04 March, 2021
For the commercialization of perovskite solar cells, high-quality and large-scale perovskite films are required. Slot-die coating is a highly promising scalable method. However, the power conversion efficiencies (PCEs) of slot-die PSCs still lag behind their spin-coating counterparts because of the low-quality films caused by the high-speed process.
Figure. SEM top-view images of the pristine and KSCN modified perovskite thin films deposited by slot-die coating.
In this work, simply using potassium thiocyanate (KSCN) as additives, the quality of the slot-die films is improved greatly. The grain size is dramatically improved to ~11 μm, which is top-level for perovskite polycrystalline films. The polycrystalline methylammonium lead triiodide (MAPbI3) films show single-crystal-level parameters such as 1.89 μs lifetime, 136.65±31.52 cm2/(V∙s) mobility, and 25.15±3.55 μm diffusion length. Thanks to their excellent photoelectric parameters, ~2 μm absorber layer can be occupied for excellent near-bandage absorption. As a result, slot-die planar inverted MAPbI3 PSCs have an average and a maximum PCE of 20.14% and 21.38%, respectively, which is among the highest reported values for slot-die coated PSCs and top-level for MAPbI3-based PSCs.
Figure. J-V characteristics and the schematics of the devices.
Notably, paving the way to further industrialization, all layers of our PSCs are fabricated by large-scale methods, including blade coating, slot-die coating, and thermal evaporation. On the films, the J-V curves of 9 pixels of PSCs located along the slot-die axis, covering a length of 7.5 cm, have a variance in PCE of 0.0023 which is little to be ignored.
Figure. The J-V characteristics of various devices at the slot-die head scan direction.
This work proves that KSCN as an additive is very potential to improve the performance of PSCs and the slot-die method is applicable in further industrialization of PSCs.Reference: Xu, F. et al. Potassium Thiocyanate‐Assisted Enhancement of Slot‐Die‐Coated Perovskite Films for High‐Performance Solar Cells. Small Science 2000044, 2000044 (2021).