Tetramer bis‐(8‐hydroxyquinoline) Zinc Crystals Prepared by Physical Vapor Deposition Method

Abstract

High quality single crystals of bis-(8-hydroxyquinoline) zinc (ZnQ 2 ), a π -conjugated molecular semiconductor with high thermal stability, good electron transport ability and excellent electroluminescence properties, were prepared by physical vapor deposition (PVD) method in a double zone tube furnace. X-ray single crystal diffraction (XSCD) indicates that the sample was ZnO 2 tetramer, (ZnQ 2 ) 4 , with the triclinic unit cell parameters: a = 10.8537(15)Å, b = 11.8814(16)Å, c = 13.0532(18)Å, α = 74.119(2)°, β = 73.449(2)°, γ = 70.999(2)°, volume = 1494.9(4)Å 3 and Z = 1. The crystallization mechanism analysis suggests a classical crystal growth process at low temperatures (300 and 320°C) and an existence of non-classical particle-attachment crystal growth pathway at high temperature (340°C). The (ZnQ 2 ) 4 crystals also show enhanced photoluminescence (PL) intensities and narrower full width at half maximum (FWHM) compared with that of the ZnQ 2 thin film.