Highly enhanced long time stability of perovskite solar cells by involving a hydrophobic hole modification layer

Recently, much progress has been achieved in the lab prototype perovskite solar cells (PSCs), however, the challenging toward the commercial production of PSCs still remains, which is their low stability due to the inherent moisture sensitivity of the perovskite photoactive layer. In this work, a hydrophobic hole modification layer, zinc phthalocyanine (ZnPc), is introduced to the typical planer hetero-junction (PHJ) structure to improve the device performance and prevent moisture. The ZnPc based devices show an improved power conversion efficiency ( PCE ) of 16.8% compared to 15.1% for the unmodified devices, and highly enhanced long-term stability (91% of initial PCE remains after 2400   h), which is the best report for PSCs in ambient environment without sealing. In addition, pulsed laser deposition (PLD) technique is used to prepare electron collection layer Nb-doped TiOx in PSC fabrication process. Devices with large area (225   mm 2 ) and flexibility were also fabricated in this study to demonstrate the potential practical application of this strategy. This work paves a way for the developments of PSCs with long-term stability and demonstrates a strategy toward practical applications for PSCs.