Effect of Acid Doping on Junction Characteristics of ITO/Polyaniline/N719/Ag Diode

In this paper, we demonstrate the fabrication and electrical characterization of a heterojunction Schottky diode between polyaniline (PANI) and a ruthenium-based organic semiconductor (N719). In this system, PANI behaves as an organic p-type conducting polymer while N719 acts as an n-type semiconductor. The fabrication was carried out using different methods to deposit each component: solution casting for PANI, spray coating for N719, and screen-printing for silver paste. The PANI film was doped by soaking it in HCl solutions of different concentrations to form emeraldine salt, i.e., a conductive type of PANI. Electrical characterizations of PANI and the diode were performed using conductivity and current density–voltage (J–V) measurements. The maximum conductivity of PANI was obtained at 3.18 × 10−2 S/cm using an HCl concentration of 1 M. The fabricated diode exhibited a low Schottky barrier (ΦB = 0.48 eV) and rectifying behavior (γ ∼ 9) with moderate ideality factor (η ∼ 8). Acid doping of PANI caused better diode performance and an increase in current density by four orders of magnitude.