Nickel Oxide for Perovskite Photovoltaic Cells

Abstract

Organic–inorganic perovskite solar cells (PSCs) have shown tremendous progress from 3.8% power conversion efficiency (PCE) in 2003 to 25.2% in 2020 because of their wide range of light absorption, fast charge separation, long carrier diffusion length, and long carrier lifetime. The optoelectronic characteristics of hole transport material (HTM) and electron transport material (ETM) strongly affect photovoltaic (PV) performance and stability of PSCs. Recently, various inorganic HTMs with high efficiency, stability, and cost‐effectiveness have been investigated. Among them, nickel oxide (NiO x ) is one of the most studied inorganic HTMs in terms of device performance and stability because it has high hole mobility, electrical conductivity, transmittance, and energetically favorable band alignment, along with environmental stability. This article overviews the recent progress on NiO x ‐based planar PSCs. The main focus is on the structural, electrical and optical properties of the NiO x thin film, which mainly depends on the synthesis methods and post‐treatments. Firstly, a variety of methods are investigated to fabricate dense, compact and high crystallized NiO x thin film. Moreover, multifarious doping strategies and surface functionalization using organic materials are summarized as approaches to improve their properties for realizing high performance p–i–n planar PSC devices.

Imaging and quantifying non-radiative losses at 23% efficient inverted perovskite solar cells interfaces

“…Importantly, the time-resolved analysis also proves that high non-radiative recombination is responsible for the fast decay of the reference cell of Fig. 2d , that therefore cannot be attributed to carrier extraction as sometimes reported in the literature 31 , 32 .…”

Microwave-facilitated crystal growth of defect-passivated triple-cation metal halide perovskites toward efficient solar cells

“…Another factor limiting V oc is the band offset of the valence band maximum between perovskites and NiO x , which shrinks the quasi-Fermi-level splitting. 67,68 Thus, this energy level misalignment limits the further increase in V oc despite the low defect density in the MWA-TOPO film.…”

Organic Hole‐Transport Layers for Efficient, Stable, and Scalable Inverted Perovskite Solar Cells

“…Although inorganic HTLs (such as NiO x ) possess a high thermal stability and transparency, [ 68–70 ] their PV performance is usually inferior to their organic counterparts due to relatively a low intrinsic conductivity and surface defects. [ 71,72 ] For instance, it was reported that NiO x Ni ≥3+ surface species can react with perovskite organoiodide precursors, resulting in a defective NiO x /perovskite interface. [ 73 ] Besides, most of the inorganic HTLs require either a high‐temperature or high‐vacuum processing step and may feature a poor wettability with respect to the perovskite precursor ink, in case of solution processing.…”