摘要
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/PbI_(2)) 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 × 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.
基金
supported by the National Key Research and Development Program of China(2018YFB1500104)
the Technological Innovation Key Project of Guangdong Province(skjtdzxrwqd2018005)
the National Natural Science Foundation of China(U20A20245)。
