Photo- and electro-active amorphous molecular materials: morphology, structures, and hole transport properties of tri(biphenyl-4-yl)amine

Tri(biphenyl-4-yl)amine is found to constitute a new class of photo- and electro-active amorphous molecular materials. The material readily forms an amorphous glass with a glass-transition temperature of 76 °C, as characterized by differential scanning calorimetry, X-ray diffraction and Raman spectroscopy. Its glass-forming properties are discussed in the light of its molecular and crystal structures determined by X-ray crystallography. The material in the glassy state shows a relatively high hole drift mobility of 1.5 × 10–4 cm–2 V–1 s–1 at an electric field of 2 × 105 V cm–1 at 20 °C. Temperature and electric-field dependencies of the hole drift mobility in the glassy state of TBA are discussed.