[18p-Z20-1~12] 12.5 Organic solar cells

▲ [18p-Z20-9] Inverted CsPbI₂Br Perovskite Solar Cells with Enhanced Efficiency and Stability in Ambient Atmosphere via Formamidinium Incorporation

〇(D)Chen Mengmeng¹, Shahrir Razey S.¹, Kapil Gaurav³, Baranwal Ajay K.¹, Kamarudin Muhammad Akmal¹, Nishimura Kohei¹, Hirotani Daisuke², Shen Qing¹, Hayase Shuzi¹ (1.Univ. Elec.-Communi., 2.Kyushu Inst. of Technology, 3.Tokyo Univ.)

Keywords:Wide-bandgap, CsPbI2Br solar cell, stability

CsPbI₂Br is expected to be a candidate for the top layer of the all perovskite tandem solar cells. However, the perovskite is prone to change the phase from α (black) to δ (yellow) type. In this research, Cs_1-xFA_xPbI₂Br perovskites were fabricated in ambient atmosphere and their properties immediately after fabrication and the phase stability were investigated. The quality of the perovskite films was enhanced and the trap density was reduced after the incorporation of the FA cations. The phase stability of the Cs_1-xFA_xPbI₂Br perovskite was effectively enhanced. Consequently, the highest power conversion efficiency of 12.28% with open-circuit voltage (Voc) of 1.09 V, current intensity (Jsc) of 15.65 mA cm^-2, and fill factor of 72% in the planar solar cell based on Cs_0.7FA_0.3PbI₂Br perovskite was achieved. The band gap was optimized to be about 1.82 eV suitable for all perovskite tandem top layer. Most importantly, all the photovoltaic parameters of Cs_0.7FA_0.3PbI₂Br perovskite solar cells showed ignorable decay after 2 months’ measurement in ambient atmosphere with the presence of air and humidity without encapsulation.