Binary Additive Engineering Enables Efficient Perovskite Solar Cells via Spray-Coating in Air

Abstract

Spray-coating as a high throughput and low-cost deposition process endows perovskite solar cell (PSC) devices the possibility of large-scale production, while the low device efficiency due to poor and uncontrolled film quality impedes the commercialization process of PSCs. Herein, we demonstrate a binary additive engineering strategy to achieve a device efficiency of 18.2% with minor hysteresis by spray-coating the (FAPbI 3 ) x (MAPbBr 3 ) 1−x hybrid perovskite in air. The spray-coated perovskite films have a hierarchical structure that is composed of large grains of over 100 μm and small grains of around 400 nm. The incorporation of L-α-phosphatidylcholine additive in the perovskite precursor improves crystallinity, narrows grain boundaries between large grains, and passivates FA + /MA + vacancies, consequently increasing light absorption and reducing trap-assisted charge recombination to improve efficiency. The addition of KI additive increases the large-grain size and passivates defects, thereby reducing hysteresis as well as further enhancing efficiency. This work introduces a facile binary additive approach to fabricate high efficiency, one-step spray-coated PSCs in ambient conditions.

Recent Developments in Upscalable Printing Techniques for Perovskite Solar Cells

“…[147] Using the same substrate heating and gas quenching method, Fievez et al reported the slot-die coating of methyl ammoniumfree Cs 0.16 FA 0.84 Pb(I 0.88 Br 0.12 ) 3 perovskite film for the fabrication of n-i-p structured PSCs which delivered a PCE of 18% over 0.09 cm 2 active-area device. [149] Moreover, optimization of print- [159] Copyright 2021, American Chemical Society. c) J-V curves of the fully spray-coated PSCs (ITO glass/SnO 2 /perovskite/spiro-OMeTAD/Ag).…”

“…Reproduced with permission. [ 159 ] Copyright 2021, American Chemical Society. c) J–V curves of the fully spray‐coated PSCs (ITO glass/SnO 2 /perovskite/spiro‐OMeTAD/Ag).…”

“…By successfully adding L‐ α ‐phosphatidylcholine and KI into the perovskite ink, they found that the L‐ α ‐phosphatidylcholine narrowed the grain boundary, and KI further reduced the grain boundaries and passivated the defects, which significantly improved the PCE (18.2%) (Figure 5b). [ 159 ] It is very challenging to achieve high‐quality perovskite films with uniform morphology and homogeneous crystallinity due to the coffee ring effect in the spray‐coating process. To overcome this issue, a two‐step process combining evaporation and spray coating has been found to be very effective in depositing Cs 0.19 FA 0.81 PbI 2.5 Br 0.5 perovskite films.…”

“…b) J-V curves of the spray-coated PSCs (ITO glass/SnO 2 /perovskite/spiro-OMeTAD/Ag) with L-𝛼-phosphatidylcholine and KI additives for the perovskite ink. Reproduced with permission [159]. Copyright 2021, American Chemical Society.…”

Gas‐Assisted Spray Coating of Perovskite Solar Cells Incorporating Sprayed Self‐Assembled Monolayers

“…[ 70 ] However, to trigger nucleation during or after spray coating, researchers have also used an antisolvent bath method, [ 29,71 ] although the scalability of this processes is limited by the use of significant quantities of solvent that becomes gradually “contaminated” during any device run. Alternative approaches to induce supersaturation include thermal annealing, [ 72 ] vacuum‐assisted solution processing, [ 73 ] hot‐air blowing, [ 74 ] and plasma‐treatments. [ 22 ] Here, we investigate a GASP protocol in which an ambient temperature nitrogen gas‐jet from an air‐knife is blown at a surface that has been spray‐cast with a perovskite precursor solution, with the evaporation of the volatile casting‐solvent inducing supersaturation.…”