Ghorai Nandan, Ghosh Hirendra N
Institute of Nano Science and Technology, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.
Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Langmuir. 2022 May 10;38(18):5339-5350. doi: 10.1021/acs.langmuir.2c00446. Epub 2022 May 1.
Semiconductor plasmonic nanocrystals (NCs) have been utilized for an enormous number of plasmon-enhanced spectroscopic and energy conversion applications. Plasmonic NCs are extremely high light absorbers, and optical properties can be easily manipulated across the UV-vis-NIR spectrum region by changing mere chemical compositions and the surrounding environment of the NCs. This feature article focuses on reassessing plasmon dynamics by changing the interface composition between NCs and the surrounding medium to ascertain the damping contribution from chemical interface damping (CID). Also, this feature article deciphers a fundamental understanding of hot-carrier relaxation and extraction from plasmonic materials. On the route to determining the different relaxation dynamics of nonstoichiometric CuS/Se NCs, we have employed a transient ultrafast pump-probe broadband spectrometer. First, we have described the ultrafast plasmon relaxation dynamics of nonstoichiometric CuS NCs by varying the copper to sulfur ratio, and then we carefully compare how two surface ligands (oleylamine and 3-mercaptopropionic acid) lead to significantly different transient kinetics of the same plasmonic (CuSe) NCs because of different capping agents. Along with this, we have described the impact of a molecular adsorbate (methylene blue) on ultrafast plasmon relaxation dynamics of the nonstoichiometric CuSe NCs system. Finally, the chemical interface damping effect has been compared in the CuS NCs system after capping with two distinct capping ligands: oleylamine and oleic acid. For the proof of concept, plasmonic thin-film devices were fabricated and exhibited higher conductivity/photoconductivity performance in oleic acid-capped NCs because of a deprotonated carboxyl functional group. We have also introduced a model and mechanism of chemical interface damping in a nonstoichiometric plasmonic semiconductor (CuS/Se) NC system. This feature article highlights the importance of the surface functionalization of nonstoichiometric plasmonic semiconductors to develop new advanced semiconductor-based devices such as infrared photodetectors, plasmonic solar cells, and efficient NIR phototransistors.
半导体等离子体纳米晶体（NCs）已被用于大量等离子体增强光谱和能量转换应用中。等离子体NCs是极强的光吸收体，通过仅仅改变NCs的化学成分和周围环境，其光学性质就能在紫外-可见-近红外光谱区域轻松调控。这篇专题文章着重通过改变NCs与周围介质之间的界面组成来重新评估等离子体动力学，以确定化学界面阻尼（CID）的阻尼贡献。此外，这篇专题文章还解读了对热载流子从等离子体材料中弛豫和提取的基本理解。在确定非化学计量比的CuS/Se NCs不同弛豫动力学的过程中，我们采用了瞬态超快泵浦-探测宽带光谱仪。首先，我们通过改变铜与硫的比例描述了非化学计量比的CuS NCs的超快等离子体弛豫动力学，然后我们仔细比较了两种表面配体（油胺和3-巯基丙酸）如何由于封端剂不同而导致相同等离子体（CuSe）NCs的瞬态动力学显著不同。与此同时，我们描述了分子吸附质（亚甲基蓝）对非化学计量比的CuSe NCs系统超快等离子体弛豫动力学的影响。最后，在用两种不同的封端配体：油胺和油酸封端后，比较了CuS NCs系统中的化学界面阻尼效应。为了验证概念，制备了等离子体薄膜器件，由于去质子化的羧基官能团，在油酸封端的NCs中表现出更高的导电性/光电导性能。我们还介绍了非化学计量比等离子体半导体（CuS/Se）NC系统中化学界面阻尼的模型和机制。这篇专题文章强调了非化学计量比等离子体半导体表面功能化对于开发新型先进半导体基器件（如红外光电探测器、等离子体太阳能电池和高效近红外光电晶体管）的重要性。
