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Abstract Colloidal nanocrystals (NCs) can be used to prepare high-color-purity metal halide perovskites (MHPs) for light-emitting displays. However, the NCs have a finite particle-size distribution, which broadens the linewidth of photoluminescence spectra under strong quantum confinement, and thereby degrades the color purity of the MHPs. This paper presents a simple method to quantify this externally-introduced broadening of linewidth $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{SD}}}}}}}$$ Γ SD by combining experimental size-distribution histogram with size-dependent photoluminescence-wavelength (PL- $${{{{{\boldsymbol{\lambda }}}}}}$$ λ ) curve. We develop a semi-empirical method to estimate the other three contributions to the experimentally-measured full-width at half-maximum, $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{EXP}}}}}}}$$ Γ EXP . Namely: the intrinsic linewidth $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{LO}}}}}}}$$ Γ LO caused by exciton-longitudinal optical (LO) phonon Fröhlich coupling; the inhomogeneous linewidth $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{o}}}}}}}$$ Γ o caused by imperfections-related scattering, and the broadening $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{QC}}}}}}}$$ Γ QC due to the quantum-confinement effect. We show that $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{LO}}}}}}}$$ Γ LO of a nanocrystal decreases together with the particle size, disappearing at 1.6 nm radius. Finally, we show that $${{{{{{\boldsymbol{\Gamma }}}}}}}_{{{{{{\bf{LO}}}}}}}$$ Γ LO is correlated with the degree of Fröhlich-polaron formation, hence proportional to the long-range LO-phonon-electron coupling.

Ion migration can induce overshoot of luminance in normal 3D perovskite light-emitting diode devices and results in reduced lifetime. Here Kim et al. show that the ion migration and overshoot can be suppressed in 3D/2D hybrid perovskites, leading to 21 times longer operational lifetime.

Dispersion of metallic nanoparticles is promising for energy conversion and storage, but gaining control of size and distribution is not trivial. Here the authors use lattice mismatch to manipulate exsolution of nanoparticles, achieving a high population of small nanoparticles in perovskite thin films.

Abstract We report direct evidence that oxygen vacancies affect the structural and electrical parameters in tensile-strained NdNiO3−δ epitaxial thin films by elaborately adjusting the amount of oxygen deficiency (δ) with changing growth temperature T D. The modulation in tensile strain and T D tended to increase oxygen deficiency (δ) in NdNiO3−δ thin films; this process relieves tensile strain of the thin film by oxygen vacancy incorporation. The oxygen deficiency is directly correlated with unit-cell volume and the metal-insulator transition temperature (T MI), i.e., resulting in the increase of both unit-cell volume and metal-insulator transition temperature as oxygen vacancies are incorporated. Our study suggests that the intrinsic defect sensitively influences both structural and electronic properties, and provides useful knobs for tailoring correlation-induced properties in complex oxides.

The original version of this Article contained an error in the Data Availability section, which incorrectly read ‘The data that support the findings of this study are available from the corresponding authors upon request.’ The correct version replaces this sentence with ‘The research data underpinning this publication can be accessed at https://doi.org/10.17630/21d12144-58ef-4f82-acd0-ba3c9a44ed72’. This has been corrected in both the PDF and HTML versions of the Article.