Photovoltaic properties of the 4H-pyrano[3,2-c]quinoline derivatives and their applications in organic–inorganic photodiode fabrication

• Substitution group variation influenced absorbance.
• Substitution group variation influenced electrical parameters.
• Substitution group variation influenced photovoltaic parameters.
• Chlorophenyl as a substitution group improved the diode parameters.

‎2-Amino-6-ethyl-5-oxo-4-(3-Ph)-5, 6-dihydro-4H-pyrano[3,2-‎c]quinoline-3-carbonitrile (Ph-HPQ) and 2-Amino-4-(2-Cl)-6-ethyl-5-‎oxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile (Ch-HPQ) ‎films are deposited by using thermal evaporation technique. ‎ The absorbance of quinoline derivatives and the energy band diagrams of Ph-HPQ/p-Si and Ch-HPQ/p-Si devices are illustrated. The electrical properties of Au/Ph-HPQ/p-Si/Al and Au/Ch-HPQ/p-Si/Al heterojunction diodes are studied in terms of current–voltage characteristics. The two devices are fabricated with the same specifications. They showed a rectification behavior and photovoltaic properties in dark and under illumination conditions. The conduction mechanisms and diode parameters as a function of temperature of these devices are determined. The Schottky barrier height and the field lowering coefficients are also determined as a function of temperature. The photoconductivity sensitivity, short circuit current, open circuit voltage and the ratio between photocurrent to dark current are found to be a function of illumination intensity. The two devices satisfy the conditions to be used as photodiodes. The presence of the chlorophenyl as a substitution group improved the diode parameters.

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