Functional interface engineering using methoxy-terminated monolayers for efficient 2D perovskite solar cells

초록

The performance of quasi two-dimensional (Q-2D) Ruddlesden-Popper perovskite solar cells (PSCs) is critically influenced by the choice of the hole transport layer (HTL). This study systematically evaluates self-assembled monolayer (SAM)-based HTLs as alternatives to the conventional poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) HTL. Among the SAMs examined in this study, [2-(3,6-dimethoxy-9H-car-bazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), with a methoxy functional group, demonstrated superior performance, achieving a higher power conversion efficiency (15.07 %) compared to that (8.69 %) of PEDOT:PSS. The methoxy group in MeO-2PACz enhanced the crystallinity and vertical alignment of the Q-2D perovskite layer, reducing trap states and grain boundaries. The strong interactions between MeO-2PACz and uncoordinated Pb2+ ions effectively passivated surface defects, facilitating efficient charge transport. Additionally, MeO-2PACz-based devices demonstrated superior long-term stability, retaining 70 % of their initial efficiency after 400 h under ambient conditions without encapsulation. These findings highlight the promising potential of tailored SAMs for improving the efficiency and stability of Q-2D-PSCs, providing a pathway toward scalable applications in photovoltaic technologies.

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