Sharma Nidhi, Spuling Eduard, Mattern Cornelia M, Li Wenbo, Fuhr Olaf, Tsuchiya Youichi, Adachi Chihaya, Bräse Stefan, Samuel Ifor D W, Zysman-Colman Eli
Organic Semiconductor Centre , EaStCHEM School of Chemistry , University of St Andrews , St Andrews, Fife, KY16 9ST , UK . Email:
Organic Semiconductor Centre , SUPA , School of Physics and Astronomy , University of St Andrews , North Haugh, St Andrews , KY16 9SS , UK . Email:
Chem Sci. 2019 May 29;10(27):6689-6696. doi: 10.1039/c9sc01821b. eCollection 2019 Jul 21.
The carbazolophane (Czp) donor unit (indolo[2.2]paracyclophane) is introduced to the design pool of donors in thermally activated delayed fluorescence emitters. The increased steric bulk of the annelated donor unit forces an increased torsion between the carbazole and the aryl bridge resulting in a decreased Δ and an enhancement of the thermally activated delayed fluorescence in the triazine-containing emitter . Further, the closely stacked carbazole and benzene units of the paracyclophane show through-space π-π interactions, effectively increasing the spatial occupation for the HOMO orbital. The chiroptical properties of enantiomers of [2.2]paracyclophane reveal mirror image circular dichroism (CD) and circularly polarized luminescence (CPL) with of 1.3 × 10. is a sky-blue emitter with of 480 nm, a very small Δ of 0.16 eV and high of 70% in 10 wt% doped films. Sky blue-emitting OLEDs were fabricated with this new TADF emitter showing a high maximum EQE of 17% with CIE coordinates of (0.17, 0.25). A moderate EQE roll-off was also observed with an EQE of 12% at a display relevant luminance of 100 cd m. Our results show that the Czp donor contributes to both a decreased Δ and an increased photoluminescence quantum yield, both advantageous in the molecular design of TADF emitters.
将咔唑并环戊烷（Czp）供体单元（吲哚并[2.2]对环芳烷）引入热激活延迟荧光发光体的供体设计库中。稠合供体单元空间位阻的增加迫使咔唑与芳基桥之间的扭转增加，导致含三嗪发光体中的Δ减小，热激活延迟荧光增强。此外，对环芳烷紧密堆积的咔唑和苯单元表现出空间π-π相互作用，有效地增加了HOMO轨道的空间占有率。[2.2]对环芳烷对映体的手性光学性质显示出镜像圆二色性（CD）和圆偏振发光（CPL），其值为1.3×10。是一种天蓝色发光体，在10 wt%掺杂薄膜中的发射波长为480 nm，Δ非常小，为0.16 eV，量子产率高达70%。用这种新型热激活延迟荧光发光体制备了天蓝色发光有机发光二极管，其最大外量子效率高达17%，CIE坐标为（0.17, 0.25）。在100 cd m的显示相关亮度下，外量子效率为12%时也观察到了适度的外量子效率下降。我们的结果表明，Czp供体有助于降低Δ并提高光致发光量子产率，这两者在热激活延迟荧光发光体的分子设计中都是有利的。
