Dilute Nitride GaNAsP for High Efficiency Multiband Solar Cells

技术：本研究项目旨在通过研究一种多带材料，即带有中间带的半导体，来提高太阳能电池的功率转换效率。这种材料实际上有三个吸收带，一个单结可能相当于一个更复杂但高效率的三结太阳能电池。这种材料的生长和加工，以及对多波段太阳能电池的理解和建模，都是一个重大挑战。这个项目的重点是一类特殊材料的材料生长和加工，稀氮化物GaNAsP有一个中间带，这样电子就可以被带隙下的光子吸收，被激发到中间带，并进入提供电流的导带。这些带隙以下的光激发是对带隙以上光子的吸收，从而直接激发从价带到导带的电子。PI、他的学生和国家可再生能源实验室的合作者将研究生长、加工和表征的基本方面，目的是更好地了解基础材料科学，并优化用于太阳能电池应用的多波段材料。与单频太阳能电池相比，该方法包括制造和测试。预计结果是对这种多波段半导体的物理性质有更多的了解，从而推动该领域的整体发展，并提高太阳能电池的性能。非技术性：这个项目解决了材料科学的一个具有高度技术相关性的主题领域的基础研究问题。高效太阳能光伏电池通过更高效的电能产生，对经济和人类生活具有广泛的潜在影响。与单结和多结太阳能电池相比，本项目研究的多波段太阳能电池可以提供明显更高的效率和更低的成本。研究活动将促进学生在新型化合物半导体的生长和表征、太阳能电池原型器件设计和制造方面的跨学科培训。本科生也将参与研究项目；他们将从各种来源招募，包括为低收入学生和/或代表性不足的少数族裔服务的麦克奈尔计划。本科生的活动将包括高级特征，如原子力显微镜，并参加加州大学圣地亚哥分校的各种本科生研究会议。此外，PI是COSMOS(加州州立数学与科学暑期学校)寄宿暑期项目的负责人，该项目面向150名高中生。这一研究项目的成果可以纳入课程，并通过COSMOS的教师伙伴计划推广到高中。

Technical: This research project aims to improve the power conversion efficiency of solar cells by investigating a multiband material, a semiconductor with an intermediate band. Such a material has effectively three absorption bands and a single junction could be equivalent to a more complicated, but high-efficiency, three-junction solar cell. The growth and processing of such a material is a major challenge, along with understanding and modeling of a multiband solar cell. The emphasis of this project is on materials growth and processing of a particular class of materials, dilute nitride GaNAsP, which has an intermediate band so that electrons can be absorbed by below-bandgap photons, be excited to the intermediate band, and on to the conduction band providing current. These below-bandgap photo-excitations are in addition to the absorption of above-bandgap photons to excite electrons from the valence band to the conduction band directly. The PI, his students and collaborators at the National Renewable Energy Laboratory will study fundamental aspects of the growth, processing and characterization, with the aim toward greater understanding of fundamental materials science and optimization of the multiband material for solar cell applications. The approach includes fabrication and testing, in comparison with single-band solar cells. Greater understanding of the physical properties of such multiband semiconductors is expected as an outcome, advancing the field generally, and the performance of solar cells. Non-technical: This project addresses basic research issues in a topical area of materials science with high technological relevance. High-efficiency solar photovoltaic cells have broad potential impact on economy and human life through more efficient electrical energy generation. Compared to single-junction and multijunction solar cells, the multiband solar cells investigated in this project could provide significantly higher efficiency and lower cost. The research activities will promote interdisciplinary training for students in growth and characterization of novel compound semiconductors, prototype solar cell device design, and fabrication. Undergraduate students will also participate in the research project; they will be recruited from various sources, including the McNair Program, which serves low-income students and/or underrepresented minorities. The undergraduate students' activities will include advanced characterizations, such as atomic force microscopy, and participation in various undergraduate research conferences at UCSD. Additionally, the PI is the director of the COSMOS (California State Summer School for Mathematics and Science) residential summer program for 150 high school students. The results of this research project can be incorporated into the curriculum and extend to the high schools through the Teacher Fellow program of COSMOS.