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1. Efficient and Stable Blue Light Emitting Diodes Based on CsPbBr ₃ Nanoplatelets with Surface Passivation by a Multifunctional Organic Sulfate

   https://doi.org/10.1002/aenm.202201605  

   Liu, He; Worku, Michael; Mondal, Animesh; Shonde, Tunde_Blessed; Chaaban, Maya; Ben‐Akacha, Azza; Lee, Sujin; Gonzalez, Fabiola; Olasupo, Oluwadara; Lin, Xinsong; et al (July 2022, Advanced Energy Materials)

   Abstract Metal halide perovskite nanocrystals (NCs) have emerged as highly promising light emitting materials for various applications, ranging from perovskite light‐emitting diodes (PeLEDs) to lasers and radiation detectors. While remarkable progress has been achieved in highly efficient and stable green, red, and infrared perovskite NCs, obtaining efficient and stable blue‐emitting perovskite NCs remains a great challenge. Here, a facile synthetic approach for the preparation of blue emitting CsPbBr₃nanoplatelets (NPLs) with treatment by an organic sulfate is reported, 2,2‐(ethylenedioxy) bis(ethylammonium) sulfate (EDBESO₄), which exhibit remarkably enhanced photoluminescence quantum efficiency (PLQE) and stability as compared to pristine CsPbBr₃NPLs coated with oleylamines. The PLQE is improved from ≈28% for pristine CsPbBr₃NPLs to 85% for EDBESO₄treated CsPbBr₃NPLs. Detailed structural characterizations reveal that EDBESO₄treatment leads to surface passivation of CsPbBr₃NPLs by both EDBE²⁺and SO₄^2–ions, which helps to prevent the coalescence of NPLs and suppress the degradation of NPLs. A simple proof‐of‐concept device with emission peaked at 462 nm exhibits an external quantum efficiency of 1.77% with a luminance of 691 cd m⁻²and a half‐lifetime of 20 min, which represents one of the brightest pure blue PeLEDs based on NPLs reported to date. 

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2. Simultaneous Synthesis, Modification, and DFT Calculation of Three‐Color Lead Halide Perovskite Phosphors for Improving Stability and Luminous Efficiency of WLEDs

   https://doi.org/10.1002/adom.202101765  

   Sun, Yao; Li, Yini; Zhang, Wanying; Zhu, Peifen; Zhu, Hongyang; Qin, Weiping; Wang, Guofeng (November 2021, Advanced Optical Materials)

   Abstract The all‐inorganic metal halide perovskite CsPbX₃(X = Cl, Br, and I) has received extensive attention in the field of white light‐emitting diodes (WLEDs) due to its high luminous intensity and high color purity. However, the shortcoming of poor stability directly affects the luminous performance of the WLED devices and reduces their luminous efficiency, which has become an urgent problem to be solved. Here, three‐color lead halide perovskite phosphors (blue‐emitting CsPbBr₃synthesized at 20 °C (CPB‐20), green‐emitting CsPbBr₃‐80 (CPB‐80)/CsPbBr₃:SCN⁻(CPB:SCN⁻), and red‐emitting PEA₂PbBr₄(PPB)/PEA₂PbBr₄:Mn²⁺(PPB:Mn²⁺)) with higher stability and luminous intensity are simultaneously prepared and applied in WLEDs. Density functional theory is used to optimize the structures of CsPbBr₃and PEA₂PbBr₄, and to calculate the work function, optical properties, and charge density difference. Not only the WLED devices with three‐color lead halide perovskite phosphors are constructed, but also WLED devices from warm white to cold white are realized by tuning the ratio of the different emissions, and a superior color quality (color rendering index of 96) and ideal correlated color temperature (CCT of 9376 K) are achieved. This work will set the stage for exploring low‐cost, environmentally friendly, high‐performance WLEDs. 

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3. Eco-friendly synthesis and stability analysis of CsPbBr ₃ and poly(methyl methacrylate)-CsPbBr ₃ films

   https://doi.org/10.1088/1361-6528/adbbf6  

   Huang, You-Lin; Li, Wei; Yang, Fuqian (March 2025, Nanotechnology)

   Abstract This study presents an eco-friendly mechanochemical synthesis of cesium lead bromide (CsPbBr₃), eliminating the need of organic solvents and high temperatures. The synthesized CsPbBr₃powder is used to fabricate poly(methyl methacrylate) (PMMA)-CsPbBr₃films and CsPbBr₃nanocrystals (NCs). The photoluminescence (PL) peaks of the emission light are centered at 541 nm, 538 nm, and 514 nm for the CsPbBr₃powder, PMMA-CsPbBr₃films, and CsPbBr₃NCs, respectively, correlating with crystal sizes of 0.96, 0.56, and 0.12μm, respectively. The PL lifetime analysis reveals decay times ( ${\tau }_1,{\tau }_2$) of (4.18, 20.08), (5.7, 46.99), and (5.81, 23.14) in the units (ns, ns) for the CsPbBr₃powder, PMMA-CsPbBr₃films, and CsPbBr₃NCs, respectively. The PL quantum yield of the CsPbBr₃NCs in toluene is 61.3%. Thermal activation energies for thermal quenching are 217.48 meV (films) and 178.15 meV (powder), indicating improved thermal stability with the PMMA encapsulation. The analysis of the PL intensity decay from water diffusion in the PMMA-CsPbBr₃films yields 1.70 × 10⁻¹²m²s⁻¹for the diffusion coefficient of water, comparable to that for water diffusion in pure PMMA. This work demonstrates a scalable, sustainable strategy for CsPbBr₃synthesis and stability enhancement for optoelectronic applications. 

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4. Divalent Anionic Doping in Perovskite Solar Cells for Enhanced Chemical Stability

   https://doi.org/10.1002/adma.201800973  

   Gong, Jue; Yang, Mengjin; Rebollar, Dominic; Rucinski, Jordan; Liveris, Zachary; Zhu, Kai; Xu, Tao (July 2018, Advanced Materials)

   Abstract The chemical stabilities of hybrid perovskite materials demand further improvement toward long‐term and large‐scale photovoltaic applications. Herein, the enhanced chemical stability of CH₃NH₃PbI₃is reported by doping the divalent anion Se²⁻in the form of PbSe in precursor solutions to enhance the hydrogen‐bonding‐like interactions between the organic cations and the inorganic framework. As a result, in 100% humidity at 40 °C, the 10% w/w PbSe‐doped CH₃NH₃PbI₃films exhibited >140‐fold stability improvement over pristine CH₃NH₃PbI₃films. As the PbSe‐doped CH₃NH₃PbI₃films maintained the perovskite structure, a top efficiency of 10.4% with 70% retention after 700 h aging in ambient air is achieved with an unencapsulated 10% w/w PbSe:MAPbI₃‐based cell. As a bonus, the incorporated Se²⁻also effectively suppresses iodine diffusion, leading to enhanced chemical stability of the silver electrodes. 

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5. Pure Blue Electroluminescence by Differentiated Ion Motion in a Single Layer Perovskite Device

   https://doi.org/10.1002/adfm.202102006  

   Mishra, Aditya; Alahbakhshi, Masoud; Haroldson, Ross; Gu, Qing; Zakhidov, Anvar_A; Slinker, Jason_D (June 2021, Advanced Functional Materials)

   Abstract Blue electroluminescence is highly desired for emerging light‐emitting devices for display applications and optoelectronics in general. However, saturated, efficient, and stable blue emission has been challenging to achieve, particularly in mixed‐halide perovskites, where intrinsic ion motion and halide segregation compromises spectral purity. Here, CsPbBr_3−xCl_xperovskites, polyelectrolytes, and a salt additive are leveraged to demonstrate pure blue emission from single‐layer light‐emitting electrochemical cells (LECs). The electrolytes transport the ions from salt additives, enhancing charge injection and stabilizing the inherent perovskite emissive lattice for highly pure and sustained blue emission. Substituting Cl into CsPbBr₃tunes the perovskite luminescence from green through blue. Sky blue and saturated blue devices produce International Commission on Illumination coordinates of (0.105, 0.129) and (0.136, 0.068), respectively, with the latter meeting the US National Television Committee standard for the blue primary. Likewise, maximum luminances of 2900 and 1000 cd m⁻², external quantum efficiencies (EQEs) of 4.3% and 3.9%, and luminance half‐lives of 5.7 and 4.9 h are obtained for sky blue and saturated blue devices, respectively. Polymer and LiPF₆inclusion increases photoluminescence efficiency, suppresses halide segregation, induces thin‐film smoothness and uniformity, and reduces crystallite size. Overall, these devices show superior performance among blue perovskite light‐emitting diodes (PeLEDs) and general LECs. 

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