Phase-pure CsSnI₃, FASnI₃, Cs(PbSn)I₃, FA(PbSn)I₃ perovskites (FA = formamidinium = HC(NH₂)₂ ⁺) as well as the analogous so-called vacancy-ordered double perovskites Cs₂SnI₆ and FA₂SnI₆ are mechanochemically synthesized. The addition of SnF₂ is found to be crucial for the synthesis of Cs-containing perovskites but unnecessary for hybrid ones. All compounds show an absorption onset in the near-infrared (NIR) region, which makes them especially relevant for photovoltaic applications. The addition of Pb(II) and SnF₂ is crucial to improve the electronic properties in 3D Sn(II)-based perovskites, in particular their charge carriers mobility (≈0.2 cm² Vs⁻¹) which is enhanced upon reduction of the dark carrier conductivity. Stokes-shifted photoluminescence is observed on dry powders of Sn(II)-based perovskites, which makes these materials promising for light-emitting and sensing applications. Thermal stability of all compounds is examined, revealing no significant degradation up to at least 200 °C. This meets the requirements for standard operation conditions of most optoelectronic devices and is potentially compatible with thermal vacuum deposition of polycrystalline thin films.

Colloidal quantum dots (QDs) show great promise as LED phosphors due to their tunable narrow-band emission and ability to produce high-quality white light. Currently, the most suitable QDs for lighting applications are based on cadmium, which presents a toxicity problem for consumer applications. The most promising cadmium-free candidate QDs are based on InP, but their quality lags much behind that of cadmium based QDs. This is not only because the synthesis of InP QDs is more challenging than that of Cd-based QDs, but also because the large lattice parameter of InP makes it difficult to grow an epitaxial, defect-free shell on top of such material. Here, we propose a viable approach to overcome this problem by alloying InP nanocrystals with Zn²⁺ ions, which enables the synthesis of In_xZn_yP alloy QDs having lattice constant that can be tuned from 5.93 Å (pure InP QDs) down to 5.39 Å by simply varying the concentration of the Zn precursor. This lattice engineering allows for subsequent strain-free, epitaxial growth of a ZnSe_zS_1-z shell with lattice parameters matching that of the core. We demonstrate, for a wide range of core and shell compositions (i.e.; varying x, y, and z), that the photoluminescence quantum yield is maximal (up to 60%) when lattice mismatch is minimal.