polymer compositeoled

Organic Photonic Materials • Nonlinear Optics Materials • Organic Light Emitting Diode (OLED) Nonlinear optics The interaction of electromagnetic fields with various media to produce new electromagnetic fields altered in • phase, • frequency, • amplitude from the incident fields • Second harmonic generation (SHG), the conversion of coherent light of frequency ω into light of frequency 2ω • The electro-optic effect allows one to change the refractive index of a material by simply applying a DC electric field to the material; thus, one can utilize the modulation of an electrical signal to activate an optical switch. • The polarization P induced in a molecule by a local electric field E P= αE + βE 2 +γE 3 + … α linear polarizability (the origin of refractive index) β second order hyperpolarizability (the origin of the second order nonlinear polarization response) Push-Pull in a Donor-Acceptor βValues of Some Organic Chromophores (10 -30 esu, 1064 nm) Charge Transfer Resonance Structures •First, the greater the charge separation in the charge transfer state (Dm), the larger the β •Second, the closer the frequency of the incident light is to the resonant frequency of the charge transfer, the larger the β Organic Electro-Optic Materials A Historical Perspective Statistical mechanical calculations suggested a new paradigm optimization of electro- optic activity: Control chromophore shape! N O NC CN NC N S O CN NC NC N O NC CN NC R' R' R R R R R R CLD-1 CLD-2 CLD-3 R = OTBDMS R=H FTC-1 R = OAc, R' = H FTC-2 R = OAc R' = CH 2 CH 2 CH 2 CH 3 R = H 0 20 40 60 80 100 120 140 0 20 40 60 No. Density (10^19/cc) CLD-2 CLD-3 Disperse Red (1995)→ For Bulk Materials P = χ (1) E + χ (2) E 2 + χ (3) E 3 + Fabrication of organic second order NLO materials • organic crystal growth, • inclusion complexes, • mono- and multilayered assemblies (e.g. Langmuir-Blodgett films), • poled polymers [...]... though these devices are better known as Polymer Light Emitting Devices (PLEDs) No vacuum is required, and the emissive materials can be applied on the substrate by a technique derived from commercial ink-jet printing • Recently a third hybrid light emitting layer has been developed that uses nonconductive polymers doped with light-emitting, conductive molecules The polymer is used for its production and... OLED: Small Molecules and Polymers • The first technology was developed by Eastman-Kodak and is usually referred to as "small-molecule" OLED The production of Small-molecule displays requires vacuum deposition which makes the production process expensive and not so flexible • A second technology, developed by Cambridge Display Technologies or CDT, is called LEP or Light-Emitting Polymer, though these devices.. .Polymer poling • The polymer is heated above the glass transition temperature and placed in a strong external electric field; this process is termed poling • The field serves to orient the chromophore with its dipole . complexes, • mono- and multilayered assemblies (e.g. Langmuir-Blodgett films), • poled polymers Polymer poling • The polymer is heated above the glass transition temperature and placed in a strong. Cambridge Display Technologies or CDT, is called LEP or Light-Emitting Polymer, though these devices are better known as Polymer Light Emitting Devices (PLEDs). No vacuum is required, and the. light emitting layer has been developed that uses nonconductive polymers doped with light-emitting, conductive molecules. The polymer is used for its production and mechanical advantages without