安徽建筑大学材料与化学工程学院, 安徽 合肥 230601
纯有机室温磷光由于其独特的长余辉性质, 在数据加密、 防伪、 有机发光二极管以及细胞成像等应用领域引起了广泛关注。 目前, 设计具有高亮磷光和超长发光时间的有机材料仍然是一个巨大的挑战。 基于重原子效应, 设计与合成了一种纯有机室温磷光分子1,4-二溴-2,5-二氟二(9H-咔唑-9-基)苯(BFCzB), 该化合物在日光下为白色粉末, 紫外灯开、 关后发射明亮黄色磷光, 其最大激发波长为366 nm, 对应的最大发射波长为544 nm, 在590和640 nm还存在两处肩峰, 其寿命为103.55 ms, 余辉接近2 s。 为了探讨重原子引入对磷光的影响, 在(TD)DFT(含时密度泛函理论)上进行了理论模拟, 通过模拟计算可得出HOMO/LUMO的带隙仅为0.02 eV, 说明分子易被激发, 通过与相似无卤素化合物的比较, 引入卤素后能带隙的减弱证明重原子的引入有助于促进单线态和三线态间的自旋轨道耦合(SOC)和系间窜越(ISC)。 为进一步探究BFCzB超长磷光的起源, 进行了粉末X射线衍射(XRD)光谱测试以了解分子堆积模型和存在的相互作用。 对于BFCzB分子, 存在3种类型的分子内相互作用, 包括C-Br…π (3.373 1 )卤键、 C-Br…N (3.170 5 )卤键和C-F…H-C (2.587 7 )氢键。 这些相互作用有效地限制了分子的旋转与振动, 进而极大地降低了非辐射驰豫。 此外, BFCzB分子中卤素原子与相邻分子间还存在着众多分子间相互作用。 C-F与相邻分子的咔唑环形成主要的相互作用C-F…H-C (2.527 1 )氢键和C-F…π(2.933 5和3.049 4 )卤键, Br与相邻分子也存在着C-Br…H-C (2.846 6 )氢键和C-Br…π(3.531 4 )卤键相互作用。 邻近分子的咔唑基团还存在着π…π堆积(3.399 2 )。 所有这些分子内和分子间的相互作用共同抑制分子运动, 进一步抑制了三重态激子的非辐射弛豫, 实现了超长室温磷光。 该工作还通过TMB比色法验证BFCzB分子的磷光在水中猝灭时产生单重态氧(1O2), 并基于此进行光动力学抗菌实验。 本研究可为纯有机磷光分子的设计、 合成和应用提供借鉴。
纯有机化合物 室温磷光 重原子效应 光动力学抗菌 Purely organic compounds Room temperature phosphorescence (RTP) Heavy atomeffect Photodynamic antibacteria 光谱学与光谱分析
2023, 43(9): 2910
1 宿迁学院 材料工程系，宿迁 223800
2 南京理工大学 材料科学与工程学院，南京 210094
为克服在大批量合成无机钙钛矿量子点（CsPbBr3）时出现的材料光学性能下降的问题，提出了一种改进的室温溶液工艺，通过加入HBr促进前驱体的分散溶解，同时引入路易斯酸配体部分取代油胺，实现量子点表面的缺陷态有效钝化，合成出高质量的CsPbBr3量子点材料。实验测试结果表明，合成出的CsPbBr3量子点荧光发射峰位于517 nm处，发射峰半高宽仅有17 nm，荧光量子效率高达95%。利用制备出的绿光CsPbBr3量子点和商用红色荧光粉混合，和以GaN为基底的蓝光芯片组装成一个白光LED器件，该器件在20 mA的工作电流下获得流明效率达48.35 lm/W的白光。这种高效白光LED展示出无机钙钛矿量子点在通用照明、背光显示和光通信等领域中具有很大的应用潜力。
钙钛矿量子点 室温溶液法 批量合成 白光LED Perovskite quantum dots Solution-process at room temperature Mass synthesis WLED 光子学报
2023, 52(11): 1116002
1 中国科学院福建物质结构研究所, 福州 350002
2 中国科学院大学, 北京 100039
随着电子信息技术的飞速发展, 具有更高抗干扰能力以及更高灵敏度的日盲紫外探测器引起了广泛关注。六方相氮化硼(h-BN)凭借其超宽带隙、高光吸收系数、高热导率及高击穿场强等优势成为日盲紫外探测器研究的热点材料。此外, h-BN良好的机械强度和光学透明性使其兼具柔性探测器的潜力。然而室温条件下制备的h-BN薄膜常具有较多缺陷, 极大程度上限制了其柔性探测器的发展。本文在室温条件下采用反应磁控溅射, 以B为生长源, 在蓝宝石和Si衬底上实现了较高质量h-BN薄膜的制备, 并在此薄膜的基础上制备了高性能日盲紫外探测器。3 V电压下, 其探测器拥有极低的暗电流(0.07 pA)、较高的响应度(1.37 μA/W)和探测率(2.73×1010 Jones)。本文的研究结果证实了室温制备h-BN薄膜及其日盲紫外探测器的可行性, 为实现可在室温下工作的h-BN探测器的应用提供了参考。
h-BN薄膜 反应溅射法 室温 日盲紫外探测器 光电性能 响应度 h-BN film reactive sputtering method room temperature solar-blind ultraviolet detector photoelectric property responsivity
沈阳工业大学机械工程学院，辽宁 沈阳 110870
对TC4钛合金激光增材修复试样进行不同方向的组织、显微硬度及室温拉伸性能分析。结果表明：激光增材修复区为典型的网篮组织，增材高度方向增材区为细密的网篮组织，倾斜方向增材区的网篮组织内包含部分等轴α相，扫描方向试样由于热量累积少，散热快，且靠近结合区，由大量细长α板条以及部分针状α′组成。增材区显微硬度以扫描方向试样为最大，约为345 HV，比增材高度方向和倾斜方向试样高出4.1%；扫描方向试样结合区的显微硬度最高，达到362 HV。不同方向试样室温拉伸性能存在各向异性，扫描方向试样抗拉强度高，塑性略低，增材高度方向和倾斜方向试样抗拉强度低，塑性略高。断口均表现出韧性断裂。
激光增材修复 TC4钛合金 显微组织 显微硬度 室温拉伸性能 laser additive repair Ti-6Al-4V microstructure microhardness room-temperature tensile property
Author Affiliations
Abstract
1 State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
Colloidal CdSe quantum dots (QDs) are promising materials for solar cells because of their simple preparation process and compatibility with flexible substrates. The QD radiative recombination lifetime has attracted enormous attention as it affects the probability of photogenerated charges leaving the QDs and being collected at the battery electrodes. However, the scaling law for the exciton radiative lifetime in CdSe QDs is still a puzzle. This article presents a novel explanation that reconciles this controversy. Our calculations agree with the experimental measurements of all three divergent trends in a broadened energy window. Further, we proved that the exciton radiative lifetime is a consequence of the thermal average of decays for all thermally accessible exciton states. Each of the contradictory size-dependent patterns reflects this trend in a specific size range. As the optical band gap increases, the radiative lifetime decreases in larger QDs, increases in smaller QDs, and is weakly dependent on size in the intermediate energy region. This study addresses the inconsistencies in the scaling law of the exciton lifetime and gives a unified interpretation over a widened framework. Moreover, it provides valuable guidance for carrier separation in the thin film solar cell of CdSe QDs.Colloidal CdSe quantum dots (QDs) are promising materials for solar cells because of their simple preparation process and compatibility with flexible substrates. The QD radiative recombination lifetime has attracted enormous attention as it affects the probability of photogenerated charges leaving the QDs and being collected at the battery electrodes. However, the scaling law for the exciton radiative lifetime in CdSe QDs is still a puzzle. This article presents a novel explanation that reconciles this controversy. Our calculations agree with the experimental measurements of all three divergent trends in a broadened energy window. Further, we proved that the exciton radiative lifetime is a consequence of the thermal average of decays for all thermally accessible exciton states. Each of the contradictory size-dependent patterns reflects this trend in a specific size range. As the optical band gap increases, the radiative lifetime decreases in larger QDs, increases in smaller QDs, and is weakly dependent on size in the intermediate energy region. This study addresses the inconsistencies in the scaling law of the exciton lifetime and gives a unified interpretation over a widened framework. Moreover, it provides valuable guidance for carrier separation in the thin film solar cell of CdSe QDs.
solar cells CdSe quantum dot radiative lifetime scaling law optical band gap exciton fine structure room temperature Journal of Semiconductors
2023, 44(3): 032702
Author Affiliations
Abstract
1 Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, People’s Republic of China
2 Research Office of Propulsion Technology, Expace Technology Corporation Limited, Beijing 100176, People’s Republic of China
3 Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
4 School of Metallurgy, Northeastern University, Shenyang 100819, People’s Republic of China
5 Institut für Materialwissenschaft, Technische Universitt Darmstadt, Darmstadt 64283, Germany
6 School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, People’s Republic of China
Two-dimensional (2D) thermoelectric (TE) materials have been widely developed; however, some 2D materials exhibit isotropic phonon, electron transport properties, and poor TE performance, which limit their application scope. Thus, exploring excellent anisotropic and ultrahigh-performance TE materials are very warranted. Herein, we first investigate the phonon thermal and TE properties of a novel 2D-connectivity ternary compound named Ga2I2S2. This paper comprehensively studies the phonon dispersion, phonon anharmonicity, lattice thermal conductivity, electronic structure, carrier mobility, Seebeck coefficient, electrical conductivity, and the dimensionless figure of merit (ZT) versus carrier concentration for 2D Ga2I2S2. We conclude that the in-plane lattice thermal conductivities of Ga2I2S2 at room temperature (300 K) are found to be 1.55 W mK-1 in the X-axis direction (xx-direction) and 3.82 W mK-1 in the Y-axis direction (yy-direction), which means its anisotropy ratio reaches 1.46. Simultaneously, the TE performance of p-type and n-type doping 2D Ga2I2S2 also shows significant anisotropy, giving rise to the ZT peak values of p-type doping in xx- and yy-directions being 0.81 and 1.99, respectively, and those of n-type doping reach ultrahigh values of 7.12 and 2.89 at 300 K, which are obviously higher than the reported values for p-type and n-type doping ternary compound Sn2BiX (ZT ～ 1.70 and ～2.45 at 300 K) (2020 Nano Energy 67 104283). This work demonstrates that 2D Ga2I2S2 has high anisotropic TE conversion efficiency and can also be used as a new potential room-temperature TE material.
thermoelectricity strong anisotropy two-dimensional materials room temperature first-principles calculation International Journal of Extreme Manufacturing
2022, 4(2): 025001
江西铜业技术研究院有限公司，江西 南昌 330096
目前大多数柔性薄膜晶体管（TFT）使用塑料基板替代玻璃基板会导致白色污染加重，本研究采用可降解的纳米纤维素纸作为柔性基板，其具有粗糙度仅为3.12 nm的优异平滑度，且整个器件沉积完后只增加至6.03 nm。更重要的是，该TFT器件通过磁控溅射制备IGZO/Al2O3作为有源层，使得器件在室温下无需热退火处理，避免了纳米纸不耐高温的问题。在有源层中，Al2O3充当电子桥连接了不连续的铟镓锌氧化物（IGZO），且IGZO有着微弱的结晶，大量的载流子得以沿沟道流通。该纸基器件展示出迁移率为22.5 cm2/（V·s）、开关比高达5.07×106、阈值电压Vth仅为-0.036 V的优异性能，并且有着很好的正偏压和负偏压稳定性。这种纸基TFT在未来的绿色且柔性显示中具有巨大的应用潜力。
薄膜 铟镓锌氧化物 薄膜晶体管 纳米纸 室温制备 激光与光电子学进展
2022, 59(19): 1931002
武汉理工大学材料科学与工程学院, 武汉 430070
本文采用四丁基氢氧化铵催化碱法制备富勒醇, 并以富勒醇为原料, 采用溶胶凝胶法制备富勒醇修饰氮掺杂二氧化钛光催化材料, 对该复合材料的成分、结构等进行表征与分析, 并研究复合材料的光催化还原CO2的性能。结果表明, 复合材料在可见光区的光吸收性能增强, 表现出良好的室温可见光催化还原CO2活性, 其中CO平均生成速率达5.560 μmol·g-1·h-1, CH4平均生成速率为0.789 μmol·g-1·h-1。分析认为, 富勒醇复合与N掺杂有效提高了TiO2的可见光催化活性。
光催化还原CO2 富勒醇 氮掺杂 二氧化钛 溶胶凝胶法 室温 可见光 photocatalytic reduction of CO2 polyhydroxylated fullerenes nitrogen doping titanium dioxide sol-gel method room temperature visible light
