Anti-solvent engineering for efficient and stable perovskite solar cells with preferentially orientated 2-dimensional/3-dimensional heterojunctions

Abstract

To date, the trade-off between passivation and transport in 2-dimensional (2D)/3-dimensional (3D) perovskite heterojunctions has been a challenge in simultaneously maximizing the open-circuit voltage (V_OC) and fill factor (FF). Herein, we realized high-quality and preferentially orientated 2D/3D perovskites via anti-solvent engineering. We systematically studied different anti-solvents and put forward a hybrid anti-solvent strategy, which provides better balance between their extracting ability and volatility. This is helpful to eliminate granular grains. To obtain preferentially orientated 2D/3D perovskites, 4-methoxy-phenethylammonium iodide (4-MeO-PEAI) and n-hexylammonium iodide (n-HeXAI) were added to hybrid anti-solvents, which promoted the (001) facet out-of-plane orientation of perovskite films and formed a thin but highly uniform 2D capping layer. We also discovered that longer-chain single ammonium salts tend to enhance the preferential orientation of perovskites but double ammonium salts do not. The preferentially orientated 2D/3D perovskites facilitated the efficient transport of photogenerated carriers in the bulk and on the surface. As a result, an impressive V_OC of 1.218 V and efficiency of 26.02% (certified 25.42% with an FF value of 85.85%) were achieved, which are some of the highest certified FF and V_OC × FF values of the Shockley–Queisser limit (90.6%). Meanwhile, the strategy also achieved an efficiency of 22.59% for the mini-module (active area of 12.4 cm²). The optimized devices maintained 87.6% of the initial efficiency for 7000 h under ISOS-D-1 conditions and 97.8% efficiency for 2100 h under ISOS-L-2 conditions with a linear fitting extrapolation to a T₈₀ of 10 467 h.