"Coffee ring" controlment in spray prepared >19% efficiency Cs0.19FA0.81PbI2.5Br0.5 perovskite solar cells

作者：Yu, Xinxin; Li, Jing; Mo, Yanping; Xiang, Tianxing; Ku, Zhiliang; Huang, Fuzhi; Long, Fei; Peng, Yong^*; Cheng, Yi-Bing

来源：Journal of Energy Chemistry, 2022, 67: 1-8.

DOI：10.1016/j.jechem.2021.09.032

• Cs(0.19)FA(0.81)PbI(2.5)Br(0.5) perovskite solar cells
• Spray coating
• Coffee ring effect
• Reaction-dependent regulating strategy

Achieving high-quality perovskite films with uniform morphology and homogeneous crystallinity is challenging owing to the coffee ring effect (CRE) in the spray-coating technologies. In this study, an evaporation/spray-coating two-step deposition method is used to fabricate Cs(0.19)FA(0.81)PbI(2.5)Br(0.5) light harvesters for perovskite solar cells (PSCs). Considering the solid-liquid reaction, we establish a reaction-dependent regulating strategy that inhibits CRE successfully and prepare a high-quality perovskite layer, wherein the solvent for the FAI/Br solution during the spraying process is changed from isopropanol to n-butyl alcohol (NBA). The retarded-drying-enhanced spreading of the NBA solution inhibits contact line pinning to suppress the capillary flows and increases the reaction between metal halides (CsI/PbI2) and organic salts (FAI/Br), which result in a reduction in the accumulation of solutes in the periphery effectively inhibiting CRE. Consequently, we obtain a high performance Cs(0.19)FA(0.81)PbI(2.5)Br(0.5) PSC with a power conversion efficiency (PCE) of 19.17%. An enlarged perovskite film (10 x 10 cm(2)) containing 40 sub-cells is prepared. The average PCE of these devices is 18.33 +/- 0.56%, proving the reliability of the "coffee ring" regulating strategy. This study provides an effective approach for CRE controlment in spraying technology to achieve high repeatability devices with good performance.

• 单位
  y; 武汉理工大学; 桂林理工大学