Recently, professorLitao Sun’s team, from the southeast university school of electronic science & engineering, made important progress on In situ photoelectric device research. The result with In situ interface engineering for probing the limit of quantum dot photovoltaic devices was published on the latest issue of Nature Nanotechnology with the impact factor of 33.4. Southeast university is the first completed unit and Professor Litao Sun is the corresponding author. Hui Dong as a doctoral studentand Feng Xu as a young teacher in our school are the co-first authors.
Energy is an important material guarantee to meet the basic needs of human society and sustainable development. Due to the non-reproducibility of fossil energy and the global attention to the greenhouse effect, the effective use of solar energy is becoming the primary choice in most countries. Quantum dot solar cells have many advantages, such as low preparation cost, adjustable band gap and high theoretical conversion efficiency, and thus have great application potential in the field of solar energy conversion. However, the photoelectric conversion efficiency is still far lower than the theoretical conversion efficiency. How to explore the basic mechanism of low efficiency at the micro scale and provide guidance for the design of solar cells with high conversion efficiency? This problem poses a theoretical and technical challenge to modern research methods.
Figure. 1 (a) Schematic diagram of the construction of quantum dot heterojunction solar cell inside TEM; (b) TEM images of single nanowires/ quantum dot heterojunction cells and (c) Atomic scale high-resolution TEM images and (d) photocurrent response under dark and light (pAlevel).
To solve this problem, ProfessorLitao Sun’s team has developed a new type of in situ photoelectric technique inside microscopyindependently. Based on this technique, the smallest scale quantum dots heterojunction solar cell structure in the world (including only single nanowires, quantum dots and the electrode, as shown in Figure 1 a and 1 b) was constructed in the current status. Under the action of light field, atomic scale resolution of material structure (as shown in Figure 1 c) and in situ measurement of photocurrent device at the precision of picoampere level (as shown in Figure 1 d) can be realized at the same time. The conversion efficiency of the cell is greatly improved by adjusting the interface area, which reveals that the interface engineering plays an important role on improving the conversion efficiency of the solar cell. The research results are helpful to better understand the internal mechanism of high conversion efficiency of quantum dot heterojunction solar cells and promote the research and optimization design of high conversion efficiency solar cells and the other related photoelectric devices. At the same time, the results provide the best experimental conditions for the direct study of nanoscale devices and promote the rapid development of in situ electron microscopy.The above work benefits from the long-term support of our university and emphasis on the basic frontier research and international academic exchanges. It is the result of the integration of electronic, materials, physics, chemistry and other subjects. Professor Ze Zhang in Zhe Jiang University and Professor XianfengDuan in University of California Los Angeles are co-corresponding authors and Professor Ziqi Sun in Queensland University of Technology in Australia is the co-first author.The project has been carried more than seven years and was funded by the National key research and development project, National key research and development program, National natural science foundation of China and other projects.
