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Fluorescent carbon dots (CDs) are compelling optical emitters to construct white light‐emitting diodes (WLEDs). However, it remains a challenge to achieve large‐scale and highly efficient single‐component white‐light‐emissive CDs suitable for WLED applications. Herein, a low cost, fast processable, environmentally friendly, and one‐step synthetic approach is developed for the preparation of gram‐scale and highly efficient single‐component white‐light‐emissive carbonized polymer dots (SW‐CPDs). It is revealed that hybrid fluorescence/phosphorescence components cooperatively contribute to the emergence of white light emission. The SW‐CPDs exhibit a record quantum yield (QY) of ≈41% for the white light emission observed in solid‐state CD systems, while the QY of the phosphorescence is ≈23% under ambient conditions. Heavy doping of N and P elements as well as presence of covalently cross‐linked polymer frameworks is suggested to account for the emergence of hybrid fluorescence/phosphorescence, which is supported by the experimental results and theoretical calculations. A WLED is fabricated by applying the SW‐CPDs on an UV‐LED chip, showing favorable white‐light‐emitting characteristics with a high luminous efficacy of 18.7 lm W−1 that is comparable to that of state‐of‐the‐art WLEDs reported before.

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Owing to quantum confinement of optical and electrical transitions within isolated [PbBr 6 ] 4− octahedral units, zero-dimensional perovskite Cs 4 PbBr 6 exhibits appealing molecular-like quantum optoelectronic behavior. Although much effort has been made thus far, the origin of the visible photoluminescence observed in Cs 4 PbBr 6 still remains unclear. In addition, its stimulated emission and potential applications are rarely explored. Here, phase-pure Cs 4 PbBr 6 microcrystals with well-defined morphology are developed via an antisolvent approach and exhibit intense photoluminescence centered at ∼518 nm with a photoluminescence quantum yield of ∼30% and a rather large binding energy of ∼267 meV. Optical spectroscopic and systematic structural analyses consistently suggest that the obtained product is phase-pure Cs 4 PbBr 6 . In particular, optical spectroscopic analyses reveal for the first time the agreement between the photoluminescence excitation spectrum and localized optical absorption of Pb 2+ in isolated [PbBr 6 ] 4− octahedra. Thus, the green photoluminescence is viewed intrinsic to Cs 4 PbBr 6 . Single-and multimode lasing resonances are demonstrated in individual Cs 4 PbBr 6 microcrystals upon optical pumping. Potential application of the Cs 4 PbBr 6 laser is demonstrated to achieve speckle-free imaging of micrometer-scaled objects when a single Cs 4 PbBr 6 microcrystal laser is utilized as the illumination source. The results suggest that zero-dimensional perovskites support lasing resonance and hold important potential applications in optoelectronics.

Micro/nanoscale photonic barcodes based on multicolor luminescent segmented heterojunctions hold potential for applications in information security. However, such multicolor heterojunctions reported thus far are exclusively based on static luminescent signals, thus restricting their application in advanced confidential information protection. Reported here is a strategy to design responsive photonic barcodes with heterobimetallic (Tb3+/Eu3+) metal—organic framework multicolor heterostructures. The spatial colors could be precisely controlled by thermally manipulating the energy‐transfer process between the two lanthanides, thus achieving responsive covert photonic barcodes. Also demonstrated is that spatially resolved responsive barcodes with multi‐responsive features could be created in a single heterostructure. These findings offer unique opportunities to purposely design highly integrated responsive microstructures and smart devices toward advanced anti‐counterfeiting applications.

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Metal-organic frameworks (MOFs) have been used in the area of photovoltaic devices via a novel approach proposed here for the first time. Hierarchical ZnO parallelepipeds were prepared from a MOF precursor, which could then act as an effective light scattering layer in dye-sensitized solar cells, leading to significantly improved cell performance.

NiS nanosheets on ITO substrates were synthesized with in situ growth via a one-step hydrothermal route, and exhibited an efficiency of 7.08% which was comparable to the solar cell based on the Pt electrode (7.01%) under the similar conditions.