Silicon Based Inorganic/Organic Hybrid Materials for Deep Blue PHOLEDs

Abstract

AbstractDeep blue PHOLED was achieved in the simple device structure of ITO/SiTPA/SiCBP: FIr6 5 wt%/SiTAZ/Liq/Al, where active layers were silicon based inorganic/organic hybrid materials of the types, SiTPA, SiCBP, and SiTAZ for HTL, EML host, and ETL respectively. Silicon incorporation into organic framework not only provided necessary morphological stability, but also engaged enhanced charge transporting capability essential to achieve highly efficient deep blue PHOLEDs. As a result, high performance silicon based HTL, EML host, and ETL materials were developed, exhibiting high charge mobility in the range of 10−4 ∼ 10−3 cm2V−1s−1 and high triplet energy of 2.88 eV, 3.05 eV and 2.84 eV, respectively.Even with the simple four layer device structure of PHOLEDs comprising silicon based active layers, maximum external quantum efficiency (EQE) of 17 % and CIE coordinates of (0.15, 0.22) were achieved. Moreover, an EQE of 15% was recorded at a luminance of 1000 cd m−1, which was the result of reduced efficiency roll-off due to the efficient confinement of FIr6 triplet energy by surrounding silicon based inorganic/organic hybrid materials developed in this work. Structures of inorganic/organic hybrid materials and their photo-physical properties as well as device physics for high performance deep blue PHOLEDs will be presented.