Fabrication and electrical characterization of n-1,3,3-trimethylindolino-β-naphthopyrylospiran/p-Si (organic/inorganic) heterojunction for application in photovoltaic device

Abstract

1,3,3-Trimethylindolino-β-naphthopyrylospiran (SO) thin film was prepared using conventional thermal evaporation techniques onto P-Si single crystal substrate to fabricate n-SO/P-Si heterojunction. The dark current–voltage (I–V) characterization and its temperature dependence in forward and reverse bias were investigated. This characteristic suggests that the forward conduction was dominated by thermionic-emission and space-charge-limited current (SCLC) mechanisms at low, (Vf ≤ 0.2 V), and high, (0.5 ≤ Vf ≤ 1.5 V), voltage, respectively. In addition, the current-voltage characteristics allow us to extract some characteristic important parameters of diode such as the series resistance, Rs, shunt resistance, Rsh, quality factor, n, and the barrier height, φ. Furthermore, the dark room temperature C–V characteristics was investigated to estimate the values of the junction built-in potential at 1 MHz and the charge carrier concentration. In addition, the device showed strong photovoltaic characteristics under constant illumination of 5 mW/cm2 at room temperature, with parameter values 0.6 V, 56.6 mA/cm2, 0.32% and ∼1.2% for open circuit voltage, Voc, the short circuit current density, Jsc, the fill factor, FF, and conversion efficiency, η, respectively.