van der Waals Mixed Valence Tin Oxides for Perovskite Solar Cells as UV-Stable Electron Transport Materials
Sheng Li, Fei Qin, Peng Qi, Shuang Liu, Zhihui Zhang, Deyi Zhang, Chao Liu, Daiyu Li, Jiale Liu, Jianhang Qi, Yue Hu, Yaoguang Rong, Anyi Mei, Hongwei Han
Abstract
Stable electron transport materials (ETMs) with fewer surface defects and proper energy level alignments with halide perovskite active layers are required for efficient perovskite solar cells (PSCs) with long-term durability. Here, two-dimensional van der Waals mixed valence tin oxides Sn2O3 and Sn3O4 are controllably synthesized and applied as ETMs for planar PSCs. The synthesized Sn2O3 and Sn3O4 have size of 5–20 nm and disperse well in water as stable colloids for months. Both Sn2O3 and Sn3O4 exhibit typical n-type semiconductor energy band structures, low trap density, and suitable energy level alignments with halide perovskites. Steady-state power conversion efficiencies (PCEs) of 22.36% and 21.83% are obtained for Sn2O3-based and Sn3O4-based planar PSCs. In addition, the half cells without hole transport materials and back electrodes show good UV-stability with average PCE of 99.0% and 95.7% for Sn2O3-based and Sn3O4-based devices remaining after 1000 h of ultraviolet soaking with an intensity of 70 mW cm–2.