Doping effect of viologen on rectification, charge transport processes andphotovoltaic properties of furazano (3,4-b)piperazine thin film device

The electrical and photoelectrical properties of a sandwich junction device based on allyl viologen (AV)-doped furazano (3,4-b)piperazine (FP) having structure ln/AV : FP/ITO have been reported. A significant enhancement in t he rectification, dark conductivity and photovoltaic response has been obse rved in AV-doped FP devices compared with undoped FP devices. The present c ommunication deals with the charge transport mechanism and photogeneration process in ITO/AV doped FP/ln Schottky devices. The J-V characteristics rec orded in the dark show a rectification effect due to the formation of a bar rier at the AV-doped FP/ln interface. Impedance spectroscopy has been used to study the charge transport mechanism for AV-doped FP and its interface w ith ln. The bulk and junction resistance along with capacitance were determ ined by analyzing their contribution at an individual level. Doping imparts an improvement in photoresponse of FP as well as an abundance of photoexci ted species at the interface. (C) 2001 Kluwer Academic Publishers.