OLED ߱ ̿ ֽϴ. , ذ . ؿ , ؿ ڵ ˴ϴ. ذ Ǵ ȭҰ . ذ ̿ ϴ ⸷ ġ Ǿ ֽϴ. ذ ۿ 캸, ֻ Ī TFT Ʈ ΰǸ, ȣ Ʈ TFT Ʈ ɸ ˴ϴ. ȣ а ä а Ȥ Ǹ鼭 OLED ؿ 帣 ϰ .
•OLED, ij ̵, , ߱
•OLED, ,
•OLED, ,
•OLED, ,
OLED, ij ̵, , ߱ >>
ݵü յ ܰ ڵ Ǿ ־ 带 Ͽ ڴ ǵ, ݵü ڵ ߽ ټ ϰ Ǿ ֽϴ. ̻(discrete) ˵ ־ ڰ ϰ ġ ˵ Լ LUMO(Lowest Unoccupied Molecular Orbital) ϰ, ڰ ϰ ġ ˵ Լ HOMO(Highest Occupied Molecular Orbital) ǥմϴ. ݵü ̵ ڴ뿡 شϴ .
ٸ, ݵü 뿡 ġ ڵ ϴ Ӱ 帣, ݵü ڵ ̻ Ǿ ִ HOMO ġ ¡˴ٸ dzʰ ٱ(hopping) ϸ ̵մϴ. , ħ ߱ LUMO ִ ڵ HOMO 鼭 .
̵ . ڴ ĵε ǥ ִ Դϴ. ڸ . ݵü ݵü 뿡ŭ ο ڴ ϴ. ̵Ϸ ĵ ĵ (phonon, ) (electron-phonon coupling) ̷, ĵ ְǰ Ǹ鼭 ǰ ̷ϴ. а еǸ, LUMO HOMO ̿ ٸ մϴ. ̵ ϹǷ ڵ ̸ . ᱹ ڰ ִ ڸ յ п شմϴ. ̷ а , (exciton) Ǿٰ . ģ ¿ LUMO ó ӹ , ڰ HOMO ó ִ , ڸ ߱ ̷ϴ.
̷ 鿡 ؼ ϵ ϰ, ڿ ̵, , ̶߱ ۵ ϵ ϰڽϴ. , ذ κ Ե ڿ ̵ϸ鼭 ߱ ̸ ǰ, ڿ Ͽ . ڿ ġ ö 庮 ö ߱ մϴ. ߱ 庮 Ǿ ᱹ ڿ ߱ ȿ ӹ ȸ . , ̷ ۵ ⱸ ϵ 谡 ˴ϴ. ذ õ ϳ ̾ ڽϴ.
OLED, , >>
OLED ߱ ̿ ֽϴ. , ذ . ؿ , ؿ ڵ ˴ϴ. ذ Ǵ ȭҰ . ذ ̿ ϴ ⸷ ġ Ǿ ֽϴ. ذ ۿ 캸, ֻ Ī TFT Ʈ ΰǸ, ȣ Ʈ TFT Ʈ ɸ ˴ϴ. ȣ а ä а Ȥ Ǹ鼭 OLED ؿ 帣 ϰ . , ؿ , ؿ ڵ OLED η ˴ϴ. Ʈ, 巹ΰ ҽ ΰǴ ؼ OLED 帣 TFT n p, OLED , Ȥ (inverted) ο ٲ , ⺻ 뵿մϴ.
ij ڵ OLED η Ͽ ִ ϹǷ, ⺻ ij η Ͽ Ѿ߸ ϴ 庮, ؿ ̾ ⸷ 鿡 庮 ̰ ƾ . ̸ Լ(work-function) , 簡 ʿմϴ. ٸ, 庮 ٰ ̳ʽ Ǹ ȵ. ΰ ʾƵ ij η ȵǴϱ. Ͽ Ϲ Ǵ ϹǷ Ͽ մϴ. , Ͽ ߱ OLED, ذ ϴ OLED ̷ Ϻ ǰ ֽϴٸ. ̿ Բ, ϰ, Ǵ Ͽ մϴ. ϸ, OLED ij, , ڿ ̳ʽ ƴ 庮 ̰ ƾ ϸ, Ͽ Ѵٰ ֽϴ.
Ϲ Ͽ߸ ϴ , ITOܿ Ư Ƿ, ITO Լ ̱ , 庮 ߱ ҳ ö ó ϱ մϴ. , ITO Լ 4.6~5.0eV ε ö ó Ͽ 5.2 ~ 5.4 eV . ̿ Բ ̱ ITO β 100 ~ 150 ϸ, ñ 90% ̻, 10 Ω/sq. ʿմϴ. ITO ̿ δ ε ƿ ȭ(Indium Zinc Oxide, IZO)̳ SnO2 Ϻ ǰ ֽϴ. ݸ鿡 κ ο 쿡 Լ ϸ 庮 ֽϴ. , Լ Al, Ca, Li, Mg ϸ, ̵ ݼ Լ 뷫 2.4 ~ 4.3 eV Դϴ. ̵ κ ݼ̹Ƿ Ȯ (Ag) Բ ϱ մϴ. Ag ϸ, ñ ݻϿ ȿ .
̿ Ͽ, , Ϻ ġϱ ϸ, , ʷ, Ķ, 3 ϰų, OLED ο ġǴ ֽϴ. , Ǵ ǥ źȭ ſ ߿. ǥ ź , ذ , ذ Ÿ ߵǰ, 帣 Ǿ ȭ ϱ մϴ. ؿ ̼ (pin hole)̳ (crack), Ȥ ذ ٷ Ʒ 鿡 ƴ ϸ, ҳ Ⱑ ħϴ ǰ, ̷ Ͽ ϴ (dark spot) մϴ.
OLED, , >>
OLED п ڸ մϴ. , ⸷ ñ ǥ 鿡 庮 ߾ ϰ Եǰ, 鼭 ϵ ӵ µ ߱ Ǵ . ̷ Ϲ ݵü ū ڿ ̵ ſ ٴ Դϴ. ݵü , ̵ 1 1,000/Vs ݸ鿡 ݵü 10 1 10-7 10-3/Vs ؿ Ұմϴ. ΰ п ϴ ؼ β ƾ . κ Ե ij Ǵ (Electron or Hole Injection Layer, EIL or HIL), Ȥ κ ϵ ϵ ִ մϴ. ص Լ ų Ȥ Ͽ ڳ 鿡 鿡 Ǵ 庮 ߰ . 庮 ߴ ҵ ߿մϴ. , ȭ Ƭ(Lithium Fluoride, LiF) ݼ ҷΰ ȭչ(metal halide) 2(interface electric double layer) , ̵ Ű鼭 庮 ߴ ˷ .
κ (Ȥ ) ԵǴ δ ֽϴ. , ڰ 庮 Ѵ ̴ ſ ū ʿ ϸ, 庮 ̰ 3.0 eV ̻ Ǹ ĸδ ϱⰡ ư ˴ϴ. °δ ⸷ 迭 , , ̵ ó ö鼭 Ѿ Բ . °δ ذ ΰǾ 庮 β ϸ鼭 ڵ 庮 հ(tunneling) ϴ Դϴ. 쿡 ʰ . κ Ȥ ̷ Բ ۿǸ鼭 մϴ. ̷ Ե ij Ϸ ϴ Ϸ Ŀ Ǹ б ϸ, ̵ Ϸ ۿϿ 帧 ϱ . , (Space Charge Limited Current, SCLC) ߱˴ϴ. , ij Կ ־ ذ Ư ߿ϸ, ̸ Ͽ Ȥ Ǿ մϴ.
Ϲ 庮 ߱ Ǹ, HOMO Լ HOMO ̿ ġմϴ. , ߱κ ̱ Ŀ ñ Ḧ . ʱ 5.0eV HOMO CuPc(copper(II) phthalocyanine) ŻνþƴѰ ȭչ Ǿ, ñ ̱ HOMO 5.1eV ó m-MTDATA(Tris[phenyl(m-tolyl)amino] triphenylamine), Ȥ LUMO 5.5eV HAT-CN(Hexaazatriphenylenehexacarbonitrile) õǾϴ. Ư HAT-CN ֱڸ ϰ ν ߰ ȿ ̴ ȿ ִ Ǿϴ. ̿ Բ δ PEDOT:PSS(poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) ǥ ǰ ֽϴ.
, κ ڵ ԽŰ մϴ. Ϲδ Į ݼ ִµ ̴ ҳ а . ǥδ LiF, CS2CO3 ȭչ Ǹ, ū Դϴ. ̵ β 0.5 ~ 2 ϸ Ϻ ϰ ͳθ Ͽ Ư Ǵ ȿ ϴ. ̷ 庮 翬 ذ ̿ ġϿ . ̿ Ͽ, , ȭ ʾƾ ϸ, ذ , ź Ͽ մϴ. , ð ŷڼ ⸷ ⺻ Դϴ.
OLED, , >>
ؿ Ͽ ϵ, ڳ Ȱϰ ߱ ̵ϰ ϸ, ̿ Ͽ ϵ () ұ ϴ 쵵 ֽϴ. ⺻ ϵ ̵ , 庮 ٴ , ߱ ٴ Ǿ . ݸ鿡 ε Ϸ ϵ鿡 ؼ ߱ٵ 庮 Ͽ ߱ ȿ δ ҵ Ͽ մϴٸ, ⼭ ٷ ϰ ҿ ؼ ̾ϴ. κ ߱ ϸ, HOMO ߱ HOMO ߰ ġϿ մϴ. ̵ ƾ ϸ, µ ϴ. ߱ ϹǷ ߱ 鿡 ڵ鰣 ȣ ۿ, Ư Ͼ ʾƾ . ַ ƮҾƹΰ TPD(triphenyl-diamine derivative) Ǹ, Ư µ ̱ ƮҾƹ ⺻ ڸ ϴ ̿˴ϴ. ̿ Ͽ ߱ Ͽ ߱ ū ߸ .
, ڵ κ ߱ ϸ, LUMO ߱ ߰뿡 ġϿ մϴ. ̵ µ ƾ մϴ. ߱κ ʱ Ͽ ߱ Ŀ . ڵ ۿ⸦ ȭչ, Ǹ, Ʈ̾ մϴ. ڸ Ÿ ʵ Ư¡ Ͽ ϸ, µ, ð Բ β, ߱ Ư ʼ ˴ϴ.
<ȣ ̾ >
“ ְ ظ ϰ , ο ڷ پϿ ǥ , ٶϴ.”
<۱ڨ 'öƽ̾' - .>
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