Rational design of methylthio-based self-assembled molecule for buried interface engineering in perovskite solar cells

Abstract

Self-assembled monolayers (SAMs) have been successfully designed and adopted in the field of inverted perovskite solar cells (PSCs), in which molecular introduction could optimize the buried interface of perovskite films. Compared to the typical [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), the multifunctional SAMs with methylthio (MeS) group were introduced to simultaneously modulate perovskite crystallization kinetics and passivate the interface defects. Using in-situ photoluminescence (PL) spectroscopy, it is well demonstrated that the strong interaction between MeS and uncoordinated Pb2+ significantly retards the nucleation kinetics and promotes grain ripening, leading to 12% increase of grain size at the buried interface. Meanwhile, the carrier lifetime measured by transient absorption (TA) spectroscopy also increased from 711.97 ps to 1832.72 ps. As a result, the target devices exhibit an effective power conversion efficiency (PCE) promotion from 22.10% to 25.21%, accompanied by an enhanced open-circuit voltage (VOC) from 1.08 to 1.17 V. © 2025 Elsevier B.V.