Hans U. Güdel Department für Chemie und Biochemie

Seminar Fribourg, 13.10.2009

Making light

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Making light

3

Area illuminators

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OLED Technology

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• Light• White and coloured light• Photoluminescence, phosphors• Spectrum• Light emitting diodes (LED) • Outlook

Making light

• Light

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• Light

Making light

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Fiat Lux

1 in principio creavit Deus caelum et terram

2 terra autem erat inanis et vacua et tenebrae super faciem abyssi et spiritus Dei ferebatur super aquas

3 dixitque Deus fiat lux et facta est lux

4 et vidit Deus lucem quod esset bona et divisit lucem ac tenebras

First Book Moses (Genesis), Chapter 1

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Black body radiation

Temperature: Colour:

2500°C

5000°C

7500°C

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Black body radiation

Temperature: Colour:

5000°C

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Human eye photoreceptors

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Incandescent lamp

2500°C

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Dispersion of white light

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Making light: Additive mixing

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Chromaticity Diagram

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Photoluminescence

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Kasha's Rule

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Light emitting semiconductor

Light emission

Conduction band

Valence band

+

–

Bandgap

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Photoluminescence of CdSe Nanoparticels

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Fluorescent lamp

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Luminescent phosphors

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Lamp and display phophors

BaMgAl10O17: Eu2+

(Ce,Gd)MgB5O10: Tb3+

Y2O3: Eu3+

Judith Grimm

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The Lanthanides

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Coloured light

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LED based technology

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Light emitting diodes (LED)

Electroluminescence

Conduction band

Valence band

+

–

Bandgap

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LED Materials

Inorganic

III – V Semiconductors

Al, Ga, In N, P, As, Sb

Al Ga As

Al Ga In P

Al Ga P

Ga N

Organic (OLED)

Polymeric luminescent molecules with conjugated electron systems

Polyphenylenvinylene

n

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Light emitting polymer

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Mirco Colombo citations, 3 papers

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Diode spectra

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White diode lamp

Y3Al2(AlO4)3: Ce3+ Diode

+

–

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Chromaticity Diagram

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Energy efficiency of light sources

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Light sources

Technology steps

Electronics

Tube

analog

Tube Diode

Solid

Micro electronics

digital, solid

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Area illuminators

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Acknowledgment

Gabriela Frei