《Asymmetrically difunctionalized dibenzo[b,d]furan-based hole blocking materials for high-performance blue phosphorescent organic light-emitting diodes》 was published in Dyes and Pigments in 2020. These research results belong to Hong, Soojin; Chung, Won Jae; Jang, Seokhoon; Yu, Gyeonghwa; Lee, Jun Yeob; Lee, Youngu. Category: pyridine-derivatives The article mentions the following:
Three new hole blocking materials based on asym. difunctionalized dibenzo[b,d]furan, diphenyl(2-(pyridin-3-yl)dibenzo[b,d]furan-6-yl)phosphine oxide (DBFPO-Py), diphenyl(2-(pyrimidin-5-yl)dibenzo[b,d]furan-6-yl)phosphine oxide (DBFPO-Pyr), and diphenyl(2-(4-(triphenylsilyl)phenyl)dibenzo[b,d]furan-6-yl)phosphine oxide (DBFPO-Si) were designed and synthesized for high-performance phosphorescent OLEDs. Phosphine oxide, tetraphenylsilane, pyridine, and pyrimidine segments are introduced into the asym. position of a dibenzo[b,d]furan. DBFPO-Py, DBFPO-Pyr, and DBFPO-Si possess high thermal stability; high triplet energies of 2.96, 2.98, and 2.80 eV; and deep HOMO energy levels of -7.13, -7.23 and -7.07 eV;, resp. Blue phosphorescent OLEDs with DBFPO-Py, DBFPO-Pyr, and DBFPO-Si show low turn-on voltages, high current and power efficiencies, and superior external quantum efficiencies. Blue phosphorescent OLEDs with DBFPO-Py and DBFPO-Pyr showed improved performance in terms of current and power efficiencies, etc., compared with the device with 1,3-bis(3,5-dipyrid-3-yl-phenyl)benzene (BmPyPB), which is commonly used as a hole blocking layer. The blue phosphorescent OLEDs with DBFPO-Pyr showed the best performance with maximum external quantum efficiency of 23.6%, current efficiency of 29.8 cd A-1, power efficiency of 26.0 lm W-1, and low efficiency roll-off of 6.38%. Hole blocking materials based on asym. difunctionalized dibenzo[b,d]furan are expected to make a significant contribution to the development of blue phosphorescent OLEDs. The experimental part of the paper was very detailed, including the reaction process of Pyridin-3-ylboronic acid(cas: 1692-25-7Category: pyridine-derivatives)
Pyridin-3-ylboronic acid(cas: 1692-25-7) belongs to pyridine. Pyridine is very deactivated towards electrophilic substitution with respect to benzene. For this reason classical formylation, using methods such as the Gattermann or Vilsmeier reactions, are not generally successful. Category: pyridine-derivatives