Amphipathic Astaxanthin Additive for Low Voltage-loss Perovskite Solar Cells With Enhanced Quasi-Fermi Level Splitting and Solar Hydrogen Production Application

Even though the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is nearly approaching the Schottky-Queisser limit, low open-circuit voltage (V_oc) and severe V_oc loss problems continue to impede the improvement of PCEs. Astaxanthin (ASTA) additive is introduced in the formamidinium lead triiodide (FAPbI₃) perovskite film as an additive, which can facilitate the transportation of charge carriers and interact with Pb²⁺ by its distinctive groupings. Furthermore, the addition of ASTA decreases the defect's active energy, regulates the deep-level defect by filling up the grain boundaries (GBs), and promotes the crystallization of perovskite film. Remarkably, an enhanced quasi-Fermi level splitting (QFLS) of 1.164 eV and a reduced V_oc loss of only 96 mV are realized. The champion PCE of 24.56% is attained by ASTA-modified PSCs on the basis of 22.75% PCE. Moreover, the PSCs that underwent ASTA modification demonstrate improved operational stability, ensuring consistent output in real-world scenarios. Furthermore, PSCs with an active area of 1 cm² are used for water electrolysis to produce hydrogen and exhibit a PCE of 22.41%. This work offers an environmentally benign solution to address the inherent issues of FAPbI₃ PSCs and lays the groundwork for the development of a prospective solar hydrogen production application.