Merged interface construction toward ultra-low Voc loss in inverted two-dimensional Dion-Jacobson perovskite solar cells with efficiency over 18%

An optimized interface between a perovskite and a charge transport layer with full contact and low defect density favors an improvement in performance of perovskite solar cells (PVSCs). However, few works have been reported on constructing an interface for efficient charge transport and low energy loss in 2D Dion-Jacobson (DJ) PVSCs with an inverted structure. Herein, a deposition process combining pre-annealing and merged annealing (PMA) was demonstrated to be effective in constructing a merged interface between the layers of an electron transport material, PC61BM, and DJ perovskite (3AMP)(MA(0.75)FA(0.25))(3)Pb4I13, which promotes perovskite/PC61BM contact and thus improves defect passivation and charge transport. A high V-oc (1.24 V) with ultra-low energy loss (0.35 eV) is achieved because of the decreased defect density. A PMA-based device with a structure of ITO/(NiOx/PTAA)/perovskite/PC61BM/BCP/Ag exhibits a highest PCE of 18.67%, which is the highest value among the 2D DJ PVSCs with an inverted structure. The device retains 90% of its initial PCE after storage in air with a humidity of 45 +/- 5% for 60 days or in an 85 degrees C N-2 atmosphere for 480 h, and remains unchanged in 50 cycles of thermal cycling measurements. This work provides an effective approach towards 2D DJ PVSCs with both high efficiency and high moisture and thermal stability.