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Dual Role of Self-Assembled Monolayers: Interfacial Dipoles and Charge Tunneling in High-Efficiency Inverted Perovskite Solar Cells
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DOI:10.1021/acsenergylett.6c01335.png)
Abstract
En 中文
High efficiencies of inverted perovskite solar cells that use self-assembled monolayers (SAMs) are closely tied to unresolved interfacial mechanisms. This study decouples the dual functions of carbazole-based SAMs featuring tailored alkyl chains. Kelvin probe force microscopy confirms that an interfacial dipole field, enhanced by longer chains, suppresses recombination and increases open-circuit voltage (VOC). In parallel, conductive atomic force microscopy shows that the alkyl chain itself serves as a tunneling barrier. Longer chains impede hole extraction, resulting in saturated tunneling current and a consequent decline in the maximum power point voltage (Vmax). This inherent trade-off defines the dual roles of SAMs: enhancing VOC through the dipole effect while mediating charge transfer via tunneling. An optimal balance is achieved with a four-carbon alkyl chain (4PACz), which combines efficient tunneling with strong passivation. Our findings provide a new design principle that co-optimization of dipole strength and tunneling probability is essential for developing high-performance SAMs.
Keywords:
Alkyls
Molecular structure
Self-assembled monolayers
Solar cells
Tunneling
Journal
IF:
18.2
Papers:
5.2K
Citations:
6.6W
