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Noncrystallizable Charge‐Transporting Hosts for Phosphorescent Organic Light Emitting Diodes: Decreased Emitter Aggregation
Author(s) -
Chakraborty Rajarshi,
Molaire Michel F.,
Weiss David S.,
Pecorella Joseph N.,
Clark Daniel A.,
Rothberg Lewis J.,
Zeng Honzhi,
Yu Tianhao
Publication year - 2020
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201900713
Subject(s) - phosphorescence , common emitter , oled , quenching (fluorescence) , materials science , photoluminescence , exciton , photochemistry , optoelectronics , quantum efficiency , analytical chemistry (journal) , fluorescence , chemistry , layer (electronics) , nanotechnology , optics , physics , organic chemistry , quantum mechanics
Organic light emitting diodes (OLEDs) with phosphorescent emitters (PhOLEDs) exhibit efficiency roll‐off at high luminance because the long‐lived triplet excitons are prone to emission quenching and triplet–triplet annihilation (TTA). Herein, the synthesis, purification, and characterization of an emitter layer host that is a noncrystallizable mixture of isomers (OLEDIQ HT‐1700) is described. In this host, the triplet lifetime of a phosphorescent yellow emitter (IYD‐560) is increased relative to a conventional single‐molecule host (3,3′‐di(9H‐carbazol‐9‐yl)‐1,1′‐biphenyl, mCBP), with high photoluminescence quantum yields and unchanged emission spectra. Characterization of the doped films with differential scanning calorimetry (DSC) and microscopy showed that the emitter is incompatible in mCBP but totally compatible with the noncrystalline host. The increased triplet lifetime is interpreted as decreased triplet quenching in the noncrystallizable host‐based film, while emitter aggregation in the conventional host film leads to triplet quenching.