Verykios Apostolis, Papadakis Michael, Soultati Anastasia, Skoulikidou Maria-Christina, Papaioannou George, Gardelis Spyros, Petsalakis Ioannis D, Theodorakopoulos Giannoula, Petropoulos Vasilis, Palilis Leonidas C, Fakis Mihalis, Vainos Nikolaos A, Alexandropoulos Dimitris, Davazoglou Dimitris, Pistolis George, Argitis Panagiotis, Coutsolelos Athanassios G, Vasilopoulou Maria
Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi, 15310 Athens, Greece.
Department of Physics and Department of Materials Science, University of Patras, 26504 Patras, Greece.
ACS Omega. 2018 Aug 28;3(8):10008-10018. doi: 10.1021/acsomega.8b01503. eCollection 2018 Aug 31.
Here, we use a simple and effective method to accomplish energy level alignment and thus electron injection barrier control in organic light emitting diodes (OLEDs) with a conventional architecture based on a green emissive copolymer. In particular, a series of functionalized zinc porphyrin compounds bearing π-delocalized triazine electron withdrawing spacers for efficient intramolecular electron transfer and different terminal groups such as glycine moieties in their peripheral substitutes are employed as thin interlayers at the emissive layer/Al (cathode) interface to realize efficient electron injection/transport. The effects of spatial (i.e., assembly) configuration, molecular dipole moment and type of peripheral group termination on the optical properties and energy level tuning are investigated by steady-state and time-resolved photoluminescence spectroscopy in F8BT/porphyrin films, by photovoltage measurements in OLED devices and by surface work function measurements in Al electrodes modified with the functionalized zinc porphyrins. The performance of OLEDs is significantly improved upon using the functionalized porphyrin interlayers with the recorded luminance of the devices to reach values 1 order of magnitude higher than that of the reference diode without any electron injection/transport interlayer.
在此，我们采用一种简单有效的方法，在基于绿色发光共聚物的传统结构有机发光二极管（OLED）中实现能级对齐，进而控制电子注入势垒。具体而言，一系列带有π-离域三嗪吸电子间隔基以实现高效分子内电子转移且在其外围取代基中有不同端基（如甘氨酸部分）的功能化锌卟啉化合物，被用作发光层/Al（阴极）界面处的薄夹层，以实现高效的电子注入/传输。通过对F8BT/卟啉薄膜进行稳态和时间分辨光致发光光谱研究、对OLED器件进行光电压测量以及对用功能化锌卟啉修饰的Al电极进行表面功函数测量，研究了空间（即组装）构型、分子偶极矩和外围基团端基类型对光学性质和能级调谐的影响。使用功能化卟啉夹层后，OLED的性能得到显著改善，器件记录的亮度比没有任何电子注入/传输夹层的参考二极管高出1个数量级。
