Ultra-uniform perovskite film with minimized interconnection energy loss for efficient perovskite/TOPCon tandem solar cells

Perovskite/silicon tandem solar cells (TSCs) are advancing swiftly, with tunnel oxide passivated contact (TOPCon) silicon-based cells gaining prominence owing to their cost-effectiveness and market presence. However, perovskite/TOPCon silicon TSCs currently lag behind their heterojunction (HJT) silicon-based counterparts, due to challenges in depositing uniform films on micro-rough textured substrates. In this work, we introduce a novel interconnection layer (ICL) with an asymmetric molecule, (4-(3-methyl-9H-carbazol-9-yl)butyl)phosphonic acid (3-Me-4PACz). The substantial dipole moment of the molecule effectively reduces the interfacial energy offset, significantly increasing the open-circuit voltage ( V _OC ) of 1.68-eV perovskite subcells over 1.30 V. Furthermore, this tailored ICL exhibits markedly improved wettability, homogeneity, and surface adhesion, successfully eliminating “wet patches.” Consequently, the resulting 1-cm² perovskite/TOPCon silicon TSCs achieved a record certificated power conversion efficiency (PCE) of 32.32% (in-house measurement of 33.12%), alongside an unprecedented V _OC of 2.023 V (certified at 2.015 V), demonstrating a broadly applicable strategy for advancing industrially viable tandem photovoltaics.