近日，浙江大学彭笑刚团队研究了闪锌矿型CdSe基核/壳纳米晶体的超窄均匀光致发光线宽：晶格-配体界面的主导作用。相关论文发表在2025年7月28日出版的《美国化学会志》上。

半导体纳米晶体在室温（~25 meV）下的热致发光（PL）线宽远远大于热展宽，限制了其作为光学和光电子材料的应用。研究组利用单分子光谱研究了外延生长的CdS、ZnSe和ZnS壳层的锌-闪锌矿CdSe纳米晶体的PL均质谱线宽度，证实了电子和空穴波函数在晶格配体界面的离域决定了它们的PL均质谱线宽度。

特别地，外延ZnSe（或ZnSe内部和ZnS外部）外壳与CdSe核心形成i型带偏移，以最小的晶格应变在有序的核心晶格内共定电子和空穴波函数。在没有无序晶格配体界面离域的情况下，这些外延壳使CdSe纳米晶体的均匀PL线宽度减少了约70%。异常窄的均匀PL （~25 meV）实现了观测2-6 nm CdSe的两个最低光学活性态的能量分裂（20~60 meV），呈直角三角形-双锥体形状。这种能量分裂对确定PL均质谱线宽度没有决定性作用，但会导致双峰和极化发射。

附：英文原文

Title: Ultra-Narrow Homogeneous Photoluminescence Line Width of Zinc-Blende CdSe-Based Core/Shell Nanocrystals: Dominating Role of Lattice–Ligands Interface

Author: Yuqing Wang, Jiakuan Zhang, Zihang Chen, Xionglin Zhou, Haixin Lei, Haiyan Qin, Xiaogang Peng

Issue&Volume: July 28, 2025

Abstract: Homogeneous photoluminescence (PL) line width of semiconductor nanocrystals is usually much greater than thermal broadening at room temperature (～25 meV), limiting their applications as optical and optoelectronic materials. Here, homogeneous PL line width of zinc-blende CdSe nanocrystals with epitaxially grown CdS, ZnSe, and ZnS shells is studied using single-molecular spectroscopy, confirming that delocalization of electron and hole wave functions to the lattice–ligands interface dictates their PL homogeneous line width. Specially, epitaxial ZnSe (or ZnSe inner and ZnS outer) shells form type-I band offsets with CdSe cores, colocalizing both electron and hole wave functions within the ordered core lattice with minimum lattice strain. Without delocalization to the disordered lattice–ligands interface, these epitaxial shells reduce the homogeneous PL line width of CdSe nanocrystals by ～70%. Exceptionally narrow homogeneous PL (～25 meV) allows observation of the energy splitting (20～60 meV) of two lowest optically active states of the ground-state exciton for 2–6 nm CdSe in right-triangular-bipyramidal shape. This energy splitting does not play a decisive role in determining the PL homogeneous line width but leads to dual-peak and polarized emission.

DOI: 10.1021/jacs.5c08004

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.5c08004