Insights into iodoplumbate complex evolution of precursor solutions for perovskite solar cells: from aging to degradation

Abstract

The power conversion efficiency (PCE) of solution-processed perovskite solar cells (PSCs) is significantly influenced by the characteristics of the perovskite precursor solutions. Iodoplumbate complexes such as PbI₂, PbI₃⁻, and PbI₄²⁻ present in perovskite precursor solution in equilibria dictate the quality of perovskite films and the corresponding optoelectrical performance of PSCs. Meanwhile, the solvent and additive molecules compete with I⁻ to coordinate with Pb²⁺ and shift the chemical equilibria based on their coordination capabilities. The proportion and species of iodoplumbate complexes have a time-dependent influence on the subsequent perovskite crystallization and the quality of perovskite films. This review presents the impact of the evolution of the characteristics of a perovskite precursor solution driven by the components of the precursor solution, aging, degradation, and humidity on the physical properties of perovskite films and the photovoltaic performance of PSCs. A brief outlook on further improving the reproducibility window for PSCs fabricated by the solution process is provided based on the current research progress in terms of perovskite precursor evolution in PSCs.