Abstract：
Understanding the hole-injection mechanism and improving the hole-injection property are of pivotal importance in the future development of organic optoelectronic devices. Electron-acceptor molecules with high electron affinity (EA) are widely used in electronic applications, such as hole injection and p-doping. Although p-doping has generally been studied in terms of matching the ionization energy (IE) of organic semiconductors with the EA of acceptor molecules, little is known about the effect of the EA of acceptor molecules on the hole-injection property. In this work, the hole-injection mechanism in devices is completely clarified, and a strategy to optimize the hole-injection property of the acceptor molecule is developed. Efficient and stable hole injection is found to be possible even into materials with IEs as high as 5.8 eV by controlling the charged state of an acceptor molecule with an EA of about 5.0 eV. This excellent hole-injection property enables direct hole injection into an emitting layer, realizing a pure blue organic light-emitting diode with an extraordinarily low turn-on voltage of 2.67 V, a power efficiency of 29 lm W-1 , an external quantum efficiency of 28% and a Commission Internationale de l\'Eclairage y coordinate of less than 0.10.
摘要：
了解空穴注入机理和改善空穴注入性能对于有机光电器件的未来发展至关重要。具有高电子亲和力（EA）的电子受体分子广泛用于电子应用。例如空穴注入和p掺杂。尽管通常已经在将有机半导体的电离能（IE）与受体分子的EA相匹配方面研究了p掺杂，受体分子的EA对空穴注入性能的影响知之甚少。在这项工作中,完全阐明了器件中的空穴注入机理，并开发了一种优化受体分子空穴注入特性的策略。通过控制具有约5.0eV的EA的受体分子的带电状态,发现甚至在IE高达5.8eV的材料中,有效且稳定的空穴注入也是可能的。这种优异的空穴注入性能使得能够将空穴直接注入到发光层中。实现具有2.67V的极低接通电压的纯蓝色有机发光二极管，29lmW-1的电源效率，外部量子效率为28%，国际委员会定义的y坐标小于0.10。
