Synthesis of a new 1,3,4-thiadiazole-substituted phenanthroimidazole derivative, its growth on glass/ITO as a thin film and analysis of some surface and optoelectronic properties

Abstract

A new phenanthroimidazole derivative (PMItz) bearing a 1,3,4-thiadiazole moiety was prepared and deposited as a thin film on a previously prepared glass/ITO substrate via the physical vapor deposition (PVD) method. The optical and surface morphological properties of the fabricated thin film, glass/ITO/PMItz, were investigated via UV-Vis spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Subsequently, metal/ITO/PMItz/metal (metal: In and Ag) devices were fabricated and their electrical properties were investigated. The optical measurements revealed the reasonably high optical conductivities of the thin films. The energy band gap was calculated to be 2.96 eV, the absorption coefficient was calculated to be 1.3 × 10⁶ m⁻¹ and the optical conductivity was calculated to be 3.14 × 10¹⁴. The typical diode characteristics of the devices were demonstrated by electrical measurements. The current–voltage (I–V) measurements revealed that the devices exhibited photo-sensitivity, the photovoltaic effect and strong negative differential resistance (NDR) effect at certain voltage values. The ideality factors in the dark were calculated to be 2.4 and 2.54 for the In/ITO/PMItz/In and Ag/ITO/PMItz/Ag devices, respectively. According to the Hall effect measurements, the conductivity of PMItz was found to be p-type with high carrier mobility and concentration and low specific resistance.