 44 and 45:
44 CMDITR Review of Undergraduate R
- Page 46 and 47:
INVESTIGATING NEW CLADDING AND CORE
- Page 48 and 49:
Dr. Robert NorwoodChris DeRoseAmir
- Page 50 and 51:
SYNTHESIS OF TPD-BASED COMPOUNDS FO
- Page 52 and 53:
SYNTHESIS OF TPD-BASED COMPOUNDS FO
- Page 54 and 55:
OPTIMIZING HYBRID WAVEGUIDESpropaga
- Page 56 and 57:
At closer spaces the second undesir
- Page 58 and 59:
SYNTHESIS AND ANALYSIS OF THIOL-STA
- Page 60 and 61:
60 CMDITR Review of Undergraduate R
- Page 62 and 63:
QUINOXALINE-CONTAINING POLYFLUORENE
- Page 64 and 65: QUINOXALINE-CONTAINING POLYFLUORENE
- Page 66 and 67: 66 CMDITR Review of Undergraduate R
- Page 68 and 69: SYNTHESIS OF DENDRON-FUNCTIONALIZED
- Page 70 and 71: 70 CMDITR Review of Undergraduate R
- Page 72 and 73: BUILDING AN OPTICAL OXIMETER TO MEA
- Page 74 and 75: 74 CMDITR Review of Undergraduate R
- Page 76 and 77: 76 CMDITR Review of Undergraduate R
- Page 78 and 79: TOWARD MOLECULAR RESOLUTION C-AFM W
- Page 80 and 81: TOWARD MOLECULAR RESOLUTION C-AFM W
- Page 82 and 83: SYNTHESIS AND CHARACTERIZATION OF E
- Page 84 and 85: My name is Aaron Montgomery and I a
- Page 86 and 87: 1,1-DIPHENYL-2,3,4,5-TETRAKIS(9,9-D
- Page 88 and 89: 1,1-DIPHENYL-2,3,4,5-TETRAKIS(9,9-D
- Page 90 and 91: EFFECTS OF SURFACE CHEMISTRY ON CAD
- Page 92 and 93: EFFECTS OF SURFACE CHEMISTRY ON CAD
- Page 94 and 95: 94 CMDITR Review of Undergraduate R
- Page 96 and 97: SYNTHESIS OF A POLYENE EO CHROMOPHO
- Page 98 and 99: SYNTHESIS OF A POLYENE EO CHROMOPHO
- Page 102 and 103: 102 CMDITR Review of Undergraduate
- Page 104 and 105: CHARACTERIZATION OF THE MOLECULAR P
- Page 106 and 107: 106 CMDITR Review of Undergraduate
- Page 108 and 109: OPTIMIZATION OF SEMICONDUCTOR NANOP
- Page 110 and 111: OPTIMIZATION OF SEMICONDUCTOR NANOP
- Page 112 and 113: CHARACTERIZATION OF THE PHOTODECOMP
- Page 116 and 117: ELECTROLUMINESCENT PROPERTIES OF OR
- Page 118 and 119: 118 CMDITR Review of Undergraduate
- Page 120 and 121: DETERMINATION OF MOLECULAR ORIENTAT
- Page 122 and 123: DETERMINATION OF MOLECULAR ORIENTAT
- Page 124 and 125: HYDROGEL MATERIALS FOR TWO-PHOTON M
- Page 126 and 127: HYDROGEL MATERIALS FOR TWO-PHOTON M
- Page 128 and 129: THE DESIGN OF A FLUID DELIVERY SYST
- Page 130: THE DESIGN OF A FLUID DELIVERY SYST