Dual-interface modification of perovskite solar cells with lithium acetate and hydroxyl functionalized alkynyl derivative

Simultaneous regulation of film morphology and defects at the interface is essential to achieving stable and efficient perovskite solar cells (PSCs). In this study, we synthesized a novel alkynyl passivator DOTB, featured acetylenic π-systems that can engage in π-electron coordination with undercoordinated Pb 2 + and hydroxyl groups that can provide hydrogen bonding with I - anions, thereby modifying perovskite/hole transport layer (HTL) interface. Additionally, we integrated lithium acetate (LiAc) into the electron transport layer (ETL)/perovskite interface. Here LiAc simultaneously functions as a crystallization modulator and defect passivator through Li⁺ diffusion and acetate-mediated interaction. This dual-interface modification strategy accomplishes simultaneous bulk phase passivation and dual interfacial passivation in PSCs. It reduces defect density , enhances crystallization, enhances carrier transport, and reduces non-radiative recombination. As a result, the dual-interface modified PSCs achieve a maximum PCE of 25.48 %. Moreover, the unencapsulated devices demonstrate notably improved stability, preserving above 90 % of their initial performance under ambient air conditions for 1200 hours, and exceeding 80 % following 1000-hours thermal stability assessment conducted at 85 ℃. A dual-interface modification strategy is used to reduce interface defects, improve crystallization, and facilitate carrier transport in perovskite solar cells (PSCs). The synergistic effect of the inorganic salt Lithium Acetate (LiAc) at the electron transport layer (ETL)/perovskite interface and the hydroxyl functionalized alkynyl derivative DOTB at perovskite/ hole transport layer (HTL) interfaces offer a high efficiency of 25.48 % with enhanced long-term stability. • A dual-interface modification strategy is adopted in perovskite solar cells. • Reducing excess PbI 2 by hydroxyl functionalized alkynyl derivative. • LiAc acts as a crystal growth regulator and defect passivator. • Diffused Li + improves the electrical performance and carrier transport. • Achieved 25.48 % power conversion efficiency and excellent operational stability.