Balanced Coordination Chemistry for Architecture-Universal Perovskite Solar Cells

Abstract

Lewis base additives are a ubiquitous tool for enhancing the performance of solution-processed perovskite solar cells (PSCs). However, their development has largely relied on empirical selection, limiting universal applicability across different device architectures. A fundamental understanding of how coordination chemistry governs crystallization, and thus performance, remains elusive. Here, we demonstrate that superior performance in FAPbI3-based PSCs is dictated by a principle of balanced coordination strength. Through systematic investigation of a representative panel of structurally diverse molecules, we reveal that an intermediate Lewis basicity, striking a balance between excessively strong and weak coordination, establishes a thermodynamically and kinetically favorable pathway that promotes the formation of the α-phase while effectively suppressing defect formation. This “balanced coordination” strategy yields high-quality perovskite films and enables universal high performance across both n-i-p and p-i-n architectures, achieving a power conversion efficiency (PCE) of 26.12% (certified 25.62%) in n-i-p devices and 26.56% in p-i-n devices, along with significantly improved operational stability. This work provides microscopic insight into the coordination chemistry of additive design, offering a rational pathway toward high-performance, stable, and architecture-universal perovskite photovoltaics.