Research Progress on Stability of PbS Colloidal Quantum Dots
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摘要: PbS胶体量子点由于其制备简单、成本低廉,在近红外波段通过调节尺寸就能改变带隙,在太阳能电池、红外探测、LED、生物成像等多个领域均有广泛的应用,但稳定性限制了其大规模推广。本文总结了影响PbS胶体量子点稳定性的机理,从制备、结构、保存、使用等多个环节探讨提高其稳定性的具体措施。提出进一步改进PbS胶体量子点稳定性的具体方法和原理,对其应用和发展具有一定的参考价值。Abstract: Due to the simple preparation, low cost, and adjustable bandgap via changing their sizes in the near-infrared band, PbS colloidal quantum dots (QDs) have been widely used in many fields such as solar cell, infrared detection, LED, and biological imaging. However, instability limits further practical application. In this study, the instability mechanism of PbS colloidal QDs was investigated, and measures to improve their stability are discussed in terms of preparation, structure, preservation, and application. Measures and mechanisms for further improving stability are proposed, which have great value for their application and development.
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Key words:
- PbS colloidal QDs /
- applications of colloidal QDs /
- stability /
- core-shell structure
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图 1 PbS胶体量子点的应用:(a) 太阳能电池领域[4];(b) 红外探测器领域[11];(c) 含PbS胶体量子点的LED结构[14];(d) 另一种基于PbS胶体量子点的LED结构[17];注射了量子点的小白鼠的(e)可见光成像;(f)红外成像和(g)融合成像[20]
Figure 1. The Application of PbS colloidal QDs: (a) Solar cell field[4]; (b) Infrared detection field[11]; (c) The LED structure based PbS colloidal QDs[11]; (d) Another LED structure based PbS colloidal QDs[14]; The (e) optical, (f) fluorescence, and (g) merged images of the mouse after injection with the QD solution[20]
图 2 PbS胶体量子点:(a) 热注入法生产PbS胶体量子点;(b) PbS/CdS核壳结构;(c) PbS/CdS/ZnS核壳结构;(d) PbS胶体量子点中氧诱导的间隙态[35]
Figure 2. PbS colloidal QDs: (a) Producing PbS colloidal QDs by heat injection; (b) PbS/CdS core/shell structure; (c) PbS/CdS/ZnS core/shell structure; (d) In-gap states[35] induced by O2 in PbS colloidal QDs
图 3 PbS胶体量子点的尺寸与形状:(a) PbS胶体量子点尺寸与形状的关系[30];(b) 八面体结构的PbS胶体量子点;(c) 八面体表面原子展开图;(c) 立方八面体结构的PbS胶体量子点;(d) 立方八面体的表面原子展开图
Figure 3. Size and shape of PbS colloidal QDs: (a) Diagram of shape versus size about PbS colloidal QDs[30]; (b) PbS colloidal QDs with octahedral structure; (c) Expansion of octahedral surface atomic; (d) PbS colloidal QDs with cuboctahedral structure; (e) Expansion of cuboctahedral surface atomic
表 1 增强PbS胶体量子点稳定性的技巧
Table 1. Skills to enhance stability of PbS colloidal QDs
Skills Descriptions Characteristics References a) Improving the preparation condition The amount of O2 and H2O in the preparation environment is reduced via selecting appropriate raw materials and adjusting the preparation atmosphere. The premise of successfully preparing PbS colloidal QDs [38, 45-47] b) Controling particle size The ideal crystal plane appears on the outer surface of the QDs via controlling the reaction conditions and the metrological ratio of Pb and S. Fixed absorption band, and only used in applications that are insensitive to the bands [30, 31] c) Core/shell structure A more stable shell surrounds the PbS colloidal QDs via cation exchanging. The complicated preparation process
Reducing the toxicity of PbS and improving solubility in aqueous solution
Mostly used in biological field[38, 40, 41] d) Surface passivation Ligand exchanging
Halogen ligands are often used in the range of inorganic ligands.Reducing hydroxyl groups on the surface of QDs
No photoconductance gain
Commonly used in photovoltaic devices[4, 48] e) Improving the operating environment Encapsulation. Using in fields of small-sized photodetectors and LED [11] -
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