Reducing environmental impact is a key challenge for perovskite optoelectronics, as most high-performance devices are based on potentially toxic lead-halide perovskites. For photovoltaic solar cells, tin-lead (Sn–Pb) perovskite materials provide a promising solution for reducing toxicity. However, Sn–Pb perovskites typically exhibit low luminescence efficiencies, and are not ideal for light-emitting applications. Here we demonstrate highly luminescent germanium-lead (Ge–Pb) perovskite films with photoluminescence quantum efficiencies (PLQEs) of up to ~71%, showing a considerable relative improvement of ~34% over similarly prepared Ge-free, Pb-based perovskite films. In our initial demonstration of Ge–Pb perovskite LEDs, we achieve external quantum efficiencies (EQEs) of up to ~13.1% at high brightness (~1900 cd m⁻²), a step forward for reduced-toxicity perovskite LEDs. Our findings offer a new solution for developing eco-friendly light-emitting technologies based on perovskite semiconductors.

All-inorganic cesium lead bromide demonstrates better thermal and chemical stability compared to its hybrid counterparts, and thus it can provide a base for high stability and performance of CsPbBr₃-based perovskite light emitting diodes (PeLEDs).

Molecular chelation-driven interface engineering employs polar groups to lower water activity by H-bond reorganization and Zn ²⁺ chelation, forming a PSZ/inorganic SEI hybrid layer that enables adaptive corrosion protection and suppressed degradation.

The ordered double-perovskite $\mathrm{S}{\mathrm{r}}_2\mathrm{FeMo}{\mathrm{O}}_6$ (SFMO) possesses remarkable room-temperature low-field colossal magnetoresistivity and transport properties which are related, at least in part, to combined structural and magnetic instabilities that are responsible for a cubic-tetragonal phase transition near 420 K. A formal strain analysis combined with measurements of elastic properties from resonant ultrasound spectroscopy reveal a system with weak biquadratic coupling between two order parameters belonging to ${\mathrm{\Gamma }}_4^{+}$ and $m{\mathrm{\Gamma }}_4^{+}$ of parent space group $Fm\overline{3}m$. The observed softening of the shear modulus by ∼50% is due to the classical effects of strain/order parameter coupling at an improper ferroelastic $\left({\mathrm{\Gamma }}_4^{+}\right)$ transition which is second order in character, while the ferromagnetic order parameter $\left(m{\mathrm{\Gamma }}_4^{+}\right)$ couples only with volume strain. The influence of a third order parameter, for ordering of Fe and Mo on crystallographic B sites, is to change the strength of coupling between the ${\mathrm{\Gamma }}_4^{+}$ order parameter and the tetragonal shear strain due to the influence of changes in local strain heterogeneity at a unit cell scale. High anelastic loss below the transition point reveals the presence of mobile ferroelastic twin walls which become pinned by oxygen vacancies in a temperature interval near 340 K. The twin walls must be both ferroelastic and ferromagnetic, but due to the weak coupling between the magnetic and structural order parameters it should be possible to pull them apart with a weak magnetic field. These insights into the role of strain coupling and relaxational effects in a system with only weak coupling between three order parameters allow rationalization and prediction of how static and dynamic properties of the material might be tuned in thin film form by choice of strain contrast with a substrate.