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- 实验方案
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Down-Shifting and Anti-Reflection Effect of CsPbBr3 Quantum Dots/Multicrystalline Silicon Hybrid Structures for Enhanced Photovoltaic Properties
摘要： Over the past couple of decades, extensive research has been conducted on silicon (Si) based solar cells, whose power conversion e?ciency (PCE) still has limitations because of a mismatched solar spectrum. Recently, a down-shifting e?ect has provided a new way to improve cell performances by converting ultraviolet (UV) photons to visible light. In this work, caesium lead bromide perovskite quantum dots (CsPbBr3 QDs) are synthesized with a uniform size of 10 nm. Exhibiting strong absorption of near UV light and intense photoluminescence (PL) peak at 515 nm, CsPbBr3 QDs show a potential application of the down-shifting e?ect. CsPbBr3 QDs/multicrystalline silicon (mc-Si) hybrid structured solar cells are fabricated and systematically studied. Compared with mc-Si solar cells, CsPbBr3 QDs/mc-Si solar cells have obvious improvement in external quantum e?ciency (EQE) within the wavelength ranges of both 300 to 500 nm and 700 to 1100 nm, which can be attributed to the down-shifting e?ect and the anti-re?ection property of CsPbBr3 QDs through the formation of CsPbBr3 QDs/mc-Si structures. Furthermore, a detailed discussion of contact resistance and interface defects is provided. As a result, the coated CsPbBr3 QDs are optimized to be two layers and the solar cell exhibits a highest PCE of 14.52%.
关键词： down-shifting e?ect,solar cell,anti-re?ection property,caesium lead bromide perovskite quantum dots (CsPbBr3 QDs),multicrystalline Si (mc-Si)
更新于2025-09-23 15:19:57
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Design and preliminary operation of a laser absorption diagnostic for the SPIDER RF source
摘要： The ITER Heating Neutral Beam (HNB) injector is required to deliver 16.7 MW power into the plasma from a neutralised beam of H?/D?, produced by an RF source and accelerated up to 1 MeV. To enhance the H? production, the surface of the acceleration system grid facing the source (the plasma grid) will be coated with Cs because of its low work function. Cs will be routinely evaporated in the source by means of specific ovens. Monitoring the evaporation rate and the distribution of Cs inside the source is fundamental to get the desired performances on the ITER HNB. In order to proper design the source of the ITER HNB and to identify the best operation practices for it, the prototype RF negative ion source SPIDER has been developed and built in the Neutral Beam Test Facility at Consorzio RFX. A Laser Absorption Spectroscopy diagnostic will be installed in SPIDER for a quantitative estimation of Cs density. By using a wavelength tunable laser, the diagnostic will measure the absorption spectrum of the 852 nm line along 4 lines of sight, parallel to the plasma grid surface and close to it. From the absorption spectra the line-integrated density of Cs at ground state will be measured. The design of this diagnostic for SPIDER is presented, with details of the layout and of the key components. A preliminary installation of the diagnostic on the test stand for Cs ovens is also described, together with its first experimental results; the effect of ground state depopulation on collected measurements is discussed and partially corrected.
关键词： Laser absorption spectroscopy,Negative ion source,Heating neutral beam,Caesium
更新于2025-09-11 14:15:04
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Double photon emission coincidence imaging with GAGG-SiPM Compton camera
摘要： Compton imaging is a promising gamma-ray imaging method based on the Compton scattering kinematics due to high Compton scattering probability for sub-MeV to MeV gamma-rays. A conventional Compton camera has a disadvantage of low signal-to-background ratio (SBR), which is caused by drawing of multiple Compton cones. A method to solve this fundamental problem is the double-photon emission computed tomography (DPECT), which uses the coincidence detection for cascade gamma-rays and significantly increases the SBR using intersections of two Compton cones. In this study, we demonstrated the DPECT method by using 134Cs radioisotope, which is one of important radioisotopes for the imaging of fuel debris, with two Ce:Gd3(Al,Ga)5O12 (GAGG) scintillator Compton cameras.
关键词： Compton camera,Double photon emission coincidence imaging,Compton imaging,Caesium-134
更新于2025-09-04 15:30:14
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A versatile dual-species Zeeman slower for caesium and ytterbium
摘要： We describe the design, construction, and operation of a versatile dual-species Zeeman slower for both Cs and Yb, which is easily adaptable for use with other alkali metals and alkaline earths. With the aid of analytic models and numerical simulation of decelerator action, we highlight several real-world problems affecting the performance of a slower and discuss effective solutions. To capture Yb into a magneto-optical trap (MOT), we use the broad 1S0 to 1P1 transition at 399 nm for the slower and the narrow 1S0 to 3P1 intercombination line at 556 nm for the MOT. The Cs MOT and slower both use the D2 line (62S1/2 to 62P3/2) at 852 nm. The slower can be switched between loading Yb or Cs in under 0.1 s. We demonstrate that within a few seconds the Zeeman slower loads more than 109 Yb atoms and 108 Cs atoms into their respective MOTs. These are ideal starting numbers for further experiments on ultracold mixtures and molecules.
关键词： caesium,Zeeman slower,dual-species,ytterbium,ultracold atoms,magneto-optical trap
更新于2025-09-04 15:30:14