Surface science research on metal halide perovskite materials for realization of high-performance solar cells

Challenges associated with energy supply and global warming have raised public awareness of the need to develop renewable green energy sources. Solar energy is the most abundant form of renewable energy available, and its effective utilization is critical to sustainable clean energy, reducing CO2 emission and therefore mitigating the negative impact of global climate changes. As such, tremendous effort has been directed to research on solar cell materials and devices. My research team at OIST has been using a surface science approach to studying the structure-property relationship in metal halide perovskite materials, which have shown great potential in solar cell applications. Furthermore, on the basis of these surface science findings, we are developing innovative solar cell technologies.

Using surface science techniques and advanced characterization tools such as Scanning Tunneling Microscopy (STM) and Photoemission Spectroscopy (PES), we have determined the surface structures of a wide range of metal halide perovskite materials at the atomic scale, visualized atomic scale surface defects and their dynamic behaviors, and revealed the importance of chlorine incorporation on perovskite surface stability. Furthermore, we have applied such fundamental understanding obtained from our surface science studies into solar cell device applications. For instance, we developed a holistic approach to interface stabilization in fabricating large-area perovskite solar modules, and the resulted modules with a designated area of 22.4 cm2 reached an efficiency of 16.6% and operational stability over 2000 hours.

A more comprehensive understanding of perovskite materials at the atomic scale will provide crucial rational design guidelines for syntheses of novel perovskite materials, new interface engineering strategies, and innovative solar cell device architectures, which is expected to accelerate commercialization of perovskite solar technologies.