Enhancing the Buried Interfacial Interaction to Obtain Homogeneous Halogen‐Phase Distribution for Efficient Wide‐Bandgap Perovskite Solar Cells

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Chinese explanation / 中文解读

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Original abstract

ABSTRACT Wide‐bandgap (WBG) perovskite solar cells (PSCs) are promising for tandem photovoltaic applications, yet they often suffer from inhomogeneous halogen‐phase distribution and interfacial recombination losses. This work introduces a novel self‐assembled monolayer (SAM) hole‐transport material, MeS‐2PACz, engineered with a methylthio (‐SCH 3 ) group to strengthen the buried interfacial interaction in inverted p‐i‐n structured WBG PSCs (∼1.68 eV). Density functional theory (DFT) calculations reveal that the sulfur atom in MeS‐2PACz exhibits a stronger dipole moment and higher adsorption energy with the perovskite, facilitating robust S‐Pb coordination with undercoordinated Pb 2+ ions. This interaction effectively passivates interface defects, reducing the trap density from 1.07 × 10 16 to 8.25 × 10 15 cm −3 , which is lower than that of MeO‐2PACz. Crucially, MeS‐2PACz demonstrates nearly equal binding energies with PbI 2 and PbBr 2 , promoting synchronous crystallization and a homogeneous halogen‐phase distribution. Consequently, perovskite films on MeS‐2PACz show larger grain size, improved crystallinity, and enhanced charge extraction. The champion device based on MeS‐2PACz achieves a power conversion efficiency (PCE) of 22.83%. Furthermore, the unencapsulated devices retain over 90% of their initial PCE after 1500 h under dark‐state storage in a nitrogen atmosphere, demonstrating superior stability. This molecular engineering of the SAM provides a viable pathway toward high‐performance and stable WBG PSCs.

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