[21a-W531-1~11] 12.5 Organic solar cells

▲ [21a-W531-10] Exciton dynamics in CH₃NH₃PbI₃ single crystals

〇(P)Le Quang Phuong^1,2, Yumi Nakaike¹, Atsushi Wakamiya¹, Yoshihiko Kanemitsu^1,2 (1.Kyoto University, 2.JST-CREST)

Keywords:Methylammonium lead iodide,single crystals,excitons

Although the power conversion efficiency (PCE) of solar cells developed based on methylamonium lead iodide perovskite CH₃NH₃PbI₃ (MAPbI₃) is approaching a value of over 20%, which is comparable to the highest PCEs of inorganic semiconductor thin-film solar cells, a further improvement can be proceeded if more insights into the photophysics of MAPbI₃ are obtained. Therefore, many studies have been done to explore the fundamental properties of MAPbI₃. Despite the strong efforts, there are still many issues remaining unclear. The exciton binding energy of orthorhombic-phase MAPbI₃ at low temperatures is approximated to be in a range of 16 to 63 meV. However, so far there is no experimental evidence showing clearly the existences of excitons and biexcitons. In thin-film samples, the tetragonal phase maintains even at temperatures below the phase transition, and the ultrafast carrier transfer from the orthorhombic phase to the tetragonal phase is likely to prevent the formation of excitons in the major orthorhombic phase. In order to gain understanding of the basic physics of excitons and biexcitons in MAPbI₃, works on single crystals have to be performed.