Tin-based halide perovskites (ASnX3) have garnered substantial interest due to their unique photoelectric properties and environmentally friendly features. The A-site ions tuning strategy has been proven to promote material performance. However, there is a lack of systematic research on the optical properties, lattice structure variation, and band structure evolution in tin-based perovskites when the A-site ions tune from organic to inorganic. Herein, MA1-xCsxSnBr3 and MA1-xCsxSnI3 (0 <= x <= 1) flakes are synthesized through a one-pot reaction method. By controlling the Cs ratio, a tunable photoluminescence (PL) emission covering a wide range of 560-685 nm can be observed in MA1-xCsxSnBr3, with bandgap tuned from 1.8 to 2.15 eV, while the PL ranges from 900 to 950 nm with the bandgap 1.2-1.3 eV for MA1-xCsxSnI3. Besides, the PL intensity of MA1-xCsxSnBr3 significantly enhances with the increasing Cs ratio. First-principles calculations reveal that the octahedron shrinks gradually as the Cs ratio increases. It increases the orbital overlap between Sn and Br and causes a symmetry variation, thus decreasing the bandgap and increasing emission intensity. This work reveals the photophysical mechanism of improved optical properties and bandgap variation in tin-based perovskites, paving the way for their future applications.

The dangling bonds and surface defects at the grain boundaries of three-dimensional (3D) perovskite provide convenient conditions for non-radiative recombination and ion migration, which degrades the stability of perovskite materials. Herein, we prepared single-component lateral epitaxial heterostructure perovskites using a one-step solution method by rare earth Er3+ doping. Through photoluminescence (PL) and time-resolved PL spectroscopy, the erbium-doped CsPb(BrxI1−x)3 heterostructure microplate forms a stable dual-wavelength emission with enhanced PL intensity and lifetime. We find that rare earth doping can effectively suppress ion migration by improving the ion migration barrier and facilitating the intrinsic stable heterostructure formation with desired dual-wavelength emission and improved radiation recombination rate. The discovery sheds a new perspective on inhibiting ion migration by trivalent B-site doping of rare earth ions and provides a basis for the preparation of single-component heterostructure perovskite.

By controlling the growth temperature and increasing Er-doping concentration in CsPbCl 3 x Br 3(1− x ) :Er, their emitted PL can be tuned from red (1.82 eV) to near-infrared (1.53 eV) while keeping their intrinsic bandgap without significant variation.

The realization of stable single-component white light emission in metal halide perovskites is still challenging due to the fast halide ion migration and narrow luminescence bands. In this work, all-inorganic single CsPbClxBr3-x perovskite microplates with stable red-blue-green triple color light emission are prepared by introducing europium ions Eu3+ as dopants. Eu doping effectively suppresses ion migration and enables two spatially separated halide phases with stable dual-wavelength emissions. Furthermore, the incorporation of Eu3+ compensates for the absence of red-light emission, thereby yielding a superior white emission with exceptional quality. The color rendering index of triple-color-emitting perovskites can be tuned successfully by controlling the halogen ratios, and the optimal microplate achieved a Commissions Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32). The results present a new enlightenment for the preparation of low-cost single-component white light materials.

While high-reflectivity end faces have been used as resonant cavities to achieve low-threshold lasing in various micro-nano structures of all-inorganic perovskites, the specific influence of the natural surface cavity of a sample on its optical properties has rarely been reported. Herein, we systematically investigate the effect of interference effect induced by the surface cavity of wedge-shaped microplates on their optical properties. The competition between interference and re-absorption effects causes oscillation shifts in the fluorescence spectrum and the formation of interference fringes. Variations in the microplate’s thickness have a considerable impact on the interference effect, modifying the sample’s optical properties.