Controlling of silicon–insulator–metal junction by organic semiconductor polymer thin film

Electrical and photovoltaic properties of a metal–semiconductor–insulator–polymer–metal diode were investigated. The n-Si/SiO2/MEH-PPV/Al diode shows a rectifying behavior with the rectification ratio of 2.22 × 105 at ±5 V and exhibits a non-ideal behavior due to the series resistance and oxide-organic layers. The organic semiconductor makes a contribution to the I–V characteristics of the diode and the trap-charge limited space charge and space charge limited current mechanisms were observed for the diode. The current–voltage characteristics of the n-Si/SiO2/MEH-PPV/Al diode under different illumination intensities give an open circuit voltage (Voc) along with a short circuit current (Isc). This suggests that the n-Si/SiO2/MEH-PPV/Al diode is a photovoltaic device with Voc = 0.456 V and Jsc = 7.89 × 10−8 A/cm2 values under 100 mW/cm2 illumination intensity. The photoconductivity mechanism of the diode is controlled by monomolecular recombination. The interface state density Dit values with time constant τit of the diode under dark and illumination conditions were found to be 2.53 × 1010 eV−1 cm−2 with 5.09 × 10−5 s and 2.50 × 1010 eV−1 cm−2 with 8.27 × 10−5 s, respectively. The obtained results indicate that the n-Si/SiO2/MEH-PPV/Al diode is a photo-sensitive diode.