[19a-432-1~12] 12.5 Organic solar cells

▼ [19a-432-7] High Performance Lead-Reduced Mixed-Cation Perovskite Solar Cells

〇(B)Yiying Li¹, ShunHsiang Chan¹, MingChung Wu¹ (1.Chang Gung Univ.)

Keywords:mixed-cation perovskite solar cells, metal-doped perovskite, lead-reduced perovskite solar cells

Organic-inorganic lead halide perovskite solar cells (PSCs) have attracted tremendous interest in last six years with rapid progress in power conversion efficiencies (PCE) from 0.3% to 3.8% in 2006-2009 to the present record of 22.7%. Tuning composition of lead halide perovskite by introducing mixed cation have stabilized the solution process to make large uniform grains, which ultimately led to high efficiency and stability of solar cell. Using formamidinium lead triiodide (FAPbI₃) instead of methylammonium lead triiodide (MAPbI₃) is advantageous due to the reduced bandgap, which is closer to the single-junction optimum and would thus allow for higher solar light harvesting efficiency. Many types of metal ions were used to replace the Pb²⁺ to synthesize various metal-doped perovskite compounds, including Bi³⁺, Sn²⁺, Ca²⁺, Cu²⁺, Na⁺, K⁺ and Ba²⁺. Among these metal ions, Ba-doped perovskite structured materials can replace the lead without decreasing the photovoltaic performance. In this study, we combine mixed-cation with Ba-doped perovskite to fabricate high performance lead-reduced PSCs.
In summary, we try to increase the device performance by adding FA⁺ to MA⁺. As the concentration of MA_0.8FA_0.2 PbI_3-yCl_y increases, the PCE will increase, and 1.7 M MA_0.8FA_0.2PbI_3-yCl_y gives the best photovoltaic performance. To get high performance lead-reduced PSCs, we combine Ba²⁺ substitution of Pb²⁺ with 1.7 M MA_0.8FA_0.2 PbI_3-yCl_y. When 5.0 mol% Ba²⁺ is doped, the best MA_0.8FA_0.2Ba_0.05Pb_0.95I_3-yCl_y device gives V_oc of 1.06 V, J_sc of 22.3 mA/cm², FF of 70.4% and PCE of 16.6%.