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  • Vol. 45  期 2, 2024 2024年 45卷 第2期
    • Cover Story

      CHEN Jie,YIN Zhe,WANG Lijin,LI Yu,WANG Shuaibing,LIN Ouyang,TANG Aiwei,TENG Feng

      摘要:Mn ion doping strategy emerged as a widely employed strategy for enhancing the stability of CsPbX3 perovskite nanocrystals (NCs) and regulating Pb content. Nevertheless, the rapid reaction rate associated with ion doping poses significant challenges for controllable synthesis. Herein, we have employed both the one-step and two-step hot injection methods to synthesize CsPbCl3∶Mn2+ NCs with varying levels of Mn2+ doping, allowing for approximate and precise control of Mn2+ incorporation. Through an investigation of their structural and luminescent properties, these NCs are divided into alloy structure and doping structure, elucidating distinct mechanisms involved in one-step and two-step Mn2+ regulation. The alloy structure nanocrystals synthesized by one-step method have higher Mn2+ doping amount than that by two-step method under the same Pb∶Mn feeding ratio. Consequently, the Mn-related emission peak of nanocrystals at about 610 nm is more intense with maximum photoluminescence quantum yield (PLQY) of 77%, and the PLQY of the doped nanocrystals synthesized by the two-step method is also higher in the case of less Mn2+. At the same time, the controlled doping of Mn2+ improves the stability of perovskite nanocrystals, and the original morphology and luminescence properties remained stable after four weeks. Notably, alloy structure is more favorable for improving the luminescence stability of intrinsic excitons compared with doping structure. In addition, CsPb(ClxBr3-x)∶Mn2+ perovskite nanocrystals with excellent luminescent properties have been synthesized. The fluorescence spectrum can be regulated between 404-640 nm, but when the Br- content is high, the emission peak associated with Mn disappears. This is due to the mismatch between the energy band of CsPbBr3 and the 4T1-6A1 energy level of Mn2+. This paper emphasizes the significance of precise Mn2+ doping control in the preparation of CsPbCl3∶Mn2+ perovskite NCs, which is of great significance for the controlled synthesis of nanocrystals.  
      关键词:all-inorganic perovskites;CsPbCl3∶Mn2+;tunable component   
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      发布时间:2024-03-04
    • Research Letter

      SHAN Dongming,ZHANG Hanwen,ZHANG Qingwen,ZHAGN Hu,DING Ran

      摘要:Hybrid perovskite semiconductors have attracted enormous interest in the field of optoelectronic devices for creating high-performance solar cells, light-emitting diodes, and photodetectors owing to their tunable narrow band gap, high optical absorption, high charge-carrier mobility, and low cost, etc. Among them, perovskite single-crystalline thin-films show greater promise as an ideal matrix for optoelectronic applications because of their absence of grain boundaries, lower impurity, and lower defect densities. The space-confined method was usually used for the growth of perovskite single-crystalline thin-films, where a polymer hole-transport layer was employed to accelerate the ion diffusion. However, this solution-processed method will inevitably bring in the interfacial defects and induce poor charge-carrier injection between the perovskite single-crystalline thin-film and hole-transport layer. Herein, we introduced the template stripping method to solve this problem that enables direct thermal-deposition onto two sides of the perovskite single-crystalline thin-film. A novel perovskite single-crystalline thin-film photodetector can be constructed by a device structure of Cu/BCP/C60/MAPbBr3/MoO3/Ag. Then, an ultrasensitive and fast perovskite single-crystalline thin-film photodetector can be realized with an on-off ratio of 3.1 × 103, a responsivity up to 7.15 A/W, a detectivity of 5.39 × 1012 Jones, and an external quantum efficiency of 1794%, due to the optimal device structure and improved charge-carrier transport. These results indicate that the template stripping method provides a feasible approach to further improve the performance of perovskite single-crystal photodetectors.  
      关键词:Hybrid perovskite semiconductors;Perovskite single-crystalline thin-films;Template stripping method;photodetectors   
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      发布时间:2024-03-04
    • ZHAO Jianguo,YIN Rui,XU Ru,NI Haibin,TAO Tao,ZHUANG Zhe,YAN Yu,XIE Zili,LIU Bin,CHANG Jianhua

      摘要:In this paper, polar (0002), semipolar (11-22) and nonpolar (11-20) planes of InN thin films were grown on different planes of sapphire (Al2O3) substrates by using metal-organic chemical vapor deposition (MOCVD) technology, and the structural and optical properties of these InN thin films were intensively investigated by various characterization means. The X-ray diffraction (XRD) curves show the stronger diffraction peaks of the (0002), (11-22) and (11-20) planes of InN, indicating the relatively high crystalline quality of the InN films. The scanning electron microscopy (SEM) surface images reveale that the surface morphology of polar (0002)-plane InN was smoother, while incompletely merged holes were presented on both semipolar and nonpolar InN surfaces. Photoluminescence (PL) spectra demonstrate that the peak energies of different planes of InN were around 0.63 eV and gradually red-shifted from polar, semipolar to nonpolar. In addition, the transmission spectra measured with a visible-infrared spectrophotometer show that the absorption edge of polar (0002)-plane InN is around 0.85 eV, while the absorption edge of semipolar (11-22) and nonpolar (11-20)-planes InN is around 0.78 eV, suggesting a larger Stokes’ shift for polar InN.  
      关键词:semipolar;nonpolar;InN film;epitaxial growth   
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      发布时间:2024-03-04
    • Expert Perspectives

      ALIM Abdurahman,PENG Qiming

      摘要:From the proposing of doublet electroluminescence of free radicals to the successfully achieving of high luminescence efficiency in these materials, and further to developing luminescent diradicals with controllable spin states, this series of innovations have revitalized the field of free radicals that existed a century ago. Here we trace the history of stable organic radicals and provide a detailed account of our research efforts in these unique materials.  
      关键词:organic radicals;stable radicals;doublet emission;OLED;luminescent diradicals   
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      发布时间:2024-03-04
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