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

Optimized interface between perovskite and the charge transport layer with full contact and low defect density favored the performance improvement of perovskite solar cells (PVSCs). However, few works have been reported on constructing interface for efficient charge transport and low energy loss in 2D Dion-Jacobson (DJ) PVSCs with inverted structure. Here in this work, a deposition process combining pre-annealing and merged annealing (PMA) was demonstrated effective in constructing a merged interface between the layers of electron transport material PC61BM and DJ perovskite (3AMP)(MA0.75FA0.25)3Pb4I13, which promotes perovskite/ PC61BM contact and thus improves defect passivation and charge transport. A high Voc (1.24 V) with ultra-low energy loss (0.35 eV) is achieved because of the decreased defect density. The PMA-based device with 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 inverted structure. The device retains 90% of initial PCE after storage in air with a humidity of 45 ± 5% for 60 days or in 85oC N2 atmosphere for 480 hours, and remains unchanged in 50 times of thermal cycling measurements. This work provides an effective approach towards 2D DJ PVSCs with both high efficiency and high moisture and thermal stability.