Characterization of Flexible Organic-Inorganic Photovoltaic Device Material

Abstract

Presented is the results of a study using density functional theory of the electrical characteristics of copper-doped nickel (Cu:NiO) and nickel oxide (NiO), and their performances when utilized as Hole Transport Layer (HTL) in photovoltaic (PV) devices by modelling their I-V characteristics is presented. From first-principle it was observed that, doping NiO with a Cu ion introduced more states in the valence band enhancing the charge transport property of the material. The band gap of NiO reduced from 3.04 eV to 2.63 eV in the unstable supercell structure of Cu:NiO and then to 1.65 eV in the stable supercell structure of Cu:NiO. The defect created by the substitution of Cu ion for Ni ion appears to have given rise to additional electronic states near the bandgap which increases the conductivity of holes substantially. Both stable and unstable supercell structures of Cu:NiO showed a direct band gap which eases the transition of holes from the active layer to the HTL. There was also a shift in Fermi level towards the valence band in both stable and unstable supercell structures thus enhancing hole mobility in the HTL. The unstable Cu:NiO showed the highest efficiencies when used as a composite HTL with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as compared to PEDOT:PSS/NiO, PEDOT:PSS and PEDOT:PSS/Cu:NiO (stable). This demonstrates how the HTL enhances device performance in applications for organic-inorganic electronic devices and provides a better knowledge of its electrical characteristics.