Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes
Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes
复制标题
DOI：
10.1021/acsami.7b05615
复制
发表时间：
2017-07-19
影响因子：
9.5
通讯作者：
Lee, Min Hyung
中科院分区：
文献类型：
--
作者：
Lee, Young Hoon;Park, Sunghee;Lee, Min Hyung
提出了一种高效热激活延迟荧光（TADF）的合成方法，该方法使用邻位供体(D)受体(A)化合物（PXZoB， DPAoB和CzoB），其中受体是基于三芳基硼，供体是苯恶嗪（PXZ），二苯胺（DPA）或咔唑（Cz）。结合正交D-A连通性，三芳基硼的体积特性赋予D-A二极体以高度扭曲的d-排列固有的空间“锁定”，导致单重态和三重态激发态（Delta E-sT）之间的能量差很小，从而表现出非常有效的TADF，其寿命在微秒范围内。与之形成鲜明对比的是，对应的对D-A衍生物DPApB和CzpB仅显示短暂的正常荧光。有机发光二极管（oled）结合所提出的邻位D-A化合物作为发射体，显示橙色，绿蓝色和纯蓝色发射，并表现出高的外部量子效率（eta(EQE)）。特别是，基于邻位D-A发射体和咔唑给体（CzoB）的纯蓝色oled显示出创纪录的22.6%的eta(EQE)， CIE颜色坐标为（0.139,0.150），很好地说明了所提出的d-方法的有效性。经光学优化后，eta（EQE）进一步提高到24.1%。
A synthetic approach to highly efficient thermally activated delayed fluorescence (TADF) is proposed that uses ortho donor (D) acceptor (A) compounds (PXZoB, DPAoB, and CzoB), wherein the acceptor is based on triarylboron and the donor is phenoxazine (PXZ), diphenylamine (DPA), or carbazole (Cz). Combined with the ortho D-A connectivity, the bulky nature of the triarylboron endows the D-A dyads with inherent steric "locking" for a highly twisteD-Arrangement, leading to a small energy difference between singlet and triplet excited states (Delta E-sT) and thus exhibiting very efficient TADF with microsecond-range lifetimes. In sharp contrast, the Corresponding para D-A derivatives, DPApB and CzpB, only display short-lived, normal fluorescence. Organic light-emitting diodes (OLEDs) incorporating the proposed ortho D-A compounds as emitters display orange, greenish-blue, and pure blue emission and exhibit high external quantum efficiency (eta(EQE)). In particular, the pure blue OLEDs based on the proposed ortho D-A emitters with a carbazole donor (CzoB) show a record-high eta(EQE) of 22.6% with CIE color coordinates of (0.139, 0.150), well illustrating the validity of the proposeD-Approach. Upon optical optimization, the eta(EQE) is further improved to 24.1%.