Multifunctional sulfonium-based treatment for perovskite solar cells with less than 1% efficiency loss over 4,500-h operational stability tests

Abstract

Stabilizing grain boundaries and surfaces of the perovskite layer 45 is critical to extend 46 device durability. Here we introduced an unexplored sulfonium-based molecule to post-treat 47 formamidinium lead iodide perovskite films, which shows outstanding stability upon light soaking 48 and remarkably remains in black-phase after 2 years ageing under ambient condition without 49 encapsulation. The DMPESI-treated PSCs deliver a breakthrough record in operational stability of 50 highly-efficient PSCs with less than 1% performance loss after more than 4500 h at maximum 51 power point tracking, yielding a theoretical T80 of over 9 years under continuous 1-sun 52 illumination. They also present less than 5% PCE drops under various ageing conditions (including 53 thermal cycling and damp heat test).