Rational Electrostatic Iodine Regulation for Photothermally Stable Perovskite Solar Cells

Perovskite solar cells (PSCs), as a promising photovoltaic technology, have achieved remarkable progress in efficiency. However, perovskite with soft-lattice nature inherently suffers from severe iodine losses under photothermal operation, leading to the irreversible degradation in their photovoltaic performance, thereby remaining a great challenge to achieving durable PSCs. Here, electrostatic iodine regulation is reported by rational design on amine cations for photothermally stable PSCs. Theoretical simulations uncover that more alkyl chains binding on the nitrogen atom can not only strengthen the electrostatic interaction between amine cation and triiodine anions (I₃⁻), and the quaternary amine cation can also inhibit the amine cation from deprotonation, yielding much more effective iodine confinement than widely-used van der Waals interactions. After incorporating tetrabutylammonium iodide (TBAI), substantial enhancements on photothermal tolerances are detected on perovskite films with effectively suppressed iodine losses and metal electrode erosions. Additionally, TBAI also promotes the crystallization and passivate defect, resulting in reduced undesirable recombination within perovskite. Consequently, the targeted PSCs realize a champion efficiency of 26.23%. Moreover, the device features superior operational stability and maintains 92.5% of initial efficiency after 1000 h maximum power point (MPP) tracking at 85 °C.