Kok Cansu, Doyranli Ceylan, Canımkurbey Betül, Pıravadılı Mucur Selin, Koyuncu Sermet
Department of Energy Resources and Management, Çanakkale Onsekiz Mart University 17020 Çanakkale Turkey.
Department of Chemistry, Faculty of Arts and Sciences, Yıldız Technical University 34220 Istanbul Turkey.
RSC Adv. 2020 May 15;10(32):18639-18647. doi: 10.1039/d0ra02527e. eCollection 2020 May 14.
With the purpose of obtaining white emission from single layer organic light emitting diodes (OLEDs), fluorene benzotriazole based polymers with double bond subunits (namely TP2 and SP3 with and without thiophene linker, respectively) were synthesized by a Suzuki cross-coupling polymerization reaction. SP3 and TP2 were used as an emissive layer of the OLED devices due to their outstanding solubility in organic solvents, photoluminescence intensity and morphological suitability for fine thin film-forming capability. The optical, electrochemical, light emission and electroluminescence characteristics, Density Functional Theory (DFT) calculations and admittance spectroscopic analysis of OLEDs based on SP3 and TP2 were realized in detail to understand the effects of thiophene linker addition as a donor unit to the main chain of fluorene benzotriazole based polymers. As a result, TP2 emitted a bright yellow emission with a maximum brightness of 243 cd m at 40 mA cm, and a maximum current efficiency of 1.38 cd A with more broad electroluminescence characteristics than SP3 polymer without the thiophene linker. SP3 emitted a greenish yellow emission with a maximum brightness of 1001 cd m at 845 mA cm, and a maximum current efficiency of 0.33 cd A. Carrier transport properties, charge carrier transit time and the equivalent circuit modelling studies were obtained through admittance spectroscopy. An equivalent circuit model with a combination of two resistors and one capacitor explained the charge conduction mechanism of SP3 and TP2 based OLEDs. SP3 and TP2 OLED devices represented typical p-type transporting characteristics with mobilities of 0.073 and 0.017 cm V s, respectively with simplified device configuration. All the results indicate that thiophene addition to the main chain of fluorene benzotriazole based polymers with double bond subunits lead to a promising candidate for white emissive materials used in single layer white OLEDs.
为了从单层有机发光二极管（OLED）中获得白色发射光，通过铃木交叉偶联聚合反应合成了具有双键亚基的芴苯并三唑基聚合物（分别为带有和不带有噻吩连接基的TP2和SP3）。由于SP3和TP2在有机溶剂中具有出色的溶解性、光致发光强度以及形成精细薄膜的形态适宜性，它们被用作OLED器件的发光层。详细研究了基于SP3和TP2的OLED的光学、电化学、发光和电致发光特性、密度泛函理论（DFT）计算以及导纳光谱分析，以了解作为供体单元的噻吩连接基添加到芴苯并三唑基聚合物主链上的影响。结果表明，TP2发出亮黄色发射光，在40 mA/cm²时最大亮度为243 cd/m²，最大电流效率为1.38 cd/A，与没有噻吩连接基的SP3聚合物相比，具有更宽的电致发光特性。SP3发出黄绿色发射光，在845 mA/cm²时最大亮度为1001 cd/m²，最大电流效率为0.33 cd/A。通过导纳光谱获得了载流子传输特性、电荷载流子渡越时间和等效电路建模研究。由两个电阻和一个电容组成的等效电路模型解释了基于SP3和TP2的OLED的电荷传导机制。在简化的器件结构下，SP3和TP2 OLED器件分别表现出典型的p型传输特性，迁移率分别为0.073和0.017 cm²/V·s。所有结果表明，在带有双键亚基的芴苯并三唑基聚合物主链中添加噻吩会产生一种有前景的单层白色OLED白色发光材料候选物。
