Graphene-polymer reinforcement of perovskite lattices for durable solar cells.

The lattice deformation and structural evolution of perovskite films in response to electric fields, temperature, and light limit the operational endurance of solar cells. We mechanically reinforced perovskite thin films by integrating a polymer-coupled monolithic single-layer graphene interface that led to a twofold enhancement in modulus and hardness. The synergistic effect of graphene and poly(methyl methacrylate) restricted photoinduced lattice expansion and decreased the deformation ratio from 0.31 to 0.08%, which minimized the structural damage caused by dynamic lattice evolution. Solar cell devices maintained >97% of their initial power conversion efficiency after maximum power point tracking for >3670 hours under full-spectrum air mass 1.5 global (AM 1.5 G) sunlight at 90°C. Editor's summary: Using a polymer to couple single-layer graphene to a perovskite lattice can reduce photoinduced expansion and consequent solar cell damage. Li et al. show that mechanical reinforcement by the interlayer decreased the deformation ratio under operation by a factor of four and also reduced ion migration (see the Perspective by Saliba and Zuo). Solar cell devices with the bilayer structure retained more than 97% of their initial power conversion efficiency of over 25% after maximum power point operation at 90°C for 3670 hours. —Phil Szuromi [ABSTRACT FROM AUTHOR]