[9p-S222-1~12] 12.5 Organic solar cells

▼ [9p-S222-6] Trap Landscape and Carrier Dynamics of SnGe Perovskite Solar Cell

〇(P)Chi Huey Ng¹, Kengo Hamada¹, Daisuke Hirotani¹, Satoshi Iikubo¹, Qing Shen², Kenji Yoshino³, Takashi Minemoto⁴, Shuzi Hayase¹ (1.Kyushu Inst. of Tech, 2.Univ. of Electro-Com, 3.Univ. of Miyazaki, 4.Ritsumeikan Univ.)

Keywords:lead free perovskite solar cell, trap density, carrier dynamics

The trap states distribution within the perovskite vicinity is the prime factor causes carrier dynamics inferiority and low photovoltaic performances. Hence, in this work, we emphasizes two important criterions, which are first to investigate the role of SnF2 in suppressing Sn vacancy and secondly, to elucidate the effect of Ge dopant over the trap states and charge transport within the perovskite solar cell, which are revealed through thermally stimulated current (TSC) and its complementary analyses. The suppression of Sn2+ oxidation process is proven through the XPS analysis where the Sn2+/Sn4+ ratio has substantially reduced upon the addition of SnF2. From the viewpoint of trap density, we found that the total trap densities have been significantly reduced from 1.93x1021 cm-3 (without Ge) to 1.80x1017 cm-3 upon the addition of 5 mole% Ge. Interestingly, the FMSGI(5) perovskite exhibits a long charge diffusion length and high mobility of 1 μm and 98.27 cm2V-1s-1, respectively. In addition, the 5 mole% Ge-doped perovskite exhibited long-lived carrier lifetime of 5.04 ns than the perovskite without Ge dopant (average lifetime = 3.46 ns), implies the effectiveness of Ge in passivating the trap states. The SnGe perovskite solar cell exhibits high efficiency of 7.9% with negligible hysteresis effect. This work provides deep intuitive on trap landscape, which is important for the performance enhancement of lead free perovskite solar cells.