Study of the effect of trap levels on steady-state dark I–V characteristics in Safranine-T-based solid-state thin film photoelectrochemical cell

Abstract

In this work we describe the steady-state current–voltage (I –V) characteristic of solid-state photoelectrochemical cells (PEC). The cell contains a blend made of Safranine-T dye dispersed in polyvinyl alcohol (PVA), polyethylene oxide (PEO) complexed with ammonium perchlorate (NH4ClO4), ethylene carbonate (EC) and propylene carbonate (PC). A thin film (20 μm) of this blend is sandwiched between two transparent indium-tin-oxide (ITO)-coated glass plates, which act as the two contact electrodes. Addition of ion salt in the active materials alters the device characteristics in a significant way. In the present work we have concentrated on the steady-state dark I –V characteristics of the device. The trap-assisted charge carrier transport model is used to satisfactorily describe the I –V characteristics. The experimental results are explained by the transport of carriers having traps with exponential distribution. The characteristic temperature of the traps and trap energy level have been estimated to be 1164 K and 0.1 eV, respectively, within the experimental limit. The present experimental data will be helpful to understand the steady-state operation of a photoelectrochemical cell.