Interleaving Self-Assembled Monolayers for Efficient and Stable Wide-Bandgap Perovskite Solar Cells and Modules.

Abstract

Self-assembled monolayers (SAMs) are widely used as hole-selective contacts in inverted wide-bandgap (WBG) perovskite solar cells (PSCs). However, incomplete SAM coverage and non-uniform interfacial contact of the SAMs/absorber induce recombination losses and interfacial degradation. Herein, we introduce carbohydrazide (CBH) as an interfacial modifier by interleaving it with SAMs to remedy their uncovered and weakly contacted interfacial regions. The CBH treatment improves interfacial uniformity and strengthens hole extraction, primarily through its dipolar nature and favorable interactions with the perovskite surface. This enables a reduced interfacial defect density and substantially extended interfacial stability. As a result, the optimized WBG perovskite single-junction device achieves a top power conversion efficiency (PCE) of 20.51% (19.56% for control), accompanied by a high open-circuit voltage of 1.355 V. Extending this approach to tandem architectures, its two-terminal all-perovskite tandem solar cell and monolithic mini-module reach impressive PCEs of 29.35% and 23.41% (20.07 cm2), respectively. Both single-junction and tandem devices exhibit pronouncedly improved operational stability. This work provides an innovative and effective strategy to address SAM-related buried interfacial challenges for inverted WBG PSCs.