Quasi-2D perovskites, composed of self-organized quantum well structures, are emerging as gain materials for laser applications. Here we investigate the influence of domain distribution on the laser emission of CsPbCl 1.5 Br 1.5 -based quasi-2D perovskites. The use of 2,2-diphenylethylammonium bromide (DPEABr) as a ligand enables the formation of quasi-2D film with a large-n-dominated narrow domain distribution. Due to the reduced content of small-n domains, the incomplete energy transfer from small-n to large-n domains can be greatly addressed. Moreover, the photoinduced carriers can be concentrated on most of the large-n domains to reduce the local carrier density, thereby suppressing the Auger recombination. By controlling the domain distribution, we achieve blue amplified spontaneous emission and single-mode vertical-cavity surfaceemitting lasing with low thresholds of 6.5 and 9.2 μJ cm −2 , respectively. This work provides a guideline to design the domain distribution to realize low-threshold multicolor perovskite lasers.

Exciton behaviors including exciton formation and dissociation dynamics play an essential role in the optoelectronic performance of semiconductive materials but remain unexplored in semiconductive metal–organic frameworks (MOFs). Herein, we reveal that the exciton behaviors in semiconductive MOFs can be regulated by framework–guest interactions, a feature often not achievable in traditional inorganic or organic semiconductors. Incorporation of the electron-deficient molecule within the pores of a terbium-based semiconductive MOF (Tb2L2·4H2O·6DMF, L = TATAB3–, 4,4′,4″-s-triazine-1,3,5-triyltri-p-aminobenzoate, DMF = N,N-dimethylformamide) results in efficient energy transfer from the MOF skeleton to molecular acceptors, with a yield of up to 77.4%. This interaction facilitates distinctive exciton type conversion, giving rise to modified conductivity and photoelectric performance. We further fabricated a MOF-based X-ray detection device to demonstrate how the new architecture bolsters the optoelectronic efficiency, which outperforms the properties of parent semiconductive MOFs, with more than 60 times and 40 times enhancement of the photocurrent on–off ratio and detection sensitivity, respectively. With judiciously optimized exciton behaviors, the detection device exhibits a high sensitivity of 51.9 μC Gyair –1 cm–2 and records a charge carrier mobility-lifetime product of 1.12 × 10–3 cm2 V–1 among MOF-based X-ray detectors, which are competitive with values for commercially available detectors. These findings demonstrate a rational synthetic approach to designing exciton arrangements to improve the optoelectronic efficiency of semiconductive MOFs.

Charge transfer plays an important role in photophysical and photochemical reactions. However, the factors affecting the excited chargetransfer state are unclear. Here, two donor−π−acceptor dyads with an excellent blue fluorescence quantum yield are designed by integrating 1,2-diphenylphenanthroimidazole (PPI) as an electron donor and 1,2,4-triazolopyridine (TP) as an electron acceptor through phenyl (P) bridges. In the solvents dichloromethane (DCM) and dimethyl formamide (DMF), the dynamics of intramolecular charge transfer (ICT) of the two dyads (TP-P-PPI and TP-P-P-PPI) is located at the Marcus normal region, while the dynamics of charge recombination (CR) is situated at the Marcus inverted region. Therefore, TP-P-P-PPI with a long π-chain exhibits a longer lifetime of ICT but a shorter lifetime of CR than TP-P-PPI does with a short π-chain. In contrast, when the two dyads are spin-coated into a film, the dynamics of ICT and CR processes of the two dyads are restored to be positively correlated with the π-chain length because of the inhibition of intramolecular torsion between PPI and TP in the excited state of the film. This work demonstrates a specific approach via the molecular torsion to tune the dynamics of the ICT and CR among donor−π−acceptor systems.

Two positional isomers (regioisomers) through changing the substituted position of perylenetetracarboxylic diimide and benzanthrone moieties were designed and synthesized. These two regioisomers exhibit totally different aggregation behaviors. The meta (bay)-substituted...

Using Mn-doped CsPbCl3 nanocrystals (Mn:CsPbCl3 NCs) to improve perovskite’s properties is becoming an important strategy. Here, we demonstrate a modified supersaturated recrystallization route to synthesize high-quality Mn:CsPbCl3 NCs at room temperature. Unprecedentedly, sulfonate ligands with various concentrations are shown to successfully tune the dual-color emission of Mn:CsPbCl3 NCs. Ultrafast transient absorption studies reveal that the host-to-dopant internal energy-transfer process involves the mediated traps. Interestingly, the dual-color emission is tuned via stabilizing mediated traps with a small amount of ligand (band edge (BE) emission reduces and Mn2+ emission increases), passivating the deep traps with a large amount of ligand (Mn2+ emission increases), and destroying Mn:CsPbCl3 NCs with too much ligand (both BE and Mn2+ emission is quenched). Furthermore, the ligand tuning Mn2+ emission exhibits quenching for Cu2+ with high sensitivity and selectivity. Our work provides a new strategy to tune the optical properties of Mn:CsPbCl3 NCs and presents its potential application in an optical detector.