Fully Conjugated Biscarboxylate Self‐Assembled Molecule Anchoring Enhances Conductive Oxide for Efficient Textured Perovskite/Silicon Tandem Solar Cells

Abstract The solution‐processible perovskite materials, utilizing the existing silicon infrastructure for perovskite/silicon tandem solar cells (P/S‐TSCs), have attracted significant interest due to their low‐cost and high efficiency. Hole‐selective layers (HSLs) are essential for charge extraction and transport in P/S‐TSCs. However, conventional HSLs often encounter issues such as poor conductivity, energy level mismatch, and incomplete coverage on textured surfaces. In this regard, a novel fully conjugated biscarboxylate‐anchored self‐assembled molecule with limited acidity, 5‐(9H‐dibenzo[a,c]carbazol‐9‐yl)‐isophthalic acid (IPAPhCz), is developed to enhance interaction with the conductive oxide of ITO (Indium tin oxide), which forms a uniform and conformal coverage that significantly improves the crystalline quality of the top perovskite. Additionally, IPAPhCz features a large tilted dipole moment with optimized energy alignment for hole extraction. The resulting 1.68 eV single‐junction PSC achieved a champion power conversion efficiency (PCE) of 22.78%, an increase of ≈10.37% over devices using 4PACz (PCE = 20.64%). Furthermore, textured P/S‐TSCs based on IPAPhCz reached a champion PCE of 31.80% (≈1 cm ² ), reflecting a ≈9.58% enhancement compared to that on 4PACz (PCE = 29.02%). Both devices incorporating IPAPhCz demonstrated improved stability. The findings present a significant methodology for the design of high‐performance HSL materials for textured P/S‐TSCs.