A trifluorothymine interlayer reduces the degradation of perovskite and controls the cracks of hole transport layers

Abstract

The construction of a powerful molecular interlayer is beneficial to the enhancement of both efficiency and stability of perovskite solar cells. We herein disclose that low-cost trifluorothymine with Lewis acid (protons of NH) and base (carbonyl oxygens) sites as well as hydrophobic moiety (trifluoromethyl) can be exploited as a robust molecular passivator for organic–inorganic hybrid lead iodide based perovskites. The lead and iodine promoted self-organization of amphiphilic trifluorothymine molecules can not only remove some electron and hole traps on the surface of perovskite and attenuate interfacial charge recombination, but also markedly reduce the thermal decomposition of hybrid perovskites and control the cracks of organic hole transport layers. Perovskite solar cells with a trifluorothymine interlayer maintain about 90% of initial efficiency after 1000 h aging at 85 °C. We demonstrate that the judicious combination of a potent trifluorothymine interlayer with a high glass transition temperature organic hole transport layer, a triple-cation lead iodide based perovskite, and an oxide electron transport layer is a practical strategy for the fabrication of efficient and durable perovskite solar cells.