A novel near-infrared (NIR) quantum cutting (QC) Ca 2 BO 3 Cl:Ce 3+ ,Tb 3+ ,Yb 3+ phosphor promising for luminescent solar concentrators (LSC) with Si solar cells was successfully developed. It can harvest UV photons and exhibits an intense NIR emission of Yb 3+ around $1000 nm, perfectly matching the maximum spectral response of Si solar cells. The NIR emission intensity of Ca 2 BO 3 Cl:Ce 3+ ,Tb 3+ , Yb 3+ upon broadband excitation of Ce 3+ ion at 288, 315 and 369 nm is about 9.1, 10 and 2.8 times as intense as that of GdBO 3 :Tb 3+ ,Yb 3+ with the highest NIR quantum efficiency of about 182% upon narrow excitation of Tb 3+ ion at 488 nm. It demonstrates for the first time that Ce 3+ ion can be an efficient sensitizer harvesting UV photons and greatly enhancing the NIR emission of Yb 3+ ion through efficient energy feeding by the allowed 4f-5d absorption of Ce 3+ ion with high oscillator strength. We believe this new NIR QC phosphor may open a new route to the design of advanced NIR QC phosphors for maximizing LSC performance with Si solar cells.

Ce 3+ -doped Ba 2 Ln(BO 3 ) 2 Cl (Ln ¼ Gd, Y) phosphors were synthesized through a conventional hightemperature solid state method in CO atmosphere. Structural and spectroscopic characterizations of the samples have been performed by X-ray diffraction and photoluminescence spectra measurements. The phosphors can be efficiently excited by near ultraviolet (n-UV) light resulting in blue emission. The optimal Ce 3+ dopant concentrations in both compounds were determined, and the concentration quenching mechanisms were also discussed. The photoluminescence excitation (PLE) and emission (PL) spectra, and decay curves at liquid helium temperature were measured to analyze the crystallographic occupancy sites of Ce 3+ in the Ba 2 Ln(BO 3 ) 2 Cl (Ln ¼ Gd, Y) hosts. The thermal stabilities of the phosphors Ba 2 Ln(BO 3 ) 2 Cl:Ce 3+ (Ln ¼ Gd, Y) were studied using the dependence of the luminescence intensities on temperature (300-500 K), and their luminescence quenching temperatures and thermal activation energies were also determined. The results indicate that the phosphor Ba 2 Gd(BO 3 ) 2 Cl:Ce 3+ offers excellent optical properties as a potential blue-emitting phosphor candidate for n-UV LEDs, such as a higher thermal stability and a stronger luminescence intensity, than those of the phosphor Ba 2 Y(BO 3 ) 2 Cl:Ce 3+ .

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This study investigated the photoluminescent properties of Tb(3+)-Yb(3+)-, Ce(3+)-Tb(3+)-Yb(3+)-, and Eu(2+)-Yb(3+)-doped KSrPO4. The samples were prepared by a solid-state reaction with various doping concentrations. Emission at near-infrared range was focused on the application of luminescent solar concentrator for solar cells. Quantum cutting (QC) energy transfer was confirmed by the lifetimes of the donor. Near-infrared QC involved emission of Yb(3+) ions was achieved by excitation of Ce(3+), Tb(3+), and Eu(2+) ions, where the energy transfer processes occurred from Ce(3+) to Tb(3+) to Yb(3+), Tb(3+) to Yb(3+), and Eu(2+) to Yb(3+), respectively. In addition, the concentration quenching effect of Yb(3+) ions was avoided by low doping concentrations. The overall quantum efficiencies were calculated, and the maximum efficiency reaches 139%. The energy diagrams for divalent and trivalent rare-earth ions in KSrPO4 host lattice were analyzed. Results of this study demonstrate that heat-stable phosphate phosphors are promising candidates for increasing the efficiency of silicon-based solar cells.

Gold–copper (Au‐Cu) Janus nanostructures (Au‐Cu Janus NSs) are successfully prepared using N‐oleyl‐1,3‐propanediamine as capping agent and Cu(acac)2 as the precursor in a typical seeded growth strategy. By preferably depositing Cu atoms on one side of concave cubic Au seeds, the Cu part gradually grows larger as more Cu precursors are added, making the size tuning feasible in the range of 74–156 nm. When employed as an electrocatalyst for electrochemical CO2 reduction (CO2RR), the Au‐Cu Janus NSs display superior performance to Au@Cu core‐shell NSs and Cu NPs in terms of C2+ products selectivity (67%) and C2+ partial current density (−0.29 A cm–2). Combined experimental verification and theoretical simulations reveal that CO spillover from Au sites to the nearby Cu counterparts would enhance CO coverage and thus promote C–C coupling, highlighting the unique structural advantages of the Au‐Cu Janus NSs toward deep reduction of CO2. The current work provides a facile strategy to fabricate tandem catalyst with a Janus structure and validates its structural advantages toward CO2RR, which are of critical importance for the rational design of efficient CO2RR catalyst.