Stabilization of FAPbI 3 with multifunctional alkali-functionalized polymer.

The defects located at the interfaces and grain boundaries (GBs) of perovskite films are detrimental to the photovoltaic performance and stability of perovskite solar cells. Manipulating the perovskite crystallization process and tailoring the interfaces with molecular passivators are mainly effective strategies to mitigate performance loss and instability. Herein we report a new strategy to manipulate the crystallization process of FAPbI 3 -rich perovskite by incorporating a small amount of alkali functionalized polymers into the antisolvent solution. The synergic effects of alkali cations and polyacrylic acid anion effectively passivate the defects on the surface and GBs of perovskite films. As a result, the rubidium (Rb)-functionalized polyacrylic acid significantly improves the power conversion efficiency of FAPbI 3 perovskite solar cells to approaching 25% and reduces the risk of lead ion (Pb 2+ ) leakage via the strong interaction between C = O bond and Pb 2+ . In addition, the unencapsulated device shows enhanced operational stability, retaining 80% of its initial efficiency after 500 h operation at maximum power point under one-sun illumination. This article is protected by copyright. All rights reserved.