二苯基氧磷修饰的不对称三嗪主体材料的理论研究

Theoretical Study of Asymmetric Triazine Host Materials with Diphenylphosphine Oxide Substituents

近年来,电致磷光器件因其在全色显示和固体照明领域的潜在应用而备受关注。文中针对电致磷光器件中的主体材料,设计了基于二苯氧磷的一系列三嗪衍生物,并通过密度泛函理论(DFT)对三嗪衍生物进行了系统的量子化学理论研究。研究发现:三嗪核决定了该类材料具有较高的三线态能级(2.84 eV^3.02 eV),而其前沿轨道能级可通过二苯氧磷和咔唑修饰单元数量及其比例来逐级调控,最高占据轨道(HOMO)由咔唑决定,维持在-5.85 eV;而最低未占据轨道(LUMO)受二苯氧磷影响,可以从-1.42 eV降低到-2.33 eV,从而具有独立可调的LUMO能级。综合比较发现,具有两个咔唑和一个二苯氧磷的不对称三嗪(DCzPT)比较适合作为蓝光客体的主体材料,这是因为DCzPT不仅具有高的三线态能级(3.02 eV)和低的LUMO值(-1.74 eV),而且具有较高的电子和空穴的传输能力。

Recently, phosphorescent organic light-emitting diodes （PhOLEDs） have recieved considerable attention for their potential applications in full-color displays and large-area solid-state lighting. In this contribution, a series of triazine host materials with diphenylphosphine oxide substituents for PhOLEDs are designed and investigated by density functional theory （DFT）. The triplet energy levels determined by the triazine core remain high （2.84 -3.02 eV） at various substitution patterns of diphenylphosphine oxide and carbazole. Interestingly, the highest occupied molecular orbital （HOMO） dominated by the earbazole maintains around -5.85 eV, while the lowest unoccupied molecular orbital （LUMO） is inde- pendently tuned from - 1.42eV to -2.33 eV according to the number of diphenylphosphine oxide sub- stituent. For the high triplet energy level （3.02 eV）, lower LUMO （ - 1.74 eV ） and higher charge transfer, the two carbazole and one diphenylphosphine oxide substituted asymmetric triazine of DCzPT is suggested to be the best host materials for blue PhOLEDs.