纳米晶体的光致发光线形：来自一阶和二阶振动耦合的贡献
Photoluminescence Line Shapes of Nanocrystals: Contributions from First- and Second-Order Vibronic Couplings
AI总结：
本文提出一种参数无关的方法，用于计算纳米晶体的光致发光光谱，揭示二次声子耦合对谱线宽的影响。
摘要：
我们提出了一种微观的、参数无关的方法，用于计算单个半导体纳米晶体的光致发光光谱。该方法直接从半经验伪势框架中推导出激子-声子耦合，并系统地纳入了对角线和非对角线相互作用，扩展到声子模式的二阶。通过在Kubo-Toyozawa形式中使用Dyson展开计算偶极子-偶极子相关函数，使纯退相干和人口转移在光致发光光谱特征中的作用得到一致描述。应用于CdSe/CdS核壳纳米晶体，该方法在宽温度范围内定量重现了实验光致发光光谱，揭示了二次声子耦合在100-150K以上的均匀线宽中占将近一半，而非对角线耦合导致激子热化仅起次要作用，仅在温度接近300K时才有所体现。
英文摘要：
We present a microscopic, parameter-free approach for computing the photoluminescence spectra of a single semiconductor nanocrystal. The method derives exciton-phonon coupling directly from the semi-empirical pseudopotential framework and systematically incorporates both diagonal and off-diagonal interactions, expanded to second-order in the phonon modes. The dipole-dipole correlation function was calculated using a Dyson expansion within the Kubo-Toyozawa formalism, enabling a consistent description of the role of pure dephasing and population-transfer on the photoluminescence spectral features. Applied to CdSe/CdS core-shell nanocrystals, the approach quantitatively reproduces experimental photoluminescence spectra over a wide temperature range, revealing that quadratic phonon couplings account for nearly half of the homogeneous linewidth above 100-150 K, while off-diagonal couplings leading to exciton thermalization play only a minor role and only as T approaches 300K.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
