Iron Phthalocyanine(FePc)-Sensitized ZnO for Enhanced Photovoltaic and Electronic Performance

Iron phthalocyanine (FePc)-incorporated zinc oxide (ZnO) interfacial Al/p-Si Schottky barrier diodes (SBDs) have been fabricated by spin-coating methodology. The aim of this research was to evaluate the effect of FePc concentration variations on the electrical and photoresponsive properties of these heterojunction devices. The experimental process included current-voltage (I-V) characterisation over several FePc doping concentrations (0.05 wt%, 1 wt%, 2 wt%) under voltage ranges of ±5V and variable illumination conditions (from 10 mW/cm² to 100 mW/cm²). These measurements enabled the extraction of essential electrical properties, such as the ideality factor (n), barrier height (Φ B ), series resistance (Rs), shunt resistance (R sh ), and interface state density (N ss ), under both dark conditions and varying illumination intensities between 10 and 100 mW/cm². The observed increase in reverse current with increasing light intensity demonstrated the potential applications of these structures in photodetection technologies. The fabricated devices exhibited linear dynamic range (LDR) values of approximately 16 across all configurations which is a crucial factor for image sensors and achieved rectification ratios (RR) on the order of 10 3 . Experimental results showed that the rectification behaviour could be modulated by adjusting the FePc concentration. Furthermore, significant correlations were observed between FePc content and the values of n, Φ B , R s , R sh and N ss . Capacitance-voltage (C-V) and conductance-voltage (G-V) measurements were performed at 1 kHz and 1 MHz to extract additional parameters including diffusion potential (V D ), acceptor concentration (N A ), Fermi energy level (E F ) and depletion width (W D ). Frequency dependent capacitance behaviour was observed, with higher values recorded at lower frequencies due to the influence of interfacial states. The comprehensive analysis suggests that these FePc-doped structures hold considerable promise for optoelectronic applications, including photodetection and optical sensing, with performance characteristics that can be engineered by systematically modulating the FePc concentration within the ZnO interlayer framework.