Excess PbI₂ Management via Multimode Supramolecular Complex Engineering Enables High‐Performance Perovskite Solar Cells

Abstract

Excess PbI2 in perovskite film is an effective strategy for boosting perovskite solar cells (PSCs) performance. However, the presence of unreacted PbI2 is a critical source of intrinsic instability in perovskite under illumination, due to the photolysis of PbI2 (decomposed into metallic lead and iodine). Herein, this issue is solved by applying ionic liquids (ILs) on PSCs where the ILs can form types of stable supramolecules with residual lead iodide. The formation process and mechanism of the supramolecules are elucidated. The residual PbI2 is also revealed to cause high level lead interstitial defects and induced tensile strain which further deteriorate device performance. The self‐assembled supramolecular complex can passivate the PSCs where significant enhancements are achieved in both power conversion efficiency (PCE, from 21.9% to 23.4%) and device stability (retaining 95% of the initial PCE after 4080 h in ambient dry‐air storage, and 80% after 1400 h continuous light illumination).

Direct In Situ Conversion of Lead Iodide to a Highly Oriented and Crystallized Perovskite Thin Film via Sequential Deposition for 23.48% Efficient and Stable Photovoltaic Devices

“…The carrier lifetime is longer for the control group perovskite film measured from the back side than that of the front side. According to the SEM diagram (Figure g,i and Figure S7) and GIWAXS results (Figure f) of the perovskite, this may be due to the excessive residual PbI 2 on the front-side surface of the control group perovskite (relative to the buried interface), which increases the trap density on the front-side surface. , The great improvement of the PL intensity and carrier lifetime on the back side of the perovskite treated with FAFa compared to the control group proves that the FAFa preplaced at the buried interface specifically inhibits the anion vacancy defects enriched at the buried interface.…”

Role of Ionic Liquids in Perovskite Solar Cells

“…Reproduced with permission. [ 74 ] Copyright 2022, Wiley‐VCH. m) Stability of the control and [BMIM]Br‐treated devices (the statistical data of each condition are collected from five devices).…”

Surface Hydrophobicity Engineering of Pt-Based Noble Metal Aerogels by Ionic Liquids toward Enhanced Electrocatalytic Oxygen Reduction

“…Ionic liquids (ILs) are a class of salt solutions composed by anions and cations, usually with the low melting point, high ionic conductivity, good chemical and thermal stability, and highly adjustable solubility . These unique properties of ILs have attracted great interests and applications in fuel cells, water electrolysis, and so on. − In particular, ILs have been widely employed as surface modifiers of catalysts to regulate the surface properties and performance of electrocatalysts. − For example, Li et al demonstrated the PtFeNi/ionic liquid conjugate system, which greatly enhanced the ORR activity and durability compared to the non-conjugated counterpart . The above inspiring works imply the great potential of ILs as the surface ligands to reveal the regularity between surface properties and electrocatalytic activity.…”