Electrical transport mechanisms and photovoltaic characteristics of Au/neutral red/p-Si/Al heterojunction solar cell

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Uniform thin films of neutral red, NR, have been successfully prepared by  thermalevaporation technique. X-ray

diffraction patterns showed that the structure of NR film consists of nanocrystallites dispersed in amorphous matrix.
Increasing annealing temperature influences crystallite size and quantity of amorphous phase. The high absorption
of NR films in visible region of spectra supports the application of NR film as an absorber in photovoltaic
devices. Hybrid organic–inorganic heterojunction solar cell, Au/NR/p-Si/Al, was fabricated. The current–voltage
characteristics of the heterojunction diode have been studied in the temperature range of 300–355 K and in
the voltage range (−2 to 2 V). The device showed a series resistance of 2.64 kΩ, shunt resistance of 237 kΩ, rectification
ratio of 106 at ±1 V and ideality factor of 1.8 at room temperature. It was found that the conduction
mechanisms of the diode are controlled by the thermionic emission at forward voltage bias ≤0.2 V and space
charge limited current (SCLC) conduction in the voltage range 0.2 b V ≤ 2 V. The capacitance–voltage characteristics
of theNR/p-Si devicewere studied at roomtemperature in dark condition. Energy band diagramfor NR/p-Si
device was constructed. The device under illumination with light of intensity 20mW/cm2 gives values of photovoltaic
parameters as: open circuit voltage (Voc), short circuit current (Isc), fill factor (FF) and power conversion
efficiency (η) are 0.46 V, 1.78 mA, 0.29 and 2.37%, respectively.