Synergistic Enhancement of Stability and Performance for Perovskite Solar Cells Using Fluorinated Benzoic Acids as Additives

Abstract

The power conversion efficiency of perovskite solar cells (PSCs) has increased dramatically over the past decade, reaching more than 26%. With such high efficiency, PSCs could become one of the most important commercial alternatives to silicon‐based solar cells in the near future. However, the inconsistency of PSC operation over time is the key issue restricting its commercial application. One of the most common means of improving the overall stability of PSCs is the introduction of additives with specific functional groups to extend their useful life. Here we compare the performance and stability of MAPbI3‐based PSCs with additions of either benzoic acid (0F‐B), fluorinated benzoic acids (4‐fluorobenzoic acid (1F‐B), or 2,3,4,5,6‐pentafluorobenzoic acid (5F‐B)) in the perovskite active layer. These additives, upon interacting with the perovskite precursors, chelate onto lead ions and form hydrogen bond with methyl ammonium ions. These combined interactions result in an increased activation energy for nucleation of perovskite crystals, thereby, increased crystal size, reduced defect formation, improved electronic properties, as well as reduced ion migration. As a result, PSCs added with largest fluorine substitution of 5F‐B achieve the highest efficiency of 20.50% with a narrow PCE distribution compared to that of PSC devices added with 1F‐B (19.25%), 0F‐B (18.80%) and pristine devices (18.53%). Notably, 5F‐B added PSCs retain 80% of their initial PCE after ∽100 days humidity test (at 25 °C and 50 RH%), 30 days thermal stability test (at 85 °C in nitrogen environment), and 12 days light illumination test (continuous simulated solar radiation). Therefore, 5F‐B added PSCs synergistically achieve the highest performance and remain very stable under constant heat, humidity, or light illumination conditions for sustained energy‐harvesting applications in the future.TOC: This study focuses on the impacts of benzoic acid and its fluorinated derivatives functioning as effective passivation additives for methyl ammonium lead iodide (MAPbI3) perovskite solar cells. These additives synergistically passivate the perovskite layer, resulting in improved crystallinity and surface morphology, leading to an increased efficiency. Moreover, this approach enhances the long‐term stability of the architected solar cells, rendering them more suitable for future commercial applications.This article is protected by copyright. All rights reserved.