Engineered optical and electrical performance of rf–sputtered undoped nickel oxide thin films for inverted perovskite solar cells

Abstract

Inverted perovskite solar cells incorporating RF sputtered NiO thin films as a hole transport layer and window layer are demonstrated. The electrical and optical properties of the NiO thin films are engineered using varied sputtering conditions. The localized states within bandgap owing to its crystal disorder and nonstoichiometric features affect the transmittance and the optical bandgap of the NiO thin films which in turn influences the Jsc of the perovskite solar cells. In addition, the electrical properties of the NiO thin films can be also varied during sputtering condition affecting the concentration of nickel vacancies and the resulting hole concentration. The conductivity largely originates from the hole concentration relating to the density of states in the NiO thin films which influence the fill factor (FF) of the solar cells. The solar cells fabricated with the NiO thin films made at 4 Pa of deposition pressure show highest performance owing to excellent transmittance and wider bandgap along with moderate conductivity. With further optimization, the perovskite solar cells exhibit ~20 mA/cm2 of Jsc and a 12.4% PCE (11.3% of averaged PCE).

Application-Specific Oxide-Based and Metal–Dielectric Thin-Film Materials Prepared by Radio Frequency Magnetron Sputtering

“…Sputtering processes allow thin-film materials to be deposited either on bare substrates or on top of any structured systems, e.g., photonic or magneto-photonic crystals, usually without having any unpredictable thickness uniformity or stoichiometry issues with the grown films. Thin-film materials, especially radio frequency (RF) magnetron-sputtered thin films, were originally considered useful mainly in electronics and semiconductor devices; however, sputtered thin films have also been found to be applicable within a wide range of fields, such as optoelectronics, energy, mechanical/chemical, optical coatings, life sciences, and others [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]. In this nanotechnological era, the sputter deposition of thin films becomes a rather ubiquitous and actively growing field of human endeavour, integrating the fundamental and important scientific areas of research, process development, deposition system design, and new product manufacturing.…”

Electrochemical behavior of spray deposited nickel oxide (NiO) thin film in Alkaline electrolyte

“…For several years, transition metal oxides have attracted a noticeable attention of researchers due to their promising characteristics for various application fields. Among these materials, nickel oxide (NiO) is an attractive material because of its good magnetic, thermal, optical, mechanical and, electrical performance [1], [2], [3]. The stoichiometric NiO crystal is an insulator, whereas the conductivity can be enhanced in pure NiO by creating Ni vacancies [4].…”

Fabrication of p-NiO/n-TiO2 Solar Device for Photovoltaic Application

“…This has made researchers tune the conductivity and energy level of NiO to allow usage in solar cell fabrication, including usage for hole transport and window layer. Although the bandgap of NiO is high compared to silicon and ZnO, there has been the usage of NiO for hole transport and as a window layer [15][16][17]. The bandgap of about 3.5 eV to 4.0 eV and suitability of NiO as a p-type solar cells material has endeared it [18].…”