Molecular design of high-molecular-orientation electron-transport materials and application to organic light-emitting diodes

Two novel electron-transport materials (ETMs), 2,3′-Bpy- TP and 2,4′-Bpy-TP, with high horizontal molecular orientation to substrates, were synthesized. It was shown by measuring the IR absorption spectra of their deposited thin films that C-H N hydrogen bonds are formed between the 2,3′-Bpy-TP molecules and between the 2,4′-Bpy-TP molecules. It was also shown that there is a closed relationship between their molecular orientations and the driving voltages of electron-only devices (EODs) using them as electron-transport layers (ETLs).