Silica-Coated Mn-Doped CsPb(Cl/Br)₃ Inorganic Perovskite Quantum Dots: Exciton-to-Mn Energy Transfer and Blue-Excitable Solid-State Lighting

Tunability of emitting colors of perovskite quantum dots (PQDs) was generally realized via composition/size modulation. Due to their bandgap absorption and ionic crystal features, the mixing of multiple PQDs inevitably suffers from reabsorption and anion-exchange effects. Herein, we address these issues with high-content Mn²⁺-doped CsPbCl₃ PQDs that can yield blue-excitable orange Mn²⁺ emission benefited from exciton-to-Mn energy transfer and Cl-to-Br anion exchange. Silica-coating was applied to improve air stability of PQDs, suppress the loss of Mn²⁺, and avoid anion-exchange between different PQDs. As a direct benefit of intense multicolor emissions from Mn²⁺-doped PQD@SiO₂ solid phosphors, a prototype white light-emitting diode with excellent optical performance and superior light stability was constructed using green CsPbBr₃@SiO₂ and orange Mn: CsPb­(Cl/Br)₃@SiO₂ composites as color converters, verifying their potential applications in the field of optoelectronics

Full-Spectral Fine-Tuning Visible Emissions from Cation Hybrid Cs_1–<i>m</i>FA<i>_m</i>PbX₃ (X = Cl, Br, and I, 0 ≤ <i>m</i> ≤ 1) Quantum Dots

Full-color visible emissions are particularly crucial for applications in displays and lightings. In this work, we developed a facile room-temperature ligand-assisted supersaturated recrystallization synthesis of monodisperse, cubic structure Cs_1–<i>m</i>FA<i>_m</i>PbX₃ (X = Cl, Br, and I or their mixtures Cl/Br and Br/I, 0 ≤ <i>m</i> ≤ 1) hybrid perovskite quantum dots (QDs). Impressively, cation substitution of Cs⁺ by FA⁺ was beneficial in finely tuning the band gap and in exciton recombination kinetics, improving the structural stability, and raising the absolute quantum yields up to 85%. With further assistance of anion replacement, full-spectral visible emissions in the wavelength range of 450–750 nm; narrow full width at half-maxima, and a wide color gamut, encompassing 130% of National Television System Committee television color standard, were achieved. Finally, Cs_1–<i>m</i>FA<i>_m</i>PbX₃-polymer films retaining multicolor luminescence are prepared and a prototype white light-emitting diode device was constructed using green Cs_0.1FA_0.9PbBr₃ and red Cs_0.1FA_0.9Br_1.5I_1.5 QDs as color converters, certainly suggesting their potential applications in the optoelectronics field

Excitation-Independent Dual-Color Carbon Dots: Surface-State Controlling and Solid-State Lighting

Long-wavelength orange-red emissions of carbon dots have recently attracted great attention due to their wide applications. Although it is possible to achieve long-wavelength luminescence by varying the incident excitation wavelength, excitation-independency is highly desired in terms of both practical applications and understanding emission mechanisms. In the present work, carbon dots with excitation wavelength independent orange and blue dual-color emissions were synthesized by a facile solvothermal route using <i>p</i>-phenylenediamine as carbon source and formamide as solvent. Structural and spectroscopic characterizations indicated that N- and O-related surface-state controlling via modifying reacting temperature/time was responsible for the dual-color emissions of carbon dots. Moreover, carbon solid film, retaining original orange emissions, was fabricated to explore its possible application as color converter in solid-state lighting. Impressively, by combining orange carbon film and yellow phosphor-in-glass with an InGaN blue chip, light-emitting diode devices with improved color-rendering index and correlated color temperature were successfully constructed

Promoting Charge Separation in <i>g</i>‑C₃N₄/Graphene/MoS₂ Photocatalysts by Two-Dimensional Nanojunction for Enhanced Photocatalytic H₂ Production

Graphitic carbon nitride (<i>g</i>-C₃N₄) is a promising photocatalyst for solar H₂ generation, but the practical application of <i>g</i>-C₃N₄ is still limited by the low separation efficiency of photogenerated charge carriers. Herein, we report the construction of ternary <i>g</i>-C₃N₄/graphene/MoS₂ two-dimensional nanojunction photocatalysts for enhanced visible light photocatalytic H₂ production from water. As demonstrated by photoluminescence and transient photocurrent studies, the intimate two-dimensional nanojuction can efficiently accelerate the charge transfer, resulting in the high photocatalytic activity. The <i>g</i>-C₃N₄/graphene/MoS₂ composite with 0.5% graphene and 1.2% MoS₂ achieves a high H₂ evolution rate of 317 μmol h^–1 g^–1, and the apparent quantum yield reaches 3.4% at 420 nm. More importantly, the ternary <i>g</i>-C₃N₄/graphene/MoS₂ two-dimensional nanojunction photocatalyst exhibits much higher photocatalytic activity than the optimized Pt-loaded <i>g</i>-C₃N₄ photocatalyst