The 67th JSAP Spring Meeting 2020

Presentation information

Oral presentation

12 Organic Molecules and Bioelectronics » 12.5 Organic solar cells

[14a-A402-1~9] 12.5 Organic solar cells

Sat. Mar 14, 2020 9:00 AM - 11:45 AM A402 (6-402)

Kazuhiro Marumoto(Univ. of Tsukuba), Shuji Hayase(Kyushu Inst. of Tech.)

10:00 AM - 10:15 AM

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

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)

Keywords: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 (VOC). 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 VOC 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.