Noncoplanar multidentate contacts reinforce buried interface for perovskite/silicon tandem solar cells

The buried interface between the self-assembled monolayers (SAMs) and the perovskite plays a critical role in device performance and stability in inverted perovskite solar cells (PSCs). However, severe desorption and agglomeration of self-assembled molecules lead to interfacial losses and shorten device longevity. Herein, we design a molecule, 5,5',5″-(nitrilotri-4,1-phenylene)tris[2-thiophenecarboxylic acid] (TTA) with a noncoplanar molecular configuration and multiple functional groups. The noncoplanar molecular configuration could effectively suppress π-π stacking-induced aggregation and enable more regulated molecular packing. Its thiophene functional unit and tridentate carboxylic anchoring groups enhance interactions with substrates and the upper perovskites, assisted by the noncoplanar configuration, which is confirmed by density functional theory (DFT) calculations. When combined with the commonly used 4-(3,6-dimethyl-9H-carbazol-9-yl)butane-1-phosphonic acid (Me-4PACz), this strategy enables a more homogeneous self-assembled molecular film, improved perovskite crystallinity, and reduced trap density. Consequently, the wide-bandgap (WBG) PSC (∼1.67 electron volts) demonstrates a champion power conversion efficiency (PCE) of 23.7%, with enhanced thermal-cycling and light-soaking stability. In addition, the perovskite/silicon tandem devices based on this strategy achieve a PCE of 33.3% (certified at 33.1%) and demonstrate real-world operational stability of no observed PCE loss after 30 days of outdoor operation.