Amphoteric coplanar conjugated molecules enabling efficient and stable perovskite/silicon tandem solar cells

The perovskite/silicon tandem solar cells (TSCs) offers a state-of-the-art solution for achieving unparalleled efficiency and cost-effectiveness in solar energy conversion. However, the fabrication of high-quality wide-bandgap perovskite films with a thickness of 1 μm on nano-textured silicon substrates remains a formidable challenge. Herein, we designed an amphoteric coplanar conjugated molecule (ACCM) guided by the principles of density functional theory and Brønsted acid-base chemistry. The inductive effects among the functional groups within the ACCM allow it to exist in various ionic forms. Coupled with its intrinsic π-stacking effect, the ACCM establishes multiple strong interactions with perovskite components, effectively modulating crystallization kinetics and passivating defects. Consequently, both the bulk and interfacial properties of the perovskite films are markedly improved, still maintaining excellent optoelectronic performance even at a thickness of 1 μm. Ultimately, the perovskite/silicon TSCs are developed to achieve exceptional efficiencies of 31.57%, positioning them among the highest levels of TSCs, while also demonstrating outstanding long-term stability under outdoor conditions. This study provides innovative perspectives on the development of organic additives and the optimization of TSCs.