报告人：秋山英文 院士
主持人：陈少强 教授
时间：2025年12月9日15:30-16:30
地点：信息楼魔方厅
报告人简介：秋山英文院士于1991年在日本东京大学物理系获得博士学位，1991-1996年任东京大学先端科学技术中心助理教授，1996-2016年任东京大学物性研究所副教授，2000-2005年任美国贝尔物理实验室访问教授，2016年至今任东京大学物性研究所教授、曾任东京大学先端分光中心主任、东京大学校长助理等职务，2024年入选日本工程院院士。所从事的研究领域包括新型半导体光电器件、精密光学检测等，曾利用分子束外延技术制备出具有世界最高质量的砷化镓量子线，并实现了超低阈值的激光发射。在Nature Photonics、Phys.Rev.Lett等期刊杂志上共发表SCI论文300余篇。
报告内容介绍：The record efficiency for III-V multi-junction solar cells for a three-junction solar cell reached 39.5% under unconcentrated light conditions. Absolute electroluminescence (EL) measurement is effective for quantitatively characterizing quality of new materials and new cells. We are currently working on basic research of this method, and are also exploring the development and application of absolute EL standard cells to promote the widespread use of this method. EL study of solar cells has become widespread as EL imaging measurements for diagnosing local defects as electrode defects and cracks in solar cells. We have researched and developed a method for measuring the absolute EL of solar cells, i.e., the external radiative efficacy (ERE) during LED operation, and directly evaluating the internal voltage and material quality from the absolute EL data. Obtaining absolute EL images and absolute EL values (total flux) of solar cells enable extensive diagnostics and design feedback, including internal voltage (open circuit voltage and I-V relationship), internal material quality, luminescence coupling, and analysis of losses within the cells, without the need to apply a voltage probe to the cells. Combining this with steady-state PL and time-resolved PL measurement results enable more detailed diagnosis. In fact, in recent years, we have been researching and developing methods for time-resolved evaluation of the impulse response of internal voltage (photovoltaic power) to gain a deeper understanding. In addition, by taking advantage of on-site non-contact testing ability, we may quantitatively evaluate the deterioration and damage of solar cells of existing solar power generation facilities over time, which will be useful for evaluating the equipment's lifespan and predicting when to replace them. Absolute EL or ERE measurement is a useful technique that provides a wealth of information, and data are now often included in papers reporting world-record efficiencies for multi-junction solar cells made of III-V semiconductors. However, absolute EL measurements are not yet widely used outside of specific research institutions. This is likely due to technical issues, such as the complexity of the measurement and the short calibration validity period of the standard white lamp used as the reference. These issues must be resolved in order to develop and evaluate multi-junction solar cells made from new materials. We believe that the best solution is to develop absolute EL standard cells.
