学术报告（6月7日）

摘要：Understanding of the electronic and optical properties of nanoscale optoelectronic device is imperative for further optimization of their performance. In this talk, I will present our development of quantum mechanical approaches for modeling photovoltaic effect (PV) and electroluminescence (EL) processes in nanoscale. Based on nonequilibrium Green's function quantum transport equation, the light-matter interaction is included to describe the energy conversion in the devices under non-equilibrium condition. The reliability of our method is illustrated by numerical simulations of silicon nanowire based solar cells and LED devices. EL spectra of the nanowire under different bias voltage are obtained and, more importantly, radiation pattern and polarization of optical emission can be determined using our approach. Our work is a step forward towards atomistic quantum mechanical modeling of light-induced current and electrically induced optical response in nanoscale system. Moreover, a novel theory is developed to describe the energy conversion of plasmonic hot-carrier solar cell, which is used to study the fundamental limitations to plasmonic hot-carrier solar cells. The numerical results indicate this cell can significantly improve the absorption of solar radiation but it suffers from low internal quantum efficiency as plasmon excitation creates a broad distribution of hot electron/hole energies. The connection of these results to recent experiments will also be described.

References:

[1] Yu Zhang, Lingyi Meng, ChiYung Yam and GuanHua Chen, “Quantum-Mechanical Prediction of Nanoscale Photovoltaics” J. Phys. Chem. Lett.2014, 5, 1272-1277.

[2] Ruling Wang, Yu Zhang, Fuzhen Bi, GuanHua Chen and ChiYung Yam, “Quantum Mechanical Modeling of Nanoscale Light Emitting Diodes” arXiv.1512.08498, Nanoscale, in press.

[3] Yu Zhang, ChiYung Yam and George C. Schatz. “Fundamental Limitations to Plasmonic Hot-Carrier Solar Cells” J. Phys. Chem. Lett. 2016, 7, 1852-1858.

报告人简介：

张余

2010年　　　beat365中国唯一官方网站物理学学士

2014年　　　香港大学化学物理博士

2015年至今　美国西北大学博士后