Excimer Formation by Steric Twisting in Carbazole and Triphenylamine-Based Host Materials
Excimer Formation by Steric Twisting in Carbazole and Triphenylamine-Based Host Materials
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DOI：
10.1021/jp512772j
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发表时间：
2015-02-05
影响因子：
3.7
通讯作者：
Koehler, Anna
中科院分区：
文献类型：
--
作者：
Bagnich, Sergey A.;Athanasopoulos, Stavros;Koehler, Anna
本文详细研究了4，4 ′-双（N-咔唑基）-1，1 ′-联苯（CBP）和N，N，N ′，N ′-四苯基联苯胺（CBP）在溶液和纯膜中的发光性质。将这些化合物与其在联苯核的2和2'位含有甲基的衍生物CDBP和TDAD进行比较。我们发现，而在CDBP和TDAD的空间扭曲导致约3.0和3.1 eV的高三重态能量，分别，这些化合物也倾向于形成三重态准分子在一个整洁的膜，在CBP和ESTA相反。通过比较与N-苯基咔唑（NPC）和三苯胺（TPA），这些化合物的基础上，以及与刚性螺类似物CBP和ESTA，我们表明，减少激基缔合物形成CBP和ESTA可以归因于本地化的激发到中央联苯部分的分子。
This paper presents a detailed spectroscopic investigation of luminescence properties of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) and N,N,N',N'-tetraphenylbenzidine (TAD) in solutions and neat films. These compounds are compared to their derivatives CDBP and TDAD that contain methyl groups in the 2 and 2' position of the biphenyl core. We find that whereas steric twisting in CDBP and TDAD leads to a high triplet energy of about 3.0 and 3.1 eV, respectively, these compounds also tend to form triplet excimers in a neat film, in contrast to CBP and TAD. By comparison with N-phenylcarbazole (NPC) and triphenylamine (TPA), on which these compounds are based, as well as with the rigid spiro analogues to CBP and TAD we show that the reduced excimer formation in CBP and TAD can be attributed to a localization of the excitation onto the central biphenyl part of the molecule.