基于三萘苯的溶液可加工螺旋形寡聚物的合成及其在蓝光有机电致发光器件中的应用

近年来,人们在有机电致发光材料和器件结构方面取得了巨大的进步。然而由于蓝光材料具带隙宽的内禀属性,在发光效率、色纯度和稳定性上仍然面临巨大挑战。本文将螺旋形三萘苯共轭体系引入电致发光材料领域,它独特的螺旋形分子结构和易于化学修饰的特点有利于抑制聚集体和基激缔合物的形成。通过SiCl₄催化的环三缩合反应和Suzuki偶联反应,我们设计合成了以三萘基苯为核心,萘、蒽和三苯胺为取代基团的系列螺旋形蓝光寡聚物,并系统地研究了它们的热学、光物理和电化学性质。研究发现,萘和三苯胺取代的寡聚物1, 3, 5-三(3-(1-甲氧基萘-2-基)-4-甲氧基萘-1-基)苯(TNNB)和1, 3, 5-三(3-(4-(N, N-二苯胺基)苯基)-4-甲氧基萘-1-基)苯(TPANB)具有最好的热稳定性。在溶液中,这两种材料都具有深蓝发射,发射峰分别为382和415 nm;在薄膜中, TNNB的发射峰仅有1 nm的红移,而TPANB甚至产生了6 nm的蓝移。以这些寡聚物为发光材料,通过旋涂法制备的有机电致发光器件结果表明,基于TNNB的器件获得了最大亮度达到5273 cd·m^-2,色坐标(0.17, 0.11)的纯蓝光器件。

Synthesis of Solution-Processable Propeller-Shaped Oligomers Based on Trinaphthylbenzene and Their Application in Blue Organic Light-Emitting Diodes

Although considerable improvements have been achieved in novel materials and device architectures for organic light-emitting diodes (OLEDs), great challenges remain in efficiency, color purity, and stability for blue emitters because of their intrinsic wide band-gap. In this study, trinaphthylbenzene (TNB), a propeller-shaped conjugated system, is employed as the central moiety for the construction of the organic lightemitting materials. Its nonplanar propeller-shaped structure and easy chemical modification are beneficial for building three-dimensional (3D) π-π conjugated systems to suppress aggregates and excimers. We have demonstrated a facile approach for the synthesis of a set of propeller-shaped blue-emitting oligomers based on the TNB core with peripheral units of naphthalene, anthracene or triphenylamine via the combination of SiCl₄-catalyzed cyclotrimerization and Suzuki coupling reactions. The thermal, optical, and electrochemical properties of the materials were investigated. The results indicate that the naphthalene and triphenylamine substituted oligomers, 1, 3, 5-tris(3-(1-methoxynaphthalen-2-yl)-4-methoxynaphthalen-1-yl)benzene (TNNB) and 1, 3, 5-tris (3-(4-(N, N-diphenylamino)phenyl)-4-methoxynaphthalen-1-yl) benzene (TPANB), have the best thermal stability. They exhibit deep blue photoluminescence (PL) emission at 382 and 415 nm in solution, respectively. In comparison with the solution spectra, the emission spectra in films show only a very slight red-shift of 1 nm for TNNB and a blue-shift of 6 nm for TPANB. The electroluminescent device fabricated using TNNB as the emitter has a pure blue emission with a brightness of 5273 cd·m^-2 and Commission Internationale de L′Eclairage (CIE) coordinates of (0.17, 0.11).