Effect of substitution group on dielectric properties of 4H-pyrano [3,2-c] quinoline derivatives thin films

• Published in: Chinese physics B 2016-07, Vol.25 (7), p.440-449
• Main Author: H M Zeyada F M El-Taweel M M El-Nahass M M El-Shabaan
• Format: Article
• Language: English
• Subjects: correlated barrier hopping; dielectrical properties; Nyquist图; quinoline derivatives; thin films; 交流电导率; 介电性质; 取代基效应; 喹啉; 温度范围; 生物薄膜; 高介电常数
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/25/7/077701

The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-（3-phenoxyphenyl）-5,6-dihydro-4H-pyrano[3, 2-c]quinoline-3-carbonitrile（Ph-HPQ） and 2-amino-4-（2-chlorophenyl）-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3, 2-c] quinoline-3-carbonitrile（Ch-HPQ） thin films were determined in the frequency range of 0.5 k Hz–5 MHz and the temperature range of 290–443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping（CBH） mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-HPQ and Ch-HPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-HPQ films have higher impedance than the Ph-HPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-HPQ has higher dielectric constants than the Ch-HPQ.