Hole transport layers deposited by magnetron sputtering

Abstract

Nickel oxide films have been widely studied as hole transport layers in perovskite solar cells because they present good chemical stability and nickel is abundant in nature. In this study, films were deposited using Magnetron Sputtering with a pulsed source. The NiOx films were deposited over an aluminum zinc oxide (AZO) film, which is non-toxic and cheap. The effects of varying the pulse duration on the deposition rate, film chemical composition, structure, optical and electrical characteristics were investigated. Films were produced in a chamber with pressures ranging from 3.06 to 4.01 mTorr. To activate the plasma, a 1500 VA, 600 V transformer was used, along with a 1.5 kVA/220 V single-phase voltage. Energy dispersive X-ray spectroscopy (EDS) was used to determine the chemical composition of the NiO_x films. Scanning electron microscopy (SEM) was employed to analyze surface defects of the films. X-ray diffraction showed peaks at 34.20° and 72.28°, indicating the crystalline structure of nickel oxide. Optical properties of the films were obtained from UV-Vis-NIR spectra in the 200 to 2500 nm range. Films deposited with low pulses with 50 and 60 µs had transmittances of between 89 and 91% in the near infrared region. From the transmittance and reflectance data, the optical gap energies were calculated, which varied from 3.38 to 3.70 eV. In addition, the Urbach energy varied from 0.348 to 0.625 eV.

DOI: 10.56238/sevenIIImulti2023-028