Two-dimensional Ruddlesden-Popper (2DRP) phase perovskites have excellent long-term environmental and structure stability. However, the efficiency of 2DRP perovskite solar cells (PSCs) still lags behind that of their 3D counterparts due to the large exciton binding energy between the large-volume organic spacer and the inorganic plate compared to their 3D analogs.
To address this issue, researchers from China's Northwestern Polytechnical University and Xijing University have used a thin layer of self-assembled monolayer material between the transporting layer and the perovskite film for efficient and stable 2DRP-based PSCs.
The thin layer of self-assembled monolayer material 2PACz-Br was employed between PEDOT: PSS layer and perovskite layer (β-GUA)2(FA)4Pb5I16 for stable and efficient 2DRP PSCs. It was found that the introduction of 2PACz-Br before the perovskite film promoted higher affinity of 2PACz-Br film with solvent DMAc, resulting in better crystallinity and film quality. 2PACz-Br effectively reduced the defect density and restrained non-radiative recombination in perovskite film, and promoted more matched energy levels between the perovskite layer and the charge-carrier transport layer.
Benefiting from the conducive collection and transmission of charge carriers, the 2PACz-Br-based 2DRP (β-GUA)2(FA)4Pb5I16 device realized an impressive PCE of 19.13 %, higher than that of the device without 2PACz-Br modification (PCE = 17.70 %). Moreover, 2PACz-Br-based 2DRP PSCs performed superior stability compared to their control counterparts.
The team stated that this study paves the way to efficient and stable 2DRP-based PSCs by inserting a multifunctional self-assembled monolayer. The scientists anticipate that the proposed interfacial engineering in this work will open an efficient avenue for achieving efficient and stable 2D PSCs.
