Kang Sungwoo, Han Seungwu, Kang Youngho
Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Korea.
Department of Materials Science and Engineering, Incheon National University, Incheon 22012, Korea.
ACS Mater Au. 2021 Oct 21;2(2):103-109. doi: 10.1021/acsmaterialsau.1c00034. eCollection 2022 Mar 9.
The luminescence line shape is an important feature of semiconductor quantum dots (QDs) and affects performance in various optical applications. Here, we report a first-principles method to predict the luminescence spectrum of thousands of atom QDs. In our approach, neural network potential calculations are combined with density functional theory calculations to describe exciton-phonon coupling (EPC). Using the calculated EPC, the luminescence spectrum is evaluated within the Franck-Condon approximation. Our approach results in the luminescence line shape for an InP/ZnSe core/shell QD (3406 atoms) that exhibits excellent agreement with the experiments. From a detailed analysis of EPC, we reveal that the coupling of both acoustic and optical phonons to an exciton are important in determining the spectral line shapes of core/shell QDs, which is in contrast with previous studies. On the basis of the present simulation results, we provide guidelines for designing high-performance core/shell QDs with ultrasharp emission spectra.
发光线形是半导体量子点（QDs）的一个重要特征，并且会影响各种光学应用中的性能。在此，我们报告一种预测数千原子量子点发光光谱的第一性原理方法。在我们的方法中，神经网络势计算与密度泛函理论计算相结合来描述激子 - 声子耦合（EPC）。使用计算得到的EPC，在弗兰克 - 康登近似下评估发光光谱。我们的方法得到了一个InP/ZnSe核壳量子点（3406个原子）的发光线形，其与实验结果表现出极好的一致性。通过对EPC的详细分析，我们揭示出声学声子和光学声子与激子的耦合在确定核壳量子点的光谱线形中都很重要，这与先前的研究形成对比。基于当前的模拟结果，我们为设计具有超尖锐发射光谱的高性能核壳量子点提供了指导方针。
