NiN-Passivated NiO Hole-Transport Layer Improves Halide Perovskite-Based Solar Cell

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Interfaces between inorganic selective contacts and halide perovskites (HaPs) are critical for stable and reproducible solar cells.
• Nickel oxide (NiO) is a promising hole-transport layer for HaP solar cells due to its stability, low cost, and suitable electronic structure.
• Scalable fabrication of HaP-based solar cells (PSCs) using vacuum deposition methods is hindered by interface control issues.

Purpose of the Study:

• To improve the stability and efficiency of PSCs by addressing the challenges at the NiO/HaP interface.
• To investigate the protective and passivating effects of a novel nickel nitride (NiN) layer deposited via RF sputtering.
• To enable scalable, solvent-free, vacuum-deposited PSC fabrication.

Main Methods:

• Fabrication of NiO using RF sputtering.
• Deposition of a NiN layer onto NiO without breaking vacuum.
• Characterization of the NiN layer's protective effect on NiO conductivity during Ar plasma exposure.
• Evaluation of the NiN layer's interface passivation capabilities between NiO and HaPs.
• Fabrication and testing of PSC devices with and without the NiN layer.

Main Results:

• The NiN layer effectively prevented the reduction of Ni³⁺ to Ni²⁺ in NiO by Ar plasma, preserving its conductivity.
• The NiN layer successfully passivated the NiO/HaP interface, enhancing PSC stability.
• PSC efficiency increased from an average of 16.5% (17.4% record) to 19% (19.8% record) with the NiN layer.
• Device stability was significantly improved by the incorporation of the NiN layer.

Conclusions:

• The NiN layer provides a dual protective mechanism for NiO, maintaining conductivity and passivating the interface.
• This approach offers a viable strategy for developing stable, efficient, and scalable PSCs using vacuum deposition.
• The developed method addresses a key challenge in HaP solar cell technology, paving the way for commercialization.