Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

被引：91

作者：

Etherington, Marc K. ^{[1
]}

Kukhta, Nadzeya A. ^{[2
]}

Higginbotham, Heather F. ^{[1
]}

Danos, Andrew ^{[1
]}

Bismillah, Aisha N. ^{[2
]}

Graves, David R. ^{[1
]}

McGonigal, Paul R. ^{[2
]}

Haase, Nils ^{[3
,4
]}

Morherr, Antonia ^{[3
]}

Batsanov, Andrei S. ^{[2
]}

Pflumm, Christof ^{[3
]}

Bhalla, Vandana ^{[2
,5
]}

Bryce, Martin R. ^{[2
]}

Monkman, Andrew P. ^{[1
]}

机构：

[1] Univ Durham, Dept Phys, South Rd, Durham DH1 3LE, England

[2] Univ Durham, Dept Chem, South Rd, Durham DH1 3LE, England

[3] Merck KGaA, Performance Mat Display Solut, Frankfurter Str 250, D-64293 Darmstadt, Germany

[4] Univ Augsburg, Inst Phys Expt Phys 4, Univ Str 1, D-86135 Augsburg, Germany

[5] Guru Nanak Dev Univ, Dept Chem, Grand Trunk Rd,Off NH 1, Amritsar 143005, Punjab, India

来源：

JOURNAL OF PHYSICAL CHEMISTRY C | 2019年 / 123卷 / 17期

基金：

英国工程与自然科学研究理事会;

关键词：

LIGHT-EMITTING-DIODES; AGGREGATION-INDUCED EMISSION; HOST; EFFICIENCY; TADF; PHOSPHORESCENT; DEVICES; STATES; OLEDS;

D O I：

10.1021/acs.jpcc.9b01458

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

We expose significant changes in the emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise from the presence of persistent dimer states in thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electroluminescence. The dimer species is sensitive to the sample preparation method, and its enduring presence contributes to the widely reported concentration-mediated red shift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The dimerization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consideration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.

引用

页码：11109 / 11117

页数：9

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