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Doping of CsPbBr₃perovskite nanocrystals (PNCs) to achieve excellent material properties is accelerating due to their increasing use in optoelectronic devices. Herein, a novel composite of CsPbBr₃PNCs with nickel thiocyanate Ni(SCN)₂is reported, exhibiting stronger photoluminescence (PL) and more extended stability. The addition of Ni(SCN)₂at different molar concentrations reduces the surface trap states of the host PNCs. Therefore, the microstrain, dislocation density, PL emission linewidth, and Urbach energy decrease, resulting in an increased photoluminescence quantum yield (PLQY) from 72% to high above 90%. When stored in the ambient atmosphere for 120 days, the PLQY of doped PNCs is maintained by more than four times compared to host PNCs. A combination of 3D‐printed conversion layers containing green‐, yellow‐, and red‐emitting doped PNCs with blue light‐emitting diodes results in stable white light with superior color qualities. Hence, new composites with desired properties are developed as an alternative to conventional color phosphors.

 

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.

 

The effect of rare earth (RE) single atoms on photocatalytic activity is very complex due to its special electronic configuration, which leads to few reports on the RE single atoms. Here, Dy³⁺single atom composite photocatalysts are successfully constructed based on both the special role of Dy³⁺and the special advantages of CdS/g‐C₃N₄heterojunction in the field of photocatalysis. The results show that an efficient way of electron transfer is provided to promote charge separation, and the dual functions of CO₂molecular activation of rare‐earth single atom and 4flevels as electron transport bridge are fully exploited. It is exciting that under visible‐light irradiation, the catalytic performance of CdS:Dy³⁺/g‐C₃N₄is≈6.9 times higher than that of pure g‐C₃N₄. The catalytic performance of CdS:Dy³⁺and CdS:Dy³⁺/g‐C₃N₄are≈7 and≈13.7 times higher than those of pure CdS, respectively. Besides, not all RE ions are suitable for charge transfer bridges, which is not only related to the 4flevels of RE ions but also related to the bandgap structure of CdS and g‐C₃N₄. The pattern of combining single‐atom catalysis and heterojunction opens up new methods for enhancing photocatalytic activity.

 

Improving the low charge separation efficiency, poor light absorption capacity, and insufficient active sites of photocatalysts are the important challenges for CO 2 photoreduction. In this study, a Mo modified InOOH/In(OH) 3 heterojunction with enhanced CO 2 reduction efficiency was synthesized in situ by using an In(OH) 3 monatomic lamellar material with isolated In atom sites exposed on its surface. And bandgap tuning via the energy levels formed by Mo doping and vacancy defect engineering can simultaneously improve visible light absorption and photogenerated charge separation. The results of experimental characterization and DFT calculation show that the Mo impurity energy levels, O defect energy levels, and surface Mo atoms existing in the InOOH phase can act as an electron transfer ladder in cooperation with the In defect energy levels in the In(OH) 3 phase, thereby promoting electron transfer between heterogeneous interfaces. Under visible light irradiation, the evolution rates of CH 4 and CO of the Mo modified InOOH/In(OH) 3 photocatalyst are more than ∼11 and ∼8 times higher than those of InOOH, respectively. This work provides new insights into the design of the CO 2 photoreduction platform through a collaborative strategy of bandgap tuning, transition metal doping, and heterostructure construction. 

High-quality single-component white phosphors are instrumental in realizing high-efficiency devices. Rare earth fluorides and carbon quantum dots have great potential in the white light-emitting diode (WLED) field due to their unique advantages. Here, Rare-earth single atom based NaGdF4:Tb3+/Eu3+@C:N/Eu3+ single phosphor with tunable full-color luminescence was reported. The results of density functional theory (DFT) calculation and experimental characterization show that C atoms cannot be replaced by Eu3+, but C atoms are more favorable for anchoring Eu3+ single atoms. The DFT was employed to optimize the structures of the C:N/Eu3+ and NaGdF4:Tb3+/Eu3+, and calculate the work function, optical properties, and charge density difference. The obtained tunable full-color single phosphor can emit stable light from blue to red or even white. The constructed WLED devices also have stable and excellent color performance, that is, a color rendering index of up to 95 and a lower color temperature, and it has broad application possibilities in WLEDs. 

Only when the interfacial charge separation is enhanced and the CO 2 activation is improved, can the heterojunction nanocomposite photocatalyst be brought into full play for the CO 2 reduction reaction (CO 2 RR). Here, Er 3+ single atom composite photocatalysts were successfully constructed based on both the special role of Er 3+ single atoms and the special advantages of the SrTiO 3 :Er 3+ /g-C 3 N 4 heterojunction in the field of photocatalysis for the first time. As we expected, the SrTiO 3 :Er 3+ /g-C 3 N 4 (22.35 and 16.90 μmol g −1 h −1 for CO and CH 4 ) exhibits about 5 times enhancement in visible-light photocatalytic activity compared to pure g-C 3 N 4 (4.60 and 3.40 μmol g −1 h −1 for CO and CH 4 ). In particular, the photocatalytic performance of SrTiO 3 :Er 3+ /g-C 3 N 4 is more than three times higher than that of SrTiO 3 /g-C 3 N 4 . From Er 3+ fluorescence quenching measurements, photoelectrochemical studies, transient PL studies and DFT calculations, it is verified that a small fraction of surface doping of Er 3+ formed Er single-atoms on SrTiO 3 building an energy transfer bridge between the interface of SrTiO 3 and g-C 3 N 4 , resulting in enhanced interfacial charge separation. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and adsorption energy calculations demonstrated that the exposed Er single-atoms outside the interface on SrTiO 3 preferentially activate the adsorbed CO 2 , leading to the high photoactivity for the CO 2 RR. A novel enhanced photocatalytic mechanism was proposed, in which Er single-atoms play dual roles of an energy transfer bridge and activating CO 2 to promote charge separation. This provides new insights and feasible routes to develop highly efficient photocatalytic materials by engineering rare-earth single-atom doping.