Vapor-phase ligand mediates intermediate phase stabilization and crystallization control for efficient perovskite solar cells

Abstract

Perovskite solar cells have emerged as a transformative thin-film photovoltaic technology, in which the crystallization properties of the perovskite film critically influence device performance. However, the complex solvent-involved intermediate phase and uncontrollable premature phase transformation in the perovskite precursor film can dislocate the crystallization process, leading to inhomogeneities and defect-rich domains. Here, we present a vapor-phase ligand-assisted strategy employing 4-methoxybenzylamine to preposition a one-dimensional perovskitoid framework on lead iodide, which thermodynamically stabilizes the intermediate phase of perovskite precursor film at room temperature and inhibits the subsequent heterogeneous crystallization of the perovskite film. The manipulation of that crystallization kinetics minimizes imperfections, optimizes uniformity, resulting in high crystalline quality of perovskite film and effective carrier transport in the corresponding assembled device. Therefore, the optimized solar cell delivers the champion power conversion efficiency reaching 25.47%, accompanied by negligible hysteresis and exceptional operational stability. This study establishes a room temperature stabilization strategy for metastable intermediates, which provides distinct mechanistic insights into crystallization thermodynamics of perovskites.