Processing-Structure-Property Relationships in Laser-Annealed PbSe Nanocrystal Thin Films.
Processing-Structure-Property Relationships in Laser-Annealed PbSe Nanocrystal Thin Films.
复制标题
激光退火 PbSe 纳米晶体薄膜的加工-结构-性能关系。
DOI：
10.1021/acsnano.5b00167
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发表时间：
2015
期刊：
影响因子：
17.1
通讯作者：
T. Hanrath
中科院分区：
文献类型：
--
作者：
B. Treml;Andrew B. Robbins;K. Whitham;D. Smilgies;M. Thompson;T. Hanrath
随着纳米晶体（NC）合成技术和器件体系结构的进步，越来越明显的是，需要新的方法来连接纳米晶体彼此及其外部环境，以实现其巨大的潜力。通过热退火来增强数控系统间的耦合一直是一个长期存在的挑战。传统的热退火方法受到NC在足够高的温度下退火以去除表面结合配体的挑战，同时限制热预算以防止大规模聚集。在这里，我们研究了NC薄膜的非平衡激光退火，使纳米晶体融合的动力学和热力学方面分离。我们表明，在纳米到微秒的时间尺度上对NC组件进行激光退火，可以将薄膜中最初孤立的NC转变为一个相互连接的结构，在这个结构中，近似的点“只是接触”。我们研究了脉冲激光退火和激光尖峰退火，并表明这两种退火方法都可以产生“封闭但连接”的纳米晶体薄膜。我们开发了一个热输运模型来合理化所产生的薄膜形态的差异。最后，我们证明了从纳米晶体单层和双层研究中获得的见解可以扩展到三维NC薄膜。在这项工作中建立的基本加工-结构-性质关系为未来在创建功能薄膜方面的进展提供了指导，在这些功能薄膜中，组成的nc可以有目的地相互作用。
As nanocrystal (NC) synthesis techniques and device architectures advance, it becomes increasingly apparent that new ways of connecting NCs with each other and their external environment are required to realize their considerable potential. Enhancing inter-NC coupling by thermal annealing has been a long-standing challenge. Conventional thermal annealing approaches are limited by the challenge of annealing the NC at sufficiently high temperatures to remove surface-bound ligands while at the same time limiting the thermal budget to prevent large-scale aggregation. Here we investigate nonequilibrium laser annealing of NC thin films that enables separation of the kinetic and thermodynamic aspects of nanocrystal fusion. We show that laser annealing of NC assemblies on nano- to microsecond time scales can transform initially isolated NCs in a thin film into an interconnected structure in which proximate dots "just touch". We investigate both pulsed laser annealing and laser spike annealing and show that both annealing methods can produce "confined-but-connected" nanocrystal films. We develop a thermal transport model to rationalize the differences in resulting film morphologies. Finally we show that the insights gained from study of nanocrystal mono- and bilayers can be extended to three-dimensional NC films. The basic processing-structure-property relationships established in this work provide guidance to future advances in creating functional thin films in which constituent NCs can purposefully interact.