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Abstract BackgroundResearch into perovskite nanocrystals (PNCs) has uncovered interesting properties compared to their bulk counterparts, including tunable optical properties due to size‐dependent quantum confinement effect (QCE). More recently, smaller PNCs with even stronger QCE have been discovered, such as perovskite magic sized clusters (PMSCs) and ligand passivated PbX₂metal halide molecular clusters (MHMCs) analogous to perovskites. ObjectiveThis review aims to present recent data comparing and contrasting the optical and structural properties of PQDs, PMSCs, and MHMCs, where CsPbBr₃PQDs have first excitonic absorption around 520 nm, the corresponding PMSCS have absorption around 420 nm, and ligand passivated MHMCs absorb around 400 nm. ResultsCompared to normal perovskite quantum dots (PQDs), these clusters exhibit both a much bluer optical absorption and emission and larger surface‐to‐volume (S/V) ratio. Due to their larger S/V ratio, the clusters tend to have more surface defects that require more effective passivation for stability. ConclusionRecent study of novel clusters has led to better understanding of their properties. The sharper optical bands of clusters indicate relatively narrow or single size distribution, which, in conjunction with their blue absorption and emission, makes them potentially attractive for applications in fields such as blue single photon emission. 

Mn²⁺doping of CsPbBr₃perovskite magic‐sized clusters (PMSCs) has been reported previously, where PMSCs with first excitonic absorption and photoluminescence (PL) around 425 nm were reported originally, followed by Mn²⁺‐doped PMSCs with host absorption and PL around 400 nm. There, the observed 25 nm blueshift was attributed to smaller PMSCs or the Cl⁻ions introduced by MnCl₂as dopant precursor. However, subsequent studies suggest that the 400 nm band may instead be due to ligand‐assisted metal halide molecular clusters (MHMCs), which lack the A component of perovskite. This raises the question whether the originally claimed Mn²⁺‐doped PMSCs are actually MHMCs. To unambiguously address this issue, Mn²⁺‐doped CH₃NH₃PbBr₃PMSCs were synthesized with PL at both 440 nm, attributed to the PMSC, and at 600 nm, attributed to Mn²⁺. Blueshifting of the host absorption and PL bands due to Cl⁻codoping is avoided by selecting MnBr₂as dopant precursor rather than MnCl₂. Dopant incorporation into PMSCs is further supported by PL excitation, time‐resolved PL, and electron paramagnetic resonance studies. This work provides direct and strong evidence of successful Mn²⁺doping in PMSCs. 

In this study, two pairs of 0D chiral copper iodide clusters were synthesized. The structural rigidity is increased by halogen modulation to obtain a near unity PLQY. The applications in white LED and X-ray imaging are extremely promising. 

Ligand‐assisted perovskite nanoclusters (PNCs) have been synthesized using oleylamine and L‐ or D‐cysteine as confirmed based on their characteristic electronic absorption bands around 430 nm based on ultraviolet‐visible spectra. Circular dichroism (CD) spectra show distinct chiroptical bands in the 430–440 nm region, revealing the chirality of the PNCs. Interestingly, the sign of the CD signal is always negative, independent of the chirality for L‐ or D‐cystine. This 430–440 nm CD band is tentatively attributed to the formation of new chiral stereocenters within the PNCs with an uneven ratio of two enantiomers induced by the asymmetric liquid–liquid interface from the solvent and antisolvent used during synthesis. 

A solid-state synthesis of blue-emitting lead halide nanoclusters has been demonstrated for the first time.