Study on the Conductivity of a Sunset Yellow Dye-Based Natural Organic Device.

This manuscript studies the electrical conductivity of the natural organic compound sunset yellow (SY) dye. This dye shows good conductivity, which encourages us to further analyze the AC and DC conduction mechanism of a dye-based device. This dye was characterized by using x-ray diffraction and showed that SY dye has a high degree of crystallinity. The optical bandgap was characterized by the absorption spectroscopy measurement and it was found to be 2.34 eV. The DC electrical conductivity was measured with an impedance spectrometer from the temperature range 303 K (30°C) to 373 K (100°C) with 4 V bias voltage. The well-known Arrhenius diagram was drawn from the conductivity versus temperature plot to find the activation energy. The activation energy and the conductivity were measured to be 0.466 eV and 1.01 × 10 - 8 Ω - m - 1 for the low-temperature region and 0.683 eV and 6.18 × 10 - 8 Ω - m - 1 , respectively, for high-temperature regions. AC conductivity was also measured in the temperature range of 303 K (30°C) to 373 K (100°C) with a frequency variation range of 500 Hz to 100 kHz. The AC conductivity falls below DC conductivity in higher temperature regions. The value of activation energy for the AC field decreases with increasing frequency. The influence of the applied frequency on the conduction mechanism, which made hopping conduction the dominant mechanism, can be linked to this phenomenon. The correlated barrier hopping model (CBH) is evidence for the reduction of the activation energy in the AC electric field. The polaron binding energy is found to be 2.52 × 10 - 19 eV. We found an increase in density of the localized state around both sides of the Fermi level with the increase in temperature which increased the electrical conductivity. [ABSTRACT FROM AUTHOR]