We achieved a quantum cutting process in Pr 3+ -Yb 3+ co-doped CaF 2 that converts one visible photon into two near-infrared photons matching the silicon band gap. In this study, the quantum cutting process between Pr 3+ and Yb 3+ was experimentally verified through comparative analysis of the normalized absorption spectrum of Pr 3+ and the near-infrared excitation spectrum of Yb 3+ . Fluorescence lifetime measurements at the optimal doping concentration revealed an energy transfer efficiency of 60.99% from Pr 3+ to Yb 3+ . Temperature-dependent luminescence spectroscopy further estimated the luminescence efficiencies as 64.49% (Pr 3+ ) and 71.41% (Yb 3+ ). Based on these results, the theoretical quantum efficiency of the Pr 3+ →Yb 3+ system was obtained to be about 112.26%, confirming the occurrence of efficient photon down-conversion. Considering the limited energy gain from sunlight due to the narrow-band absorption of Pr 3+ by f-f forbidden transition, Eu 2+ ions were employed to perform broadband sensitization on the quantum cutting process of Pr 3+ -Yb 3+ . Studies have suggested that the incorporation of Eu 2+ can effectively assimilate the 250-400 nm band and transfer energy to Pr 3+ and Yb 3+ , causing them to emit stronger near-infrared spectra. These developed materials are capable of converting ultraviolet-visible photons into near-infrared photons matching the silicon bandgap, which reduces energy loss caused by spectral mismatch and has promising applications in silicon-based photovoltaics.
Qingyang Lu,Shuhong Xu,Haibao Shao,Guangguang Huang,Jingkun Xu,Yiping Cui,Dayan Ban,Chunlei Wang
Large-size luminescent solar concentrators (LSCs), which act as a complement to silicon-based photovoltaic (Si-PV) systems, still suffer from low power conversion efficiency (PCE). How to improve the performance of LSCs, especially large ones, is currently a hot research topic. Traditional LSCs have only a single transmission mode of fluorescence from the luminescent materials to the Si-PV, but here we introduce a new idea to improve the absorption of Si-PV by employing dual transmission modes of both fluorescence and scattering light. To prepare LSCs with dual mode transmission, Si-PV systems are coupled around the edges of a light-harvesting slice, which is prepared by ultraviolet light-induced polymerization of methyl methacrylate (MMA) solution containing both luminescent CsPbBr3 and TiO2 nanocrystals (NCs). When the sun light or incident light is coupled into the light-harvesting slice, CsPbBr3 NCs can convert the incident light into fluorescence, and then partly transmit to Si-PV at the edges, where the light is finally converted into electrical energy. Besides the traditional fluorescence transmission mode, the addition of TiO2 brings another transmission mode, namely the scattering of incident light to Si-PV, leading to an increase in PCE. In comparison to that of pure CsPbBr3-based LSCs without the addition of TiO2 (0.97%), the PCE of TiO2-doped LSCs with a large size of 20 cm × 20 cm is improved to 1.82%. The maximal PCE appears for LSCs with a size of 5 cm × 5 cm, reaching 2.62%. The reported method of dual transmission modes is a new alternative way to improve the performance of LSC devices, which does not need to change the optical properties of luminescent materials. Moreover, the production process is simple, low-cost and suitable for preparing large area LSCs, further promoting the application of LSCs.
Ben Chong,Mengyang Xia,Yang Lv,He Li,Xiaoqing Yan,Bo Lin,Guidong Yang
Transition metal sulfides have always been the promising electrocatalysts for overall water splitting. The regulation of electronic structure and accessibility of active sites are helpful to further boost their electrochemical performance from the aspect of thermodynamics and kinetics, respectively. Herein, we put forward an advanced multi-ion regulation strategy coupled with the morphology management strategy to prepare high performance electrocatalyst with low overpotential and high solar-to-hydrogen STH efficiency. Therefore, a hierarchical nanosheets stacked phosphorus-oxygen incorporated cobalt sulfide (Co-OSP) hollow micro/nano-reactor was designed and synthesized. The experimental results and theoretical calculations indicate that reasonably modulated phosphorus and oxygen extent render the electrocatalyst with optimal conductivity, electron structure and adsorption/desorption behavior of intermediates. In addition, the finite element analysis (FEA) results show that the unique morphology endows the electrocatalyst with fast mass diffusion/transfer pathway and much more accessible active sites. As a consequence, the Co-OSP hollow sphere achieves excellent electrocatalytic water splitting performance with overpotentials as low as 175.3 and 132.7 mV for OER and HER in 1.0 M KOH alkaline solution, respectively. When applied in silicon-based photovoltaic-electrochemical (PV-EC) system, Co-OSP electrodes realizes as high as 9.8 % STH efficiency with cell voltage of 1.48 V. This work presents a potential application in electrocatalysis, lithium batteries , solar cells and other energy-related fields that require catalysts with large exposed surface area and controllable local electric fields. The facile preparation processes and abundant raw materials reserve could increase the commercial viability.
危险品化学品经营许可证（带存储）