Synthesis of Monodisperse CdSe Nanocrystals: Nucleation and Growth
-
摘要: 在氩气保护下,用三辛基亚磷酸和油酸分别作为Se和Cd的配位体,在260~300 ℃的十八烯溶液中合成了尺寸可控的CdSe纳米晶。该纳米晶不用进行进一步的提纯和尺寸分离就具有单分散性,其量子尺寸限域效应非常明显吸收光谱的第一吸收峰峰位随着纳米晶的长大而发生红移;该纳米晶质量很高,具有很强的发光能力,其发射光谱对称的形状和合理的Stokes频移(13 nm)显示,该纳米晶的发光完全出自带隙,没有来自缺陷的发光。此外,实验结果表明,通过改变三辛基亚磷酸的浓度可以调节成核和生长的快慢,从而可以在不同的反应时间得到不同尺寸的单分散性CdSe纳米晶。Abstract: With trioctylphosphine and oleic acid as the ligands of Se and Cd, high-quality CdSe nanocrystals with controlled particle size were synthesized in a 260~300 ℃ noncoordinating solvent octadecene under argon flow. The as-synthesized nanocrystals are monodisperse without any size-selective treatment, and exhibit the clear quantum confinement effect, which makes the first excitonic absorption peak shift to red with increasing particle size. The shape of the emission peak and the reasonable Stokes shift (13 nm) indicate that these nanocrystals have intense band-gap emission, devoid of significant trap-state emission. In addition, experimental results show that the rate of nucleation and subsequent growth can be easily tuned by altering the concentration of trioctylphosphine, by which monodisperse CdSe nanocrystals can be also obtained.
-
Key words:
- CdSe nanocrystals /
- semiconductor nanocrystals /
- nucleation /
- growth
-
Huynh W, Peng X G, Alivisatos A P. CdSe Nanocrystal Rods/Poly(3-Hexylthiophene) Composite Photovoltaic Devices [J]. Adv Mater, 1999, 11: 923-927. Sundar V C, Lee J, Heine J R, et al. Full Color Emission from Ⅱ-Ⅵ Semiconductor Quantum Dot-Polymer Composites [J]. Adv Mater, 2000, 12: 1102-1105. Bruchez M, Moronne M, Gin P, et al. Semiconductor Nanocrystals as Fluorescent Biological Labels [J]. Science, 1998, 281: 2013-2016. Murray C B, Norris D J, Bawendi M G. Synthesis and Characterization of Nearly Monodisperse CdE (E=S, Se, Te) Semiconductor Nanocrystallites [J]. J Am Chem Soc, 1993, 115: 8706-8715. Manna L, Scher E C, Alivisatos A P. Synthesis of Soluble and Processable Rod-, Arrow-, Teardrop-, and Tetrapod-Shaped CdSe Nanocrystals [J]. J Am Chem Soc, 2000, 122: 12700-12706. Peng Z A, Peng X G. Formation of High-Quality CdTe, CdSe, and CdS Nanocrystals Using CdO as Precursor [J]. J Am Chem Soc, 2001, 123: 183-184. Kan S H, Mokari T, Rothenberg E, et al. Synthesis and Size-Dependent Properties of Zinc-Blende Semiconductor Quantum Rods [J]. Nature Mater, 2003, 2: 155-158. Yu W W, Peng X G. Formation of High-Quality CdS and Other Ⅱ-Ⅵ Semiconductor Nanocrystals in Noncoordinating Solvents: Tunable Reactivity of Monomers [J]. Angew Chem Int Ed, 2002, 41: 2368-2371. Yu W W, Wang Y A, Peng X G. Formation and Stability of Size-, Shape-, and Structure-Controlled CdTe Nanocrystals: Ligand Effects on Monomers and Nanocrystals [J]. Chem Mater, 2003, 15: 4300-4308. Battaglia D, Peng X G. Formation of High Quality InP and InAs Nanocrystals in a Noncoordinating Solvent [J]. Nano Lett, 2002, 2: 1027-1030. Wu D G, Kordesch M E, van Patten P G. A New Class of Capping Ligands for CdSe Nanocrystal Synthesis [J]. Chem Mater, 2005, 17: 6436-6441. Yu W W, Falkner J C, Shih B S, et al. Preparation and Characterization of Monodisperse PbSe Semiconductor Nanocrystals in a Noncoordinating Solvent [J]. Chem Mater, 2004, 16: 3318-3322. Peng X G, Wickham J, Alivisatos A P, et al. Kinetics of Ⅱ-Ⅵ and Ⅲ-Ⅴ Colloidal Semiconductor Nanocrystal Growth: Focusing of Size Distributions [J]. J Am Chem Soc, 1998, 120: 5343-5344. Dai Q Q, Li D M, Jiang S, et al. Synthesis of Monodisperse CdSe Nanocrystals Directly Open to Air: Monomer Reactivity Tuned by the Selenium Ligand [J]. J Cryst Growth, 2006, 292: 14-18. La Mer V K, Dinegar R H. Theory, Production and Mechanism of Formation of Monodispersed Hydrosols [J]. J Am Chem Soc, 1950, 72: 4847-4854.
点击查看大图
计量
- 文章访问数: 7963
- HTML全文浏览量: 384
- PDF下载量: 912