元件的結構與製作

ITO pattern 之製作模式如第二章所示，而發光元件之結構，陽極仍為 ITO，並塗佈一層 PEDOT 來作為電洞注入層及修飾層。發光層的製作則分 別將 Pt-Fluorene 錯合物和 poly(N-vinylcarbazole) (PVK) 和(2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) 以 1.5 mg : 14 mg : 6 mg 的比例 均勻混合溶於氯苯( chlorobenzene )溶劑中，直接以旋轉塗佈之方式製作而 成，陰極之選擇則為蒸鍍一層 100 nm 鋁金屬，最後再以玻璃配合 UV 乳膠

Lu mi na n c e ( c d /m

2

) Yield (cd/A)

Voltage (V)

Fig. 3-48. Luminance-yield-voltage curves for the devices of Pt complex.

0 50 100 150 200 250

0 5 10 15 20 25 30

Curren t den s ity (m A/cm

2

)

Voltage (V)

Fig. 3-49. Current-voltage curve for the devices of Pt-Fluorene complex.

400 450 500 550 600 650 700 750 800

Inte nsity (a.u .)

Wavelength (nm)

Fig. 3-50. EL spectrum for the devices of Pt-Fluorene complex.

3.10.3 電荷深層能階瞬間光譜儀 (Q-DLTS) 研究

現三個不同的波峰，分別標示為Peak I、Peak II和Peak III，分解的圖譜顯 示於Fig. 3-52，由此可知至少有三種不同的陷域型態在此元件中。另外，

在釋放時間log τ_m < 2 的地方有一個小波峰，由於釋放時間太短，因此無法 對其作更一步的研究。Fig. 3-53 表示在溫度 270-330 K範圍以及△V = + 6V 下的圖形變化，從不同溫度下的波峰數值，再利用第二章所提到的公式 ( 3 ) ，將-ln(τT²)和 1/KT作圖，即可將各波峰活化能EA和俘獲交錯區域σ計 算出來。Fig. 3-54、3-55 和 3-56 分別為Peak I、Peak II和Peak III隨溫度變 化的波峰圖，而計算的arrhenius圖形則整理並表示於Fig. 3-57 中。Peak I的 活化能為 0.33 eV，俘獲交錯區域σ為 4×10^-21 cm²，Peak II的活化能為 0.4 峰，分別標示為Peak I 、Peak III、Peak IV和Peak V，其分解的圖譜如Fig.

3-59 所示。其中Peak I 和III是來自於PVK+PBD的系統中，而Peak IV 和 Peak V則是屬於Pt錯合物的陷域。Fig. 3-60 表示在溫度 270-330 K範圍以及 充電時間為 1s和△V = + 6V下的圖形變化，Fig. 3-61 到 3-64 分別為Peak I 、Peak III、Peak IV和Peak V隨溫度變化的波峰圖，經過相同的計算方

式，每一個peak的arrhenius圖形表示於Fig. 3-65 中，而各個陷域的參數整

Fig. 3-51.Q-DLTS spectra measured on a ITO/PEDOT:PSS/PVK+PBD/Al device using a charging voltage ΔV = + 6V for different charging time from 1 ms to 1 s at T=300 K.

0

Fig. 3-52. Resolved Q-DLTS spectra measured on a ITO/PEDOT:PSS/

PVK+PBD/Al device using a charging voltage ΔV = + 6V for charging time 1 s at T=300 K.

Fig. 3-53. Q-DLTS spectra measured on a ITO/PEDOT:PSS/PVK+PBD/Al device in using a charging time τ_c = 1s and a charging voltage ΔV = + 6V for different temperatures in the range 270-330 K.

0 1000 2000

0 1 2 3 4 5 6 7 8

Δ Q (pC )

log(t) (t: us)

270 K 330 K

Fig. 3-54. Peak I obtained from the Q-DLTS spectra recorded in a ITO/

PEDOT:PSS/PVK+PBD/Al diode for different temperatures in the range 270 - 330 K with a charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

0 1000 2000

0 1 2 3 4 5 6 7 8

Δ Q (pC )

log(t) (t: us)

270 K 330 K

Fig. 3-55. Peak II obtained from the Q-DLTS spectra recorded in a ITO/

PEDOT:PSS/PVK+PBD/Al diode for different temperatures in the range 270 - 330 K with a charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

0 1000

0 1 2 3 4 5 6 7 8

Δ Q (pC )

log(t) (t: us)

270 K 330 K

Fig. 3-56. Peak III obtained from the Q-DLTS spectra recorded in a ITO/

PEDOT:PSS/PVK+PBD/Al diode for different temperatures in the range 270 - 330 K with a charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

-16 -12 -8

32 36 40 44

III II I

1/kT (eV

^-1

) -l n( τT

2

)

Fig. 3-57. Arrhenius plots for Peak I to III obtained from the Q-DLTS spectra recorded in a ITO/PEDOT:PSS/PVK+PBD/Al diode for different temperatures in the range 270 - 330 K with a charging voltage: ΔV = + 6 V.

Table 3-7. Summary of the trap parameters in ITO/PEDOT/PVK+PBD/Al

Fig. 3-58. Q-DLTS spectra measured on a ITO/PEDOT:PSS/PVK+PBD+Pt complex/Al device using a charging voltage ΔV = + 6V for different charging time from 1 ms to 1 s at T=300 K.

0

Fig. 3-59. Resolved Q-DLTS spectra measured on a ITO/PEDOT:PSS/ PVK +PBD+Pt complex/Al device using a charging voltage ΔV = + 6V for charging time 1 s at T=300 K.

Fig. 3-60. Q-DLTS spectra measured on a ITO/PEDOT:PSS/PVK+PBD+Pt-complex/Al device in using a charging time τ_c = 1s and a charging voltage ΔV = + 6V for different temperatures in the range 270-330 K.

0 1000

0 1 2 3 4 5 6 7 8

Δ Q (pC )

log(τ) (τ: us)

270 K 330 K

Fig. 3-61. Peak I obtained from the Q-DLTS spectra recorded in a Pt-Fluorene complex diode for different temperatures in the range 270 - 330 K with a charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

0 250 500

0 1 2 3 4 5 6 7 8

Δ Q (p C )

log(τ) (τ: us)

270 K 330 K

Fig. 3-62. Peak III obtained from the Q-DLTS spectra recorded in a Pt-Fluorene complex diode for different temperatures in the range 270 - 330 K with a

charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

0 200 400

0 1 2 3 4 5 6 7 8

Δ Q (pC )

log(τ) (τ: us)

270 K 330 K

Fig. 3-63. Peak IV obtained from the Q-DLTS spectra recorded in a Pt-Fluorene complex diode for different temperatures in the range 270 - 330 K with a

charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

0 1000

0 1 2 3 4 5 6 7 8

Δ Q (pC )

log(τ) (τ: us)

270 K 330 K

Fig. 3-64. Peak V obtained from the Q-DLTS spectra recorded in a Pt-Fluorene complex diode for different temperatures in the range 270 - 330 K with a

charging time tc = 1 s, a charging voltage: ΔV = + 6 V.

-16 -12 -8 -4

32 36 40 44 48

I

V IV III

-l n (τ T

2

)

1/kT (eV

^-1

)

Fig. 3-65. Arrhenius plots for Peaks obtained from the Q-DLTS spectra recorded in a ITO/PEDOT:PSS/PVK+PBD+Pt complex/Al diode for different

temperatures in the range 270 - 330 K with a charging voltage: ΔV = + 6 V.

Table 3-8. Summary of the trap parameters in ITO/PEDOT/PVK+PBD+Pt complex/Al devices.

Device Parameter Peak I Peak III Peak IV Peak V Ea (eV) 0.32 0.51 0.25 0.18 σ (cm²) 2.6×10^-21 9.9×10^-20 6.0×10^-21 3.0×10^-21 PVK+PBD+

Pt complex N_T (cm^-3) 6.7×10¹⁶ 3.2×10¹⁶ 2.7×10¹⁶ 9.6×10¹⁶

在文檔中 有機發光二極體用高分子奈米複合材料之光電性質研究 (頁 91-103)