CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , People's Public of China.
Shenzhen Key Laboratory of Flexible Memory Materials and Devices, College of Electronic Science and Technology , Shenzhen University , Shenzhen , Guangdong 518060 , People's Public of China.
Nano Lett. 2018 Nov 14;18(11):6665-6671. doi: 10.1021/acs.nanolett.8b01001. Epub 2018 Oct 17.
Nanocrystals (NCs) with identical components and sizes but different crystal structures could not be distinguished by conventional absorption and emission spectra. Herein, we find that circular dichroism (CD) spectroscopy can easily distinguish the CdSe nanoplatelets (NPLs) with different crystal structures of wurtzite (WZ) and zincblende (ZB) with the help of chiral l- or d-cysteine ligands. In particular, the CD signs of the first excitonic transitions in WZ and ZB NPLs capped by the same chiral cysteine are opposite. Theoretic calculation supports the viewpoint of different crystal structures and surfaces arrangements between WZ and ZB NPLs contributing to this significant phenomenon. The CD peaks appearing at the first excitonic transition band of WZ or ZB CdSe NPLs are clearly assigned to the different transition polarizations along 4p → 5s or 4p → 5s. This work not only provides a deep insight into the origin of the optical activity inside chiral semiconductor nanomaterials but also proposes the design principle of chiral semiconductor nanocrystals with high optic activity.
具有相同成分和尺寸但晶体结构不同的纳米晶体 (NCs) 无法通过传统的吸收和发射光谱区分。在此，我们发现圆二色性 (CD) 光谱在手性 l-或 d-半胱氨酸配体的帮助下可以轻松区分具有不同晶体结构的纤锌矿 (WZ) 和闪锌矿 (ZB) 的 CdSe 纳米板 (NPL)。特别是，由相同手性半胱氨酸封端的 WZ 和 ZB NPL 中第一激子跃迁的 CD 符号相反。理论计算支持 WZ 和 ZB NPL 之间不同晶体结构和表面排列导致这一显著现象的观点。出现在 WZ 或 ZB CdSe NPL 第一激子跃迁带的 CD 峰明显归因于沿 4p→5s 或 4p→5s 的不同跃迁极化。这项工作不仅深入了解手性半导体纳米材料内部光学活性的起源，还提出了具有高光学活性的手性半导体纳米晶体的设计原则。
