Performance of inverted organic photovoltaic cells with nitrogen doped TiO2 films by atomic layer deposition

Abstract

Atomic layer deposition (ALD) was used to synthesize titanium oxide (TiO2) film as an electron transport layer (ETL) in inverted organic photovoltaic cells (IOPVs). By adjusting the ALD precursor ratio and deposition temperature, the thickness of the TiO2 film was 5 nm, and its effect on the photovoltaic performances was evaluated. We also investigated the effect of nitrogen doping of TiO2 on the power conversion efficiency (PCE) of the cells. An IOPV cell fabricated with a 0.6%-nitrogen-doped TiO2 (N-TiO2 A) ETL exhibited a PCE of 2.27%, which is a 6% increase compared with an equivalent cell containing an undoped TiO2 ETL. Furthermore, the XPS results confirmed the doping of nitrogen into the samples. The doping improved the electrical properties of the TiO2 films evidenced by the Hall measurements in terms of conductivity, hall electron mobility and carrier density.