Novel White Electroluminescent Single Polymer Derived from Fluorene and Quinacridone
详细信息 查看全文
- 作者：Jun Liu ; Baoxiang Gao ; Yanxiang Cheng ; Zhiyuan Xie ; Yanhou Geng ; Lixiang Wang ; Xiabin Jing ; Fosong Wang
- 刊名：Macromolecules
- 出版年：2008
- 出版时间：February 26, 2008
- 年：2008
- 卷：41
- 期：4
- 页码：1162 - 1167
- 全文大小：119K
- 年卷期：v.41,no.4(February 26, 2008)
- ISSN：1520-5835
文摘
A novel series of white light emitting single polymers are prepared by incorporating low contentsof quinacridone into the main chain of polyfluorene. This is the first report of quinacridone-containing conjugatedpolymer. Single layer devices (ITO/PEDOT:PSS/polymer/Ca/Al) are fabricated with these polymers. Energy transferfrom fluorene segments to quinacridone unit is observed. Moreover, in the EL process, quinacridone unit cantrap electrons and cannot trap holes from fluorene segments. Electroluminescence (EL) spectra of these polymersexhibit simultaneous blue emission (
max = 425 nm/445 nm) from the fluorene segments and yellow emission(max = 540 nm/580 nm) from the quinacridone unit. The latter one comes from the partial energy transfer andcharge trapping from the fluorene segments to the quinacridone unit. With the increase of the quinacridone unit'scontent in the copolymers, the relative intensity of the orange emission band in the EL spectra becomes strongerowing to the more complete energy transfer and charge trapping. For the polymer (PFQA3) with the quinacridoneunit's content of 0.03 mol %, its EL spectrum shows balanced intensities of blue emission and orange emission,leading to white emission with CIE coordinates of (0.27, 0.35). Single layer device of this polymer exhibits theturn-on voltage of 3.5 V, luminous efficiency of 3.47 cd/A, power efficiency of 2.18 lm/W, external quantumefficiency of 1.33% and maximum brightness of 9062 cd/m2. Increase of the quinacridone unit's content resultsin increased turn-on voltages and decreased EL efficiencies of the resulting devices owing to the serious trap ofelectrons by quinacridone unit and exciton quenching of quinacridone unit at high concentration, respectively.
max = 425 nm/445 nm) from the fluorene segments and yellow emission(max = 540 nm/580 nm) from the quinacridone unit. The latter one comes from the partial energy transfer andcharge trapping from the fluorene segments to the quinacridone unit. With the increase of the quinacridone unit'scontent in the copolymers, the relative intensity of the orange emission band in the EL spectra becomes strongerowing to the more complete energy transfer and charge trapping. For the polymer (PFQA3) with the quinacridoneunit's content of 0.03 mol %, its EL spectrum shows balanced intensities of blue emission and orange emission,leading to white emission with CIE coordinates of (0.27, 0.35). Single layer device of this polymer exhibits theturn-on voltage of 3.5 V, luminous efficiency of 3.47 cd/A, power efficiency of 2.18 lm/W, external quantumefficiency of 1.33% and maximum brightness of 9062 cd/m2. Increase of the quinacridone unit's content resultsin increased turn-on voltages and decreased EL efficiencies of the resulting devices owing to the serious trap ofelectrons by quinacridone unit and exciton quenching of quinacridone unit at high concentration, respectively.