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The commercial viability of fluorescent materials is critically contingent on their thermal stability. Recent interest has converged on lead-free double perovskites (DPs), renowned for their optical properties mirroring those of traditional lead-based counterparts and superior atmospheric stability. However, these materials encounter significant fluorescence degradation in thermal environments, a challenging scenario given the high temperatures endemic to the surfaces of optoelectronic devices during prolonged operation, detrimentally impacting the fluorescent attributes of lead-free DPs. To address this challenge, in situ synthesis of lead-free DP nanocrystals (NCs) within KIT-6 mesoporous molecular sieves is proposed, yielding Cs2AgIn0.98Bi0.02Cl6@KIT-6 NCs with enhanced optical qualities. Experimental results demonstrate a marked enhancement in the fluorescence thermal stability of these NCs, attributed to the protective KIT-6 shell layer. Subjected to high power operation (100 mA) for 270 minutes, the fabricated orange light-emitting diode (LED) device maintained 80% of initial luminous efficiency, despite the resultant elevated surface temperature of 326.8 K. Therefore, this novel in situ assembly approach significantly bolsters the operational stability of lead-free DPs, paving the way for their potential commercial applications. [ABSTRACT FROM AUTHOR]

Pb‐free double‐perovskite (DP) scintillators are highly promising candidates for X‐ray imaging because of their superior optoelectronic properties, low toxicity, and high stability. However, practical applications require Pb‐free DP crystals to be ground and mixed with polymers to produce scintillator films. Grinding can compromise film uniformity and optical properties, thereby affecting imaging resolution. In this study, an in situ fabrication strategy is proposed to facilitate the crystalline growth of Pb‐free Cs2AgInxBi1‐xCl6 micron sheets in polymethyl methacrylate in a single step. By adjusting the In3+/Bi3+ ratio, Cs2AgIn0.9Bi0.1Cl6/PMMA composite films (CFs) with excellent scintillation properties are obtained, including a light yield of up to 32000 photons per MeV and an X‐ray detection limit of 87 nGyairs−1. This strategy also enabled the production of large Cs2AgIn0.9Bi0.1Cl6/PMMA CFs, which demonstrated favorable flexibility and stability, fabricating products with advanced eligibility for commercial applications. The CFs exhibited outstanding performances in X‐ray imaging, producing high‐resolution structures and providing a new avenue for the development of Pb‐free DP materials in fields such as medical imaging and safety detection. [ABSTRACT FROM AUTHOR]

All inorganic perovskite nanocrystals (NCs) have emerged as versatile materials for gas sensing due to their tunable optical properties and high surface-to-volume ratios. However, CsPbCl3 has limitations when it comes to gas sensing. In this study, we explore the potential of Mn2+-doped CsPbCl3 NCs as a room-temperature sensing platform for ammonia (NH3) gas detection. By incorporating Mn2+ dopants into the CsPbCl3 lattice, we enhance the sensitivity of the NCs to NH3 gas. Additionally, NH3 molecules interact with the NCs, leading to the dynamic passivation of Cl– vacancies. We systematically investigate the sensing performance of Mn:CsPbCl3 NCs by using varying NH3 concentrations, different exposure conditions, and exposure cycles, revealing a reversible and concentration-dependent response. The sensor based on Mn2+-doped CsPbCl3 NCs has good selectivity for NH3 at room temperature, showing a higher sensitivity (2.12 at 100 ppm) than the pure CsPbCl3 NC sensor (1.10 at 100 ppm), and good repeatability. The unique optical properties of Mn:CsPbCl3 NCs, coupled with their responsiveness to NH3, make them promising candidates for developing efficient and cost-effective room-temperature NH3 gas sensors. This work contributes to the advancement of NC-based gas sensing technologies and highlights the potential of Mn-doped CsPbCl3 NCs in environmental monitoring, industrial safety, and other gas sensing applications. [ABSTRACT FROM AUTHOR]

Perovskite nanocrystals (PeNCs) have emerged as a promising class of luminescent materials offering size and composition-tunable luminescence with high efficiency and color purity in the visible range. PeNCs doped with Yb3+ ions, known for their near-infrared (NIR) emission properties, have gained significant attention due to their potential applications. However, these materials still face challenges with weak NIR electroluminescence (EL) emission and low external quantum efficiency (EQE), primarily due to undesired resonance energy transfer (RET) occurring between the host and Yb3+ ions, which adversely affects their emission efficiency and device performance. Herein, we report the synergistic enhancement of NIR emission in a CsPbCl3 host through co-doping with Yb3+/Nd3+ ions for perovskite LEDs (PeLEDs). The co-doping of Yb3+/Nd3+ ions in a CsPbCl3 host resulted in enhanced NIR emission above 1000 nm, which is highly desirable for NIR optoelectronic applications. This cooperative energy transfer between Yb3+ and Nd3+ can enhance the overall efficiency of energy conversion. Furthermore, the PeLEDs incorporating the co-doped CsPbCl3/Yb3+/Nd3+ PeNCs as an emitting layer exhibited significantly enhanced NIR EL compared to the single doped PeLEDs. The optimized co-doped PeLEDs showed improved device performance, including increased EQE of 6.2% at 1035 nm wavelength and low turn-on voltage. Our findings highlight the potential of co-doping with Yb3+ and Nd3+ ions as a strategy for achieving synergistic enhancement of NIR emission in CsPbCl3 perovskite materials, which could pave the way for the development of highly efficient perovskite LEDs for NIR optoelectronic applications. [ABSTRACT FROM AUTHOR]