Photovoltaic performance analysis of organic device based on PTCDA/n-Si heterojunction

Thin films of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) were prepared by thermal evaporation technique under high vacuum at room temperature (300 K). The prepared films were identified by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The capacitance–voltage (C–V) characteristics of PTCDA/n-Si heterojunction was measured at different temperatures ranging from 300 to 400 K under dark condition. The dependence of C−2 on V for the device PTCDA/n-Si was found to be almost linear which indicates that the junction is abrupt and then the essential junction parameters were obtained. The built-in potential and the acceptor carrier concentration are found to be strongly temperature dependent. Capacitance was also measured under illumination of 100 mW/cm2 condition in the temperature range 300–400 K. The capacitance of the device is found to increase with increasing illumination intensity due to the irradiated light induced electron–hole pairs in the depletion region as well as the decrease in the depletion layer. The dark current density–voltage (J–V) characteristics show the rectification effect which may be due to the formation of junction barrier at PTCDA/n-Si interface. The photovoltaic characteristics were determined by analyzing the dependence of short circuit photocurrent density JSC and the open circuit voltage Voc on the illumination intensity at different temperatures. PTCDA is useful material to be used in photovoltaic devices.