[20a-432-1~12] 12.5 Organic solar cells

▲ [20a-432-4] Realizing high efficiency and air-stable tin-based perovskite solar cells via GeBr₂ doping

〇Akmal Kamarudin¹, Kohei Nishimura¹, Daisuke Hirotani¹, Satoshi Iikubo¹, Qing Shen², Taro Toyoda², Takashi Minemoto³, Kenji Yoshino⁴, Shuzi Hayase¹ (1.Kyushu Inst., 2.Univ. of Electro-Com, 3.Ritsumeikan Univ., 4.Miyazaki Univ.)

Keywords:Tin-based perovskite, Carrier density, Surface passivation

Self-doping of tin-based perovskite materials upon exposure to air as a result of tin oxidation from Sn²⁺ to Sn⁴⁺ increased the charge carrier density of the perovskite material. This increased of charge carrier density result in higher recombination reaction and thus leading to degradation of solar cells over time even in N₂ atmosphere and much so in ambient atmosphere. In this work, we doped the tin-based perovskite material with GeBr₂ to control the charge carrier density and improve the air stability of the solar cells. The performance of GeBr₂-doped perovskite solar cell achieved a high efficiency of 4.2 % compared to 2.9 % for FA_0.75MA_0.25SnI₃ when measured in air. The increased in efficiency comes from the significant increase of short circuit current due to the reduction of charge carrier concentration. The reduction of trap states upon addition of GeBr₂ has also been confirmed by thermally stimulated current measurement. The formation of monolayer GeO₂ reduced the surface oxidation of the perovskite and helped to improve the air stability of the perovskite solar cell.