Rational Design of a Near-infrared Fluorescent Material with High Solid-state Efficiency,Aggregation-induced Emission and Live Cell Imaging Property

Near-infrared(NIR) fluorescent materials with high photoluminescent quantum yields(PLQYs) have wide application prospects. Therefore, we design and synthesize a D-A type NIR organic molecule, TPATHCNE, in which triphenylamine and thiophene are utilized as the donors and fumaronitrile is applied as the acceptor. We systematically investigate its molecular structure and photophysical property. TPATHCNE shows high T_gof 110℃ and T_d of 385℃ and displays an aggregation-induced emission(AIE) property. A narrow optical bandgap of 1.65 eV is obtained. The non-doped film of TPATHCNE exhibits a high PLQY of 40.3% with an emission peak at 732 nm, which is among the best values of NIR emitters. When TPATHCNE is applied in organic light-emitting diode(OLED), the electroluminescent peak is located at 716 nm with a maximum external quantum efficiency of 0.83%. With the potential in cell imaging, the polystyrene maleic anhydride(PMSA) modified TPATHCNE nanoparticles(NPs) emit strong fluorescence when labeling HeLa cancer cells, suggesting that TPATHCNE can be used as a fluorescent carrier for specific staining or drug delivery for cellular imaging. TPATHCNE NPs fabricated by bovine serum protein(BSA) are cultivated with mononuclear yeast cells, and the intense intracellular red fluorescence indicates that it can be adopted as a specific stain for imaging.     

n型IBC太阳电池选择性发射极工艺研究

为提升n型叉指背接触(IBC)太阳电池的光电转换效率,采用丝网印刷硼浆和高温扩散的方式形成选择性发射极结构,研究了硼扩散和硼浆印刷工艺对电池发射极钝化性能和接触性能的影响。实验结果表明,在硼扩散沉积时间和退火时间一定的条件下,硼扩散通源(BBr₃)流量为100 mL/min,沉积温度为830 ℃,退火温度为920 ℃时,发射极轻掺杂(p⁺)区域的隐开路电压达到710 mV,暗饱和电流密度为12.2 fA/cm²。发射极局部印刷硼浆湿重为220 mg时,经过高温硼扩散退火,重掺杂(p⁺⁺)区域的隐开路电压保持在683 mV左右,该区域方块电阻仅46 Ω/□,金属接触电阻为2.3 mΩ·cm². 采用该工艺方案制备的IBC电池最高光电转换效率达到24.40%,平均光电转换效率达到24.32%,相比现有IBC电池转换效率提升了0.28个百分点。     

双激光脉冲打靶形成Gd等离子体的极紫外光谱辐射

高端芯片制造所需要的极紫外光刻技术位于我国当前面临35项"卡脖子"关键核心技术之首.高转换效率的极紫外光源是极紫外光刻系统的重要组成部分.本文通过采用双激光脉冲打靶技术实现较强的6.7 nm极紫外光输出.首先,理论计算Gd¹⁸⁺—Gd²⁷⁺离子最外层4d壳层的4p-4d和4d-4f能级之间跃迁、以及Gd¹⁴⁺—Gd¹⁷⁺离子最外层4f壳层的4d-4f能级之间跃迁对波长为6.7 nm附近极紫外光的贡献.其后开展实验研究,结果表明,随着双脉冲之间延时的逐渐增加,波长为6.7 nm附近的极紫外光辐射强度呈现先减弱、后增加、之后再减弱的变化趋势,在双脉冲延时为100 ns处产生的极紫外光辐射最强.并且,在延时为100 ns处产生的光谱效率最高,相比于单脉冲激光产生的光谱效率提升了33%.此外,发现双激光脉冲打靶技术可以有效地减弱等离子体的自吸收效应,获得的6.7 nm附近极紫外光谱宽度均小于单激光脉冲打靶的情形,且在脉冲延时为30 ns时刻所产生的光谱宽度最窄,约为单独主脉冲产生极紫外光谱宽度的1/3.同时...     

环境规制强度影响能源效率的门槛效应研究——基于PSTR模型

利用非径向-SBM和CCR模型测算了我国30个省市(暂不包括西藏和港澳台地区)2007-2016年间的环境规制强度以及能源效率,构建面板平滑转移回归模型(PSTR),分析了环境规制强度对我国能源效率的连续非线性变化的影响.研究结果显示,全国环境规制强度对我国能源效率存在非线性效应,二者之间呈倒“U”型关系.环境规制强度小于门槛值0.6376时,环境规制对能源效率产生创新补偿效应,当环境规制强度高于门槛值0.6376时,环境规制对能源效率产生遵循成本效应.而我国东西部地区的环境规制强度与地区能源效率间却存在着与之相反的“U”型效应.     

CN-Modified Imidazopyridine as a New Electron Accepting Unit of Thermally Activated Delayed Fluorescent Emitters

Two efficient thermally activated delayed fluorescent (TADF) emitters were developed by utilizing CN-modified imidazopyridine as an acceptor unit. The CN-modified imidazopyridine acceptor was combined with either an acridine donor or a phenoxazine donor through a phenyl linker to produce two TADF emitters, Ac-CNImPy and PXZ-CNImPy. The acridine-based Ac-CNImPy emitter exhibited sky-blue emission with a CIE coordinate of (0.18, 0.38), whereas the phenoxazine-donor-based PXZ-CNImPy showed greenish-yellow emission with a CIE coordinate of (0.32, 0.58). A high photoluminescence quantum yield of 80 % was observed for the PXZ-CNImPy emitter compared with 40 % for the Ac-CNImPy emitter. Organic light-emitting diodes based on the PXZ-CNImPy emitter demonstrated high external quantum efficiency of 17.0 %. Hence, the CN-modified imidazopyridine unit can be considered as a useful electron acceptor for the future design of highly efficient TADF emitters.     

单层n型MoS2/p型c-Si异质结太阳电池数值模拟

单层二硫化钼(MoS₂)是一种具有优异光电性能的半导体材料,在太阳能能量转换中表现出很大的应用潜力。本文基于AMPS模拟软件,对单层n型MoS₂/p型c-Si异质结太阳电池进行了数值模拟与分析。通过模拟优化,n型MoS₂的电子亲和能为3.75 eV、掺杂浓度为10¹⁸ cm^-3,p型c-Si的掺杂浓度为10¹⁷ cm^-3时,太阳电池能够取得最高22.1%的转换效率。最后模拟了n型MoS₂/p型c-Si异质结界面处的界面态对太阳电池性能的影响,发现界面态密度超过10¹¹ cm^-2·eV^-1时会严重影响太阳电池的光伏性能。     

Highly Luminescent Red Phosphorescent OLED with Interfacial Layers for Hole Transport and Electron Injection

Four kinds of red phosphorescent organic light-emitting devices were fabricated and compared to investigate the effect of interfacial layers for hole transport and electron injection. 1 nm-thick LiF in the device A and C and 1 nm-thick Cs₂CO₃ in the device B and D were deposited as an electron injection layer between the anode and the electron transport layer, and 5 nm-thick layer of dipyrazion[2,3-f:2′,2′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile[HATCN] was inserted as a hole transport interfacial layer between the hole injection layer and the hole transport layer only in the device C and D. Under a luminance of 1000 cd/m², the power efficiencies were 7.6 lm/W and 8.5 lm/W in the device A and B, and 8.6 lm/W and 13.4 lm/W in the device C and D. The quantum efficiency of the device D was 15.8% under 1000 cd/m² which was somewhat lower than those of the device A and C, but a little higher than that of the device B. The luminance of the device D was much higher than those of the other devices at a given votage. The luminance of the device D at 7 V was 23,710 cd/m², which was 13.0, 3.4, and 4.0 times higher than those of the device A, B, and C at the same voltage, respectively.     

A rapid dissolution procedure to aid initial nuclear forensics investigations of chemically refractory compounds and particles prior to gamma spectrometry

A rapid and effective preparative procedure has been evaluated for the accurate determination of low-energy (40–200 keV) gamma-emitting radionuclides (²¹⁰Pb, ²³⁴Th, ²²⁶Ra, ²³⁵U) in uranium ores and uranium ore concentrates (UOCs) using high-resolution gamma ray spectrometry. The measurement of low-energy gamma photons is complicated in heterogeneous samples containing high-density mineral phases and in such situations activity concentrations will be underestimated. This is because attenuation corrections, calculated based on sample mean density, do not properly correct where dense grains are dispersed within a less dense matrix (analogous to a nugget effect). The current method overcomes these problems using a lithium tetraborate fusion that readily dissolves all components including high-density, self-attenuating minerals/compounds. This is the ideal method for dissolving complex, non-volatile components in soils, rocks, mineral concentrates, and other materials where density reduction is required. Lithium borate fusion avoids the need for theoretical efficiency corrections or measurement of matrix matched calibration standards. The resulting homogeneous quenched glass produced can be quickly dissolved in nitric acid producing low-density solutions that can be counted by gamma spectrometry. The effectiveness of the technique is demonstrated using uranium-bearing Certified Reference Materials and provides accurate activity concentration determinations compared to the underestimated activity concentrations derived from direct measurements of a bulk sample. The procedure offers an effective solution for initial nuclear forensic studies where complex refractory minerals or matrices exist. It is also significantly faster, safer and simpler than alternative approaches.     

Atomic-Scale Dispersed Fe-Based Catalysts Confined on Nitrogen-Doped Graphene for Li-S Batteries: Polysulfides with Enhanced Conversion Efficiency

Lithium-sulfur batteries have been considered as potential electrochemical energy-storage devices owing to their satisfactory theoretical energy density. Nonetheless, the inferior conversion efficiency of polysulfides in essence leads to fast capacity decay during the discharge/charge cycle. In this work, it is successfully demonstrated that the conversion efficiency of lithium polysulfides is remarkably enhanced by employing a well-distributed atomic-scale Fe-based catalyst immobilized on nitrogen-doped graphene (Fe@NG) as a coating of separator in lithium-sulfur batteries. The quantitative electrocatalytic efficiency of the conversion of lithium polysulfides is determined through cyclic voltammetry. It is also proven that the Fe-N_X configuration with highly catalytic activity is quite beneficial for the conversion of lithium polysulfides. In addition, the adsorption and permeation experiments distinctly indicate that the strong anchoring effect, originated from the charge redistribution of N doping into the graphene matrix, inhibits the movement of lithium polysulfides. Thanks to these advantages, if the as-prepared Fe@NG catalyst is combined with polypropylene and applied as a separator (Fe@NG/PP) in Li-S batteries, a high initial capacity (1616 mA h g⁻¹ at 0.1 C), excellent capacity retention (93 % at 0.2 C, 70 % at 2 C), and superb rate performance (820 mA h g⁻¹ at 2 C) are achieved.