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Despite rapid progress and wide applications of room temperature phosphorescence (RTP) materials, it is still a great challenge to optimize the RTP activity through rational structural design at a molecular level. Herein, a successful cationic engineering strategy is demonstrated to modulate the crystal flexibility achieving controllable RTP in a new pair of metal halides [APML]ZnCl4 ([APML] = N‐(3‐Aminopropyl)morpholine) and [AEML]ZnCl4 ([AEML] = N‐(2‐Aminoethyl)morpholine). Both halides display blue fluorescence under 365 nm UV. Comparing with longer [APML]+, shorter [AEML]+ significantly enhances crystal rigidity and restrains non‐radiative scattering, boosting photoluminescence quantum yield (PLQY) from 18.89% to 22.41%. Synchronously, enhanced crystal rigidity significantly promotes the inter‐system crossing from singlet to triplet excited states. As a consequence, [AEML]ZnCl4 displays long‐lived green RTP property with millisecond scale lifetime in contrast to the blank RTP activity of [APML]ZnCl4. Comprehensive investigations demonstrate that the energy transfer between inorganic and organic components greatly changes the redistribution of singlet and triplet excited states, resulting in distinct phosphorescence activity. The different short‐lived blue fluorescence and long‐lived green phosphorescence provide a color‐time‐dual‐resolved luminescent tag with advanced applications in anti‐counterfeiting, etc. This work highlights a new structural engineering strategy to achieve controllable RTP affording a guide to rationally design RTP materials. [ABSTRACT FROM AUTHOR]

Although the luminescent performance of organic–inorganic metal halides (OIMHs) have obtained significant advances, achieving intrinsic water‐stable OIMHs remain a substantial challenge due to the fragile ionic nature of hybrid the halide structure. To overcome these challenges, a structural design strategy is proposed that involves the use of highly hydrophobic cations as a protective layer to improve the water stability of OIMH. Herein, an aprotic trimethylsulfoxonium [TMSO]+ is selected as a hydrophobic cation and successfully assemble two new manganese based OIMHs of (TMSO)MnCl3 and (TMSO)MnBr3 through facile solid and liquid phase reaction methods. Remarkably, these halides exhibit strong red light emissions with high quantum yields recorded at 86.1% and 53.4%, respectively, originating from the octahedral [MnX6]4− based one‐dimensional (1D) [MnX3]− chain. Most significantly, these halides present extraordinary structural and luminescent stabilities toward continuous corrosion by humid air, water, and acid‐aqueous solution for more than one month, suggesting promising application prospects in extreme chemical environments. In‐depth Hirshfeld surface calculations demonstrate that the ultrahigh water‐stability benefits from the abundant hydrogen bonds and strong electrostatic interactions between [TMSO]+ and [MnX3]− ions, which provides an underlying insight into the stability mechanism. This water‐stability enhancement strategy represents a breakthrough structural engineering to rationally design more water‐stable OIMH. [ABSTRACT FROM AUTHOR]

Considering the instability and toxicity of 3D Pb-based perovskite nanocrystals, lead-free low-dimensional organic–inorganic hybrid metal halides have attracted widespread attention as potential substitutes. Herein, two new tin-based 0D halides [H4BAPP]SnBr5·Br and [H4BAPP]SnCl5·Cl·H2O (BAPP = 1,4-bis(3-aminopropyl)piperazine) were synthesized successfully based on [SnX5]3− as an emission center. Typically, [H4BAPP]SnBr5·Br and [H4BAPP]SnCl5·Cl·H2O display broadband yellow and yellow-green light emissions originating from the radiative recombination of self-trapped excitons (STEs). The photoluminescence quantum yields (PLQYs) of the two compounds were calculated to be 19.27% and 2.36%, respectively. Furthermore, the excellent chemical and thermal stability and broadband light emissions reveal their potential application in solid-state white lighting diodes. [ABSTRACT FROM AUTHOR]

Environmentally friendly and highly efficient blue luminescent materials are an unremitting pursuit in the optoelectronic field. Herein, we assembled a new 0D lead-free metal halide of (F-PPA)ZnBr4, which exhibits narrow blue light emission with a remarkable PLQY of 50.15%, high stability and high detection sensitivity toward UV light. These results indicate the potential for the application of low-dimensional zinc-based halides in multiple optoelectronic devices. [ABSTRACT FROM AUTHOR]