Poly (carbazolylene phenylene cyanovinylene) 材料製備與發光特性研究

Abstract

本研究利用Knoevenagel reaction 將1,4-及1,3-phenylene diacetonitrile 與N-(2-octyl)-3,6-diformylcarbazole反應合成出不同π-有效共軛鏈長度（π-effective conjugation lengths） 的Poly[ （p or m）(carbazolylene phenylene cyanovinylene) ]【p-PCPC及m-PCPC】配位的共軛高分子。利用引入不同配位（para及meta）來達到控制高分子鏈段的共軛長度。所製得p-PCPC及m-PCPC高分子具有不錯的熱穩定性（在氮氣下5﹪熱損失重量分別為453℃及475℃），可發現meta 配位相較para配位構形高分子較具有好的熱穩定性。從Uv-visible 吸收光譜可發現在393nm至413nm左右顯示出一個相當強的π-π*吸收峰，另外p-PCPC及m-PCPC PL光譜中最大發光波長分別從514nm至578nm，這種紅移現象和其配位有關。從CV （cyclic voltammetry）的電化學實驗分析可知其highest occupied molecular orbitals （HOMO）為5.30 eV及5.60 eV，而lowest unoccupied molecular orbitals （LUMO）為3.21 eV及3.30 eV 。另一方面所製備的發光二極體發光元件〔ITO/polymer/Al〕起始電壓約為3-4V，並且p-PCPC及m-PCPC分別發出黃-紅光（601nm）及綠光（534nm）。

Poly[ [p,or（m）-carbazolylene-phenylene-cyanovinylene) ]【p-PCPC, m-PCPC】polymers with varyingπ-effective conjugation lengths was synthesized using Knoevenagel reaction between 1,4-（1,3）-phenylene diacetonitrile and N-(2-octanyl)-3,6-diformylcarbazole. The conjugation lengths of polymers were controlled by kink （para and meta）linkages. The resulting polymers（p-PCPC）and m-PCPC have good thermally stable on heating（the weight loss was less than 5﹪on heating to about 435℃ and 475℃ under nitrogen atmosphere）, meat conformations are more stable than para conformations. The Uv-visible absorbance of present polymers showed strong absorption bands around 393-413 nm byπ-π* transition. In addition, the maximum photoluminescence （PL）of p-PCPC and m-PCPC were changed from 514 nm to 578 nm . The PL of p-PCPC was red-shifted about 60 nm compared to that m-PCPC depending on link structure. Electrochemical analyses by cyclic voltagemetry indicate that highest occupied molecular orbitals （HOMO） of p-PCPC and m-PCPC to be（5.30 eV , 5.60 eV, and lowest unoccupied molecular orbitals （LUMO）energy levels（3.21 eV, 3.30 eV. Otherwise , a single layer light emitting diode device was fabricate, which has simple ITO / Polymer / Al configuration. The threshold voltage of polymers was in range of 3-4 V. These polymers of p-PCPC and m-PCPC exhibit red-yellow and green light-emitting diodes in EL emissive band at 601nm and 534 nm .