Strong quantum confinement in Mn-doped semiconductor nanocrystals enhances dopant–carrier exchange interactions. Here, we report the synthesis and optical properties of strongly quantum confined, quasi two-dimensional, Mn-doped CsPbCl3 nanoplatelets. A room-temperature synthesis was employed to prepare the platelets with thickness 2.2 nm (4 monolayers), which is significantly smaller than the Bohr excitonic diameter of CsPbCl3 (5 nm). Efficient transfer of excitonic energy from the host to the Mn2+ dopant ions leads to a spin-forbidden 4T1–6A1 Mn d-electron emission with the highest quantum yield of ∼20% and exhibits a long lifetime of 1.6 ms. Subsequent anion exchange reactions at room temperature lead to the formation of Mn-doped CsPbBr3 nanoplatelets, with weak Mn emission. These newly developed Mn-doped cesium lead halide nanoplatelets are suitable candidates for exploring the effects of quantum confinement on dopant–carrier exchange interaction and exhibiting interesting magneto-optic properties.

Lead bromide (PbBr 2 ,99.999%), lead iodide (PbI 2 , 99.999%), lead chloride (PbCl 2 , 98%), manganese (II) bromide (MnBr 2 , 98%), ytterbium (III) nitrate pentahydrate {Yb(NO 3) 3 .5H 2 O, 99.99%}, caesium carbonate (Cs 2 CO 3 , 99.9%), oleic acid (OA, 90%), 1-octadecene (ODE, 90%), oleylamine (OLA, 98%), trioctylphosphine (TOP, 90%), methyl acetate (MeOAc, 99.5%), N,N-dimethylformamide (DMF, 99.8%), hydrogen bromide (HBr, 43 wt%, 99.99%) were purchased from Aldrich and were used without further purification. Acetone (99.0%, SDFCL), Hexane (99.99%, Rankem), Toluene (99.5%, Rankem) solvents are used as obtained.

Metal chalcogenide perovskites were proposed as potential solar cell material in 2015. The theoretical maximum solar cell efficiencies of some chalcogenide perovskites are ∼30%, similar to CH 3 NH 3 PbI 3 perovskites. The foreseen advantages of chalcogenide perovskites are high thermal and aqueous stability along with nontoxic elemental composition. To date, a reasonable amount of computational and experimental work has been reported on the synthesis, electronic and optical properties of chalcogenide perovskites. Major experimentally studied compounds are AZrS 3 (A = Ba and Sr), Ba 3 Zr 2 S 7 , and LaYS 3 , which have direct band gaps in the range 1.3 to 2 eV, along with strong light absorption coefficients and small effective masses of charge carriers. There are a few more compositions with similar properties that have been suggested by computational screening. In this perspective, we summarize both the computational and experimental progresses made in designing chalcogenide perovskites for optoelectronic properties. Then we discuss the material design challenges that need to be addressed in the coming years for successful solar cell application.

Inorganic metal halide perovskite nanocrystals (NCs) are promising materials for emission-based applications; however, the inclusion of toxic lead may limit their commercial viability. This paper describes two cesium cupriferous iodides as nontoxic alternatives to lead containing perovskites. These nanocrystals were synthesized with tailored composition and morphology by a hot-injection colloidal route to produce hexagonal nanoplates (NPs) of blue-emitting Cs3Cu2I5 and nanorods (NRs) of yellow-emitting CsCu2I3. Phase purity was confirmed by Rietveld refinement of X-ray powder diffraction patterns and solid state 133Cs MAS NMR with both compounds exhibiting high thermal stability suitable for optoelectronic technologies. Phase mixing allows linear tuning of Commission Internationale de l’Eclairage (CIE) coordinates from (0.145, 0.055) to (0.418, 0.541) such that a 1:8 molar ratio of Cs3Cu2I5 NPs and CsCu2I3 NRs yields white emission, while the 133Cs MAS NMR demonstrates that these photophysical effects are not attributed to any changes in the Cu oxidation state.

Physical Unclonable Functions (PUFs) address the inherent limitations of conventional hardware security solutions in edge-computing devices. Despite impressive demonstrations with silicon circuits and crossbars of oxide memristors, realizing efficient roots of trust for resource-constrained hardware remains a significant challenge. Hybrid organic electronic materials with a rich reservoir of exotic switching physics offer an attractive, inexpensive alternative to design efficient cryptographic hardware, but have not been investigated till date. Here, we report a breakthrough security primitive exploiting the switching physics of one dimensional halide perovskite memristors as excellent sources of entropy for secure key generation and device authentication. Measurements of a prototypical 1 kb propyl pyridinium lead iodide (PrPyr[PbI3]) weak memristor PUF with a differential write-back strategy reveals near ideal uniformity, uniqueness and reliability without additional area and power overheads. Cycle-to-cycle write variability enables reconfigurability, while in-memory computing empowers a strong recurrent PUF construction to thwart machine learning attacks.