Beyond the Sum of Its Parts: Alkyl‐Chain Engineering Unlocks Dopant‐Free Pyrene‐Based Antenna Molecules for Efficient Perovskite Solar Cells

Abstract

ABSTRACT The pursuit of high‐performance, dopant‐free hole‐transporting materials (HTMs) is central to advancing the efficiency and stability of perovskite solar cells (PSCs). Herein, three pyrene‐based HTMs ( PyTPA‐9C , PyTPA‐10C , and PyTPA‐13C ) were synthesized by covalently linking two pyrene‐triphenylamine precursor units, which display a pronounced antenna effect analogous to the precursor which is quantitatively defined by a positive correlation between the number of TPA antenna moieties and key photophysical parameters (such as molar absorption coefficient and fluorescence quantum yield). Critically, the odd‐even effect of the alkyl spacer plays a significant role in modulating the molecular conformation and electronic structure. Moreover, PyTPA‐10C , featuring an even‐carbon decyl chain as a dopant‐free HTMs in n‐i‐p structured PSCs, achieves a champion power conversion efficiency (PCE) of 25.47%, representing the highest reported values for n‐i‐p PSCs employing dopant‐free, organic small‐molecule HTMs. Comprehensive analysis reveals that PyTPA‐10C enables superior hole extraction/transport, effectively suppresses charge recombination, and passivates interfacial defects. Consequently, unencapsulated devices retain over 90% of their initial PCE after 1000 h under continuous heating and illumination at 65°C and 50%–60% relative humidity. This study not only presents high‐performing materials but also establishes a general molecular design strategy: the integration of an “antenna effect” with precise alkyl‐chain engineering.