Optical and electrical properties of porous silicon impregnated with Congo Red dye

Abstract

Incorporation of molecules into porous silicon (PS) matrix is of particular interest for potential utilization in hybrid organic-semiconductor devices. In this study, the incorporation of Congo Red molecules inside luminescent PS layers was investigated. The resulting structures have been characterized by Fourier Transformer Infrared (FTIR) and photoluminescence (PL) techniques. Based on these characterizations, the infiltration of dye molecules into the porous matrix has been proved. The recuperated PL signal was more important than that of porous silicon alone. A nonradiative excitation transfer due to dipolar interactions was evidenced from the effect of the CR concentration on the PL emission which was also confirmed by FTIR spectroscopy. It was found that the formed composite displays an efficient and stable PL. Preliminary characterizations of the electrical properties of the resulting nanocomposite structure have been also performed. The current–voltage (I–V) characteristics of CR-PS/p-Si were measured at the room temperature (300 K). To study the effect of illumination on CR-PS/p-Si composites, the measurement has been performed in dark and under illumination, at room temperature. The diode characteristics including zero-bias barrier height (ΦB0), ideality factor (n), and series resistance (Rs) were calculated at room temperature in dark and under illumination. The obtained results have shown that these characteristics are largely affected by illumination. The incorporation of dye molecules in porous silicon matrix enhanced photovoltaic properties of resulting structures.