Coordination‐Directed Interfacial Assembly for Organic and Perovskite Solar Cells

Supramolecular assembly exhibited by small molecule materials at interfaces holds a pivotal significance in manipulating the charge transport dynamics and light field characteristics within photovoltaic cells. However, the limited understanding and precise control of this assembly behavior pose challenges to the rational design and application of such materials. Here, two pyrazine‐based nitrogen‐rich conjugated molecules is designed. EPCN exhibits a controlled and balanced assembly process due to its more even distribution of intermolecular interactions from its chemical structure, unlike PCN. Accordingly, an extra coordination force is introduced to regulate the irregular assembly of PCN, obtaining uniform hemispherical nanodots with appropriate dimensions. The incorporation of PCN&Zr boosts charge transport and leverages an efficient light scattering effect, achieving a 19.1% efficiency in organic solar cells. Moreover, the coordination assembly feature endows PCN with the functions of defect passivation and Fermi level alignment, yielding efficiencies of 25.4% in 1.55 eV perovskite solar cells, respectively. Leveraging these findings, the optimal 4‐T perovskite‐organic tandem device yields a champion efficiency of 25.43%. This work demonstrates the precise interfacial assembly control via structure tailoring and metal coordination, providing valuable insights into the material design and application of assembly interface materials in both organic and perovskite photovoltaics.