Photovoltaic properties of the organic-inorganic photodiode based on polymer and fullerene blend for optical sensors

Inorganic-organic photodiode was fabricated with blend single layer as well as sandwich structure, using p-Si and poly(2-methoxy-5-(20-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV):fullerene-C-60 blend. Electronic parameters such as barrier height, diode ideality factor, series resistance and shunt resistance were determined from the I-V characteristic in the dark of p-Si/C-60:MEH-PPV diode and were found to be 0.75 eV, 1.36, 6.26 x 10(5) Omega, 1.40 x 10(10) Omega, respectively. The interface state density and time constant of p-SVC60:MEH-PPV diode were determined to be 2.55 x 10(11) eV(-1) cm(-2) and 1.81 X 10(-6) s, respectively. The photoconductivity sensitivity and responsivity values of the diode were found to be 8.16 x 10(-6) S m/W and 1.63 x 10(-2) A/W, respectively. The p-Si/C-60:MEH-PPV diode indicates a photovoltaic behaviour with a maximum open circuit voltage V-oc of 130mV and short-circuit current I-sc of 24.5 nA. The photocurrent of the device was found to be 2.94 mu A and photoconductivity mechanism of the p-Si/C60:MEH-PPV diode indicates the existence of continuous distribution of trap centres. It is evaluated that the p-Si/C-60:MEH-PPV photovoltaic device can be operated as a heterojunction photodiode. (C) 2007 Elsevier B.V. All rights reserved.