Electrical and photosensing performance of heterojunction device based on organic thin film structure

• The junction of Au/AlPcCl/PTCDI/ITO exhibit rectifying characteristic showing a p–n diode like behavior.
• High photosensitivity for the device is observed.
• The device shows an improvement in photovoltaic parameters.
• The interface states density is not effective on the device performance characteristics under high frequency.

In this work, the heterojunction thin films of aluminum phthalocyanine chloride on N,N′-dioctyl-3,4,9,10-perylenedicarboximide device was fabricated by using thermal evaporation technique under high vacuum (∼10−4 Pa). The morphology of the device was characterized by scanning electron microscopy (SEM). The dark current density–voltage (J–V), capacitance–frequency (C–f) and conductance measurements at different temperatures in the range 300–425 K were performed to determine the electrical properties of the device. The exponent of the light intensity dependence for the short-circuit photocurrent (Jsc) of the device indicates the presence of continuous distribution of traps. The device showed improvement in the open circuit voltage as compared to other organic compounds. The photosensitivity of the device was calculated and found to be 3.1 at ±1 V under illumination intensity of 100 mW/cm2. This suggested that the device shows a photodiode characteristic. The interface state density of the device was determined using the conductance technique and was found to be low which suggested that the interface states at this density range are not effective on the device characteristics which supports the efficient properties for the studied device.

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