Nanoparticle Wetting Agent for Gas Stream-Assisted Blade-Coated Inverted Perovskite Solar Cells and Modules

Lab-scale perovskite solar cells (PSCs) have recently reached power conversion efficiencies (PCEs) of up to 25.2 %. However, a reliable transfer of solution processing from spin coating to scalable printing techniques and a homogeneous deposition on large substrate sizes is challenging also caused by dewetting of the perovskite precursor solution on highly hydrophobic subjacent materials. In this work, we report the utilization of blade coated non-conductive silicon oxide (SiO2) nanoparticles (NPs) as wetting agent for the precursor solution to enable the deposition of a homogeneous perovskite layer on the non-wetting hole transport layer (HTL). The NPs enhance the HTL surface energy, thus, wetting and homogeneous spreading of the precursor solution is strongly improved so that pinholes in the perovskite layer are avoided. In addition, we apply this concept for the first time for gas stream-assisted blade coating of PSCs and modules in the inverted (p-i-n) device architecture with Poly(triaryl amine) (PTAA) as HTL on large-area substrates. In order to prevent void formation at the HTL interface of gas stream-assisted blade coated perovskite layers, the effect of blending small amounts of lead chloride (PbCl2) in the perovskite precursor solution is investigated, which also improves reproducibility and device performance. Following these optimizations, blade coated PSCs with 0.24 cm2 active area achieve up to 17.9 % PCE. Furthermore, to prove scalability, we show enlarged substrates of up to 9×9 cm2 and analyze the homogeneity of the perovskite layer in blade coating direction. Moreover, by implementing the blade coated NP wetting agent, we fabricate large-area modules with a maximum PCE of 9.3 % on 49.60 cm2 aperture area. This represents a further important step bringing solution-processed inverted PSCs closer to application