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Organic long‐persistent luminescence (OLPL) based on long‐lived charge‐separated (CS) states shows considerable emission persistence time owing to the ability to store absorbed photon energy. Herein, a novel electron donor‐acceptor (D–A) binary system consisting of electron donor 4,4,4‐tris[3methylphenyl(phenyl)amino]triphenylamine and electron acceptor tris‐[3‐(3‐pyridyl)mesityl]borane is designed and investigated for outstanding OLPL performance. It is found that the proposed binary system exhibits effective OLPL emission that lasted for more than 100 s after 1 min of ultraviolet light irradiation at room temperature (292 K). Moreover, this electron D–A binary system also exhibits thermally activated delayed fluorescence emission prior to OLPL emission. Both emission types are found to be temperature‐sensitive, which are believed to result from the occurrence of reverse intersystem crossing and the formation of a CS state, respectively. The findings enrich the electron D–A system OLPL materials and clarify the rich excited‐state transitions during OLPL emission of electron D–A systems. [ABSTRACT FROM AUTHOR]

Lead‐free halide perovskites and their variants have attracted great attention due to their non‐toxicity and good photophysical properties. Here, a series of undoped and antimony‐doped all‐inorganic, 0D, indium‐based perovskite variant nanocrystals (NCs): (RbxCs1−x)3InCl6 and (RbxCs1−x)3InCl6:Sb (0 ≤ x ≤ 1) NCs, is reported. Among them, Sb‐doped NCs exhibit green emission. Mixing Rb‐Cs NCs show the higher photoluminescence (PL) quantum efficiency (PLQE) and better stability than unalloyed NCs (x = 0 or 1). The effect of crystal size on PL property of (Rb0.75Cs0.25)3InCl6:Sb is analyzed in detail. More interestingly, In‐based perovskite variant NCs containing coordinated water are successfully synthesized by a two‐step method (variable temperature hot injection and saturated steam post treatment). The best PLQE of Sb‐doped Cs2InCl5(H2O) NCs reaches 95.5%, which is a new PLQE record for yellow emissive lead‐free perovskite and variant NCs. In addition, the emission mechanism is further clarified by temperature‐dependent PL and femtosecond transient absorption techniques. [ABSTRACT FROM AUTHOR]

As the increasing demand of lighting display technology, environmentally‐friendly, economic light‐emitting materials with high performance are required. Herein, a novel solution‐processed, highly emissive copper chloride compound β‐Cs3Cu2Cl5 is reported. The crystal structure determined by the Rietveld refinement of the powder X‐ray diffraction patterns shows that the corner‐sharing tetrahedral Cu–Cl chains are surrounded by Cs+ cations, yielding a one‐dimensional structure at molecular level. The all‐inorganic compound shows excellent photostability, and is thermally stable up to 550 °C. Excitingly, it exhibits room‐temperature photoluminescence in the green region with near‐unity quantum yield. Currently, this appears to be the most efficient lead‐free all‐inorganic green‐light emitting metal halides reported. This work presents a new direction toward the design of high‐efficiency, economic, and environmentally‐friendly light‐emitting materials. [ABSTRACT FROM AUTHOR]

Low‐dimensional metal halides have recently attracted extensive attention owing to their unique structure and photoelectric properties. Herein, we report the colloidal synthesis of all‐inorganic low‐dimensional cesium copper halide nanocrystals (NCs) by adopting a hot‐injection approach. Using the same reactants and ligands, but different reaction temperatures, both 1D CsCu2I3 nanorods and 0D Cs3Cu2I5 NCs can be prepared. Density functional theory indicates that the reduced dimensionality in 1D CsCu2I3 compared to 0D Cs3Cu2I5 makes the excitons more localized, which accounts for the strong emission of 0D Cs3Cu2I5 NCs. Subsequent optical characterization reveals that the highly luminescent, strongly Stokes‐shifted broadband emission of 0D Cs3Cu2I5 NCs arises from the self‐trapped excitons. Our findings not only present a method to control the synthesis of low‐dimensional cesium copper halide nanocrystals but also highlight the potential of 0D Cs3Cu2I5 NCs in optoelectronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • (NEA) 2 PbBr 4 and (NEA) 2 PbBr 3 I 1 nanosheets is quenching by triplet energy transfer. • (NEA) 2 PbBr 4− x I x (x = 2,3,4) is not quenching by triplet energy transfer. • After the triplet energy transfer, triplet excimer will be generated in (NEA) 2 PbBr 4. • Triplet excimer will not be generated in (PEA) 0.8 (NEA) 0.2) 2 PbBr 4 nanosheets. A series of two-dimensional hybrid perovskite nanosheets containing organic triplet energy acceptor, (NEA) 2 PbBr 4− x I x (NEA = C 12 H 11 NH 3), were synthesized. Steady-state and transient spectra show that nanosheets with the appropriate energy level, the intramolecular triplet energy transfer will occur across the inorganic/organic interface. The first step of triplet energy transfer is the transfer of holes from inorganic part to organic part, and the rate is 1.55 × 10 12 s - 1 in (NEA) 2 PbBr 4 nanosheets. Then the electron transfer with rate of 5.5 × 10 10 s - 1 takes place to complete the triplet energy transfer process. [ABSTRACT FROM AUTHOR]