我們利用高分子液晶材料來製備成偏極化電激發光元件，元件結 構為ITO / rubbed-PEDOT / polymer / Ca / Al。所得的偏極化元件性質 列於 Table 8，以 P1 的元件性質為例，EL=456 nm (Fig. 12)，驅動電
壓為 7V，極化值約 6.4，最大亮度為 430 cd/m2 (Fig. 13)。
之後用摻混的方法來提升元件性質，將藍光材料P3 摻混 5%的綠
光材料P4 及 5%紅光材料 P5，其中 P3 當作主體(Host)，P4、P5 當作 客體(Guest)，利用其分子鏈間的能量轉移(intrachain energy transfer)，
來提升元件性質，摻混後的元件性質列於 Table 8。在摻混後，綠光
材料P4 偏極化亮度由原來的 1039 cd/m2提升至 2205 cd/m2，提高至2 倍，效率提升至 0.60 cd/A; 紅光材料 P5 偏極化亮度由原來的 284 cd/m2提升至1146 cd/m2，提高至4 倍，效率提升至 0.22 cd/A，摻混 的方法確實達到提升元件性質的效果。
最後利用藍光 P3 做為主體，摻混綠光 P4、紅光 P5 材料，來製 備偏極化白光元件，總共有三種不同的比例，分別製作出白光元件 A、B、C，Fig. 14 為偏極化白光元件 A 的 EL 光譜，最大亮度可達 581 cd/m2 (Fig. 15)，由圖中可看出藍光、綠光、紅光三元色的波峰，
且波長涵蓋 400 nm 至 700 nm 之間，確實有構成白光的要件，並且有 極化的效果。所有的偏極化白光元件性質皆列於 Table 9，其中元件 C 性質最佳，偏極化白光亮度可達1895 cd/m2、效率為0.24 cd/A、極化 值為 4.4。白光元件 A 的 CIE 1931(x,y)座標為(0.332,0.363)，非常接 近純白光(0.333,0.333)。
N SN C8H17
H17C8
8 5 1 5
N
C5H11
8 0 2 0
C8H17 H17C8
N SN
S S
C8H17
H17C8 N
S N
8 5 1 0 5
P1
P2
P3
Scheme 5
Table 6. Polymerization results and phase transition temperatures of polymers.
a) The temperatures were observed by DSC.
b) The temperatures were observed by TGA.
c) The temperatures were observed by POM; G: glassy state, N: nematic phase, I:
isotropic.
Polymers Yield (%) Mn Mw Mw / Mn Tg (℃)a) Td (℃)b) Phase transition temperatures (℃)c) P3 68.8 12200 18200 1.49 71.7 373 G 101 N >300 I
P4 63.5 10700 15600 1.45 106.3 410 G 125 N >300 I
P5 61.2 10300 16200 1.57 107.6 415 G 127 N >300 I
Table 7. Polarized UV-vis absorption, polarized PL emission and polarized ratio of polymers.
Polarized ratio Polymer Polarized UVmax
Absorption (nm)
Polarized PLmax Emission (nm)
UV-vis (UV///UV┴)
PL (PL///PL┴)
P3 378 449 6.6 5.9
P4 376(434) 553 6.3 5.7
P5 377(435,520) 651 6.5 5.7
Table 8. Polarized device properties.
Polymer ELmax (nm)
V turn on
(V)
Luminance (Max) (cd/m2)
Efficiency (Max) (cd/A)
Polarized ratio (EL///EL┴)
CIE 1931 (x,y)
P3 456 7 430 0.08 6.4 (0.186,0.208)
P4 540 6 1039 0.40 6.3 (0.382,0.573)
P5 652 7 284 0.05 5.4 (0.672,0.322)
P3+P4 (5%) 538 7 2205 0.60 5.5 (0.352,0.559)
P3+P5 (5%) 644 7 1146 0.22 5.2 (0.620,0.323)
Table 9. Properties of polarized white emission devices.
Device P3 : P4 : P5 (mg)
ELmax (nm)
Vturn on
(V)
Luminance (Max) (cd/m2)
Polarized ratio
(EL///EL┴) CIE 1931(x,y) A 100:0.08:0.10 528 6 581 4.0 (0.332,0.363)
B 100:0.06:0.12 525 6 1358 4.6 (0.343,0.361)
C 100:0.04:0.12 534 6 1895 4.4 (0.322,0.368)
300 350 400 450 500 550 600 0.0
0.2 0.4 0.6 0.8 1.0 1.2
Intensity (arb. units)
Wavelength (nm)
P1-UV∥
P1-UV⊥
P1-PL∥
P1-PL⊥
Fig. 10. DSC thermogram of polymer P3.
Fig. 11. Polarized UV-vis absorption and polarized PL emission spectra of P3.
Fig. 12. Polarized EL spectra of P3 in ITO/aligned PEDOT/P1/Ca/Al device.
Fig. 13. J-V (□) and L-V (•) curves of P1 in ITO/aligned PEDOT /P3/Ca/Al device.
400 450 500 550 600 650 700
0.0
Intensity (arb. units)
Wavelength (nm) Current density (mA/cm2 )
0
Fig. 14. Polarized EL spectra of device A in ITO/aligned PEDOT/
polymer P1+P2+P3/Ca/Al device.
Fig. 15. J-V (□) and L-V (•) curves of device A in ITO/aligned PEDOT /polymer P1+P2 +P3/Ca/Al device.
350 400 450 500 550 600 650 700 750
0.0
Intensity (arb. units)
Wavelength (nm) Current density (mA/cm2 )
0
五、結論：
於三年計畫過程中，本實驗室合成出各種不同系列的小分子、高 分子液晶材料，皆可製作成偏極化電激發光元件，其熱性質或光電性 質結果亦已逐年發表於國際期刊中。本實驗室也成功地製備出偏極化 的藍光、綠光、紅光電激發光元件，並且用摻混的方法來製備出偏極 化白光元件，最大偏極化白光亮度可達1895 cd/m2、效率為0.24 cd/A、極化值為 4.4，另外白光元件 A 的 CIE 1931(x,y)座標為(0.332, 0.363)，非常接近純白光(0.333,0.333)，非常有潛力應用在液晶顯示器 的背光板上。
六、已發表論文
1. S. W. Chang, A. H. Li, C. W. Liao and C. S. Hsu, Jpn. J. Appl. Phys. 41, 2002, 1374.
2. S. W. Chang and C. S. Hsu, J. Polym. Res. 9, 2002, 1.
3. Y. H. Yao, L. R. Kung and C. S. Hsu accepted in Jpn. J. Appl. Phys.
4. Y. H. Yao, L. R. Kung and C. S. Hsu submitted in Journal of Polymer Science Part A: Polymer Chemistry.
5. Y. H. Yao, L. R. Kung and C. S. Hsu submitted in Liquid Crystal.
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