[14a-A402-1~9] 12.5 有機太陽電池

▲ [14a-A402-5] [Young Scientist Presentation Award Speech] Lead-free tin-germanium (SnGe) halide perovskite solar cells with more than 10 % efficiencies

〇Muhammad Akmal Kamarudin¹、Daisuke Hirotani²、Kengo Hamada²、Kohei Nishimura¹、Shen Qing¹、Satoshi Iikubo²、Takashi Minemoto³、Kenji Yoshino⁴、Shuzi Hayase¹ (1.Univ. of Electro-Com、2.Kyushu Inst. Of Tech、3.Ritsumeikan Univ、4.Univ. of Miyazaki)

キーワード：lead-free, tin-germanium halide perovskites, surface passivation

Lead-free tin perovskite solar cells (PSCs) show the most promise to replace the more toxic lead-based perovskite solar cells. However, the efficiency is significantly less than that of lead-based PSCs as a result of low open-circuit voltage (V_OC). This is due to the tendency of Sn²⁺ to oxidize into Sn⁴⁺ in the presence of air together with the formation of defects and traps caused by the fast crystallization of tin perovskite materials. Here, post-treatment of the tin perovskite layer with edamine Lewis base to suppress the recombination reaction in tin halide PSCs results in efficiencies higher than 10%, which is the highest reported efficiency to date for pure tin halide PSCs. Larger crystal sizes are obtained with EDA post-treatment and the V_OC improved by as much as 0.1 V at an optimum EDA concentration. The X-ray photoelectron spectroscopy data suggest that the recombination reaction mainly originates from the nonstoichiometric Sn:I ratio in addition to the large Sn⁴⁺:Sn²⁺ ratio. The amine group in edamine bonded to the undercoordinated tin, passivating the dangling bonds and defects, resulting in suppressed charge carrier recombination. Simultaneously, charge carrier injection into electron transport layer has also been improved upon surface passivation with EDA as revealed by transient absorption spectroscopy study. This work provides an evident that the surface recombination also needs to be addressed especially in the case of tin perovskite solar cells in order to achieve better device performance.