Electrical transport mechanisms and photovoltaic characterization of cobalt phthalocyanine on silicon heterojunctions

Heterojunction devices were fabricated by growing cobalt phthalocyanine, CoPc, films onto p-type Si using the conventional thermal evaporation technique. The dark current–voltage (I–V) measurements were performed in the temperature range 300 to 393 K. The measured electrical parameters were used to determine the conduction mechanisms of these heterojunctions. The forward current was found to be increased exponentially with the applied voltage in the region of V ≤ 0.4 V, which was dominated by the thermionic emission over the CoPc/p-Si interface. In the region 0.5 < V ≤ 1 V, the current transport was due to the space-charge-limited current controlled by an exponential trap distribution in the band gap of CoPc. A free carrier concentration of 1.8 × 1015 cm− 3, built-in potential of 0.28 V and a maximum barrier field of 2.5 × 103 V/cm were estimated from the dark capacitance–voltage measurements at 1 MHz. From the current–voltage characteristics under illumination and then photovoltaic properties of Au/CoPc/p-Si solar cell are evaluated.