Organic light-emitting diodes (OLEDs) nowadays represent one of the most promising and dominant technology in the market of displays and illumination equipment. OLEDs are superior to competitive technologies with respect of mechanical flexibility, low response time, quality of image, transparency, low mass and wide range of working temperatures [1,2]. In this work blue phosphorescent organic light-emitting diodes (PhOLEDs) with maximum external quantum efficiency from 22.7 to 30.5% were fabricated using new bipolar derivatives of benzimidazole linked through phenyl spacer with the different number of tert-butyl substituted carbazoles, as hosts. Applicability of the newly synthesized compounds as hosts for blue PhOLEDs was justified by their high triplet levels (2.94-2.98 eV), bipolar transporting properties with charge mobilities up to 2.34×10-3 cm2/V·s at electric field of 2.7×105 V/cm, and high ionization potentials (5.63-5.81 eV).
NEW BIPOLAR HOSTS FOR HIGH EFFICIENCY OLEDS
Simas Macionis1, Dalius Gudeika1, Dmytro Volyniuk1, Oleksandr Bezvikonnyi1, Jiun Haw Lee2, Pei-Hsi Lee2, Chia-Hsun Chen2, Tien-Lung Chiu3, Juozas V. Grazulevicius1
1 Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254, Kaunas, Lithuania
2 Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
3 Department of Electrical Engineering, Yuan Ze University, 135 Yuan-Tung Road, Taoyuan 32003, Taiwan
[1] N. Savage, Tomorrow's industries: from OLEDs to nanomaterials, Nature 576, (7786):S20-S22, (2019).
[2] K. Leo, Efficient and flexible solution, Nat. Photon, 5, 716 (2011).