Stabilization of Lead-Reduced Metal Halide Perovskite Nanocrystals by High-Entropy Alloying.

Colloidal metal halide perovskite (MHP) nanocrystals (NCs) are an emerging class of fluorescent quantum dots (QDs) for next-generation optoelectronics. A great hurdle hindering practical applications, however, is their high lead content, where most attempts addressing the challenge in the literature compromised the material's optical performance or colloidal stability. Here, we present a postsynthetic approach that stabilizes the lead-reduced MHP NCs through high-entropy alloying. Upon doping the NCs with multiple elements in considerably high concentrations, the resulting high-entropy perovskite (HEP) NCs remain to possess excellent colloidal stability and narrowband emission, with even higher photoluminescence (PL) quantum yields, ηPL, and shorter fluorescence lifetimes, τPL. The formation of multiple phases containing mixed interstitial and doping phases is suggested by X-ray crystallography. Importantly, the crystalline phases with higher degrees of lattice expansion and lattice contraction can be stabilized upon high-entropy alloying. We show that the lead content can be approximately reduced by up to 55% upon high-entropy alloying. The findings reported here make one big step closer to the commercialization of perovskite NCs.

Reversible Dihydrogen Activation and Hydride Transfer by a Uranium Nitride Complex.

Cleavage of dihydrogen is an important step in the industrial and enzymatic transformation of N2 into ammonia. The reversible cleavage of dihydrogen was achieved under mild conditions (room temperature and 1 atmosphere of H2 ) by the molecular uranium nitride complex, [Cs{U(OSi(Ot Bu)3 )3 }2 (µ-N)] 1, leading to a rare hydride-imide bridged diuranium(IV) complex, [Cs{U(OSi(Ot Bu)3 )3 }2 (µ-H)(µ-NH)], 2 that slowly releases H2 under vacuum. This complex is highly reactive and quickly transfers hydride to acetonitrile and carbon dioxide at room temperature, affording the ketimide- and formate-bridged UIV species [Cs{U(OSi(Ot Bu)3 )3 }2 (µ-NH)(µ-CH3 CHN)], 3 and [Cs{U(OSi(Ot Bu)3 )3 }2 (µ-HCOO)(µ-NHCOO)], 4.