Dopant-induced states and charge-compensation pathways in doped Ni-deficient NiO

Determine, for doped Ni-deficient nickel oxide (NiOx) electrochromic materials, which electronic states are introduced or removed by specific substitutional dopants and whether the injected electron during cation insertion is compensated predominantly by nickel-cation redox, by dopant-cation redox, or by filling of vacancy-associated oxygen hole states.

Background

Electrochromic performance in Ni-deficient NiO is strongly influenced by defect chemistry and dopant incorporation, yet the mechanistic origins of dopant effects are often discussed only qualitatively (e.g., porosity or conductivity changes). This leaves key electronic-structure questions unresolved, particularly regarding how dopants modify defect states and participate in charge compensation.

Clarifying whether compensating electrons during alkali-ion insertion localize on Ni sites (Ni-centered redox), on the dopant (dopant-centered redox), or on oxygen hole states associated with Ni vacancies is essential for establishing predictive design rules for doped NiO-based electrochromic films.

References

These results collectively demonstrate that "doping improves NiO" is empirically true in many cases, yet the mechanistic origins are often discussed in broad terms (porosity, conductivity, more active sites), leaving unresolved which electronic states are introduced/removed by a dopant and whether injected charge is compensated by Ni-derived redox, dopant redox, or vacancy-derived hole states.

— Engineering Electrochromism in Ni-Deficient NiO through Defect, Dopant, and Strain Coupling  (2604.02952 - Jakovljević et al., 3 Apr 2026) in Section 1, Introduction