X.-F. Wei, W.-Y. Tan, J.-H. Zou, Q.-X. Guo, D.-Y. Gao, D.-G. Ma, J. Peng, Y. Cao,
X.-H. Zhu, High Tg small-molecule phenanthroline derivatives as a potential universal
hole-blocking layer for high power-efficiency and stable organic light-emitting diodes,
J. Mater. Chem. C, 2017, 5, 2329-2336.