All-Inorganic Manganese-Based CsMnCl3 Nanocrystals for X-Ray Imaging.

Lead-based halide perovskite nanomaterials with excellent optical properties have aroused great attention in the fields of solar cells, light-emitting diodes, lasing, X-ray imaging, etc. However, the toxicity of lead prompts researchers to develop alternatives to cut down the usage of lead. Herein, all-inorganic manganese-based perovskite derivatives, CsMnCl3 nanocrystals (NCs), with uniform size and morphology have been synthesized successfully via a modified hot-injection method. These NCs have a direct bandgap of 4.08 eV and a broadband emission centered at 660 nm. Through introducing modicum lead (1%) into the CsMnCl3 NCs, the photoluminescence intensity greatly improves, and the quantum yield (PLQY) increases from 0.7% to 21%. Furthermore, the CsMnCl3 :1%Pb NCs feature high-efficiency of X-ray absorption and radioluminescence, which make these NCs promising candidates for X-ray imaging.

Push-pull electron effects of the complexant in a Li atom doped molecule with electride character: a new strategy to enhance the first hyperpolarizability.

Differing from the reported strategy of push or pull electron effects of the complexant, a new strategy of the combination effects of both push and pull electrons of the complexant to enhance the first hyperpolarizability is performed with two Li atom doped complexants with a pair of difluorophenyl subunit rings. Large variance of the static first hyperpolarizabilities (beta(0)) are exhibited at the MP2/6-311++G(d,p) level. The order of the beta(0) values is 2.9 x10(2) (complexant UD) << 5.9 x 10(3) (LL) < 1.9 x 10(4) (H-L) < 2.3 x 10(4) (H(F)-L) < 3.2 x 10(4) (L-L) < 7.8 x 10(5) a.u. (H(F)-L(F)). It is found that H(F)-L(F) with the edge-type push-pull electronic effect of the complexant has the largest beta(0). The edge-type push-pull electronic effect brings a 2700 times increase in the beta(0) from the UD to H(F)-L(F) structure. It shows that the push-pull electronic effect is a highly effective strategy to enhance the beta(0) value. The beta(0) (7.8 x 10(5) a.u.) of the H(F)-L(F) is considerable, due to the small DeltaE and the very large Delta mu (18.085 a.u.), which comes from the corresponding long-range charge transfer transition. It is interesting that a pair of subunit rings of the complexant may have different electronic effects. In H-L and H(F)-L(F), the left ring with a longer distance between Li and the subunit ring exhibits a push electronic effect, while the right ring with the shorter distance exhibits a pull electronic effect. This work may contribute to the development of potential high-performance nonlinear optical materials.