Snaith group

Abstract:

Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single-junction counterparts. However, overcoming the significant open-circuit voltage deficit present in wide-bandgap perovskite solar cells remains a major hurdle for realizing efficient and stable perovskite tandem cells. Here, a holistic approach to overcoming challenges in 1.8 eV perovskite solar cells is reported by engineering the perovskite crystallization pathway by means of chloride additives. In conjunction with employing a self-assembled monolayer as the hole-transport layer, an open-circuit voltage of 1.25 V and a power conversion efficiency of 17.0% are achieved. The key role of methylammonium chloride addition is elucidated in facilitating the growth of a chloride-rich intermediate phase that directs crystallization of the desired cubic perovskite phase and induces more effective halide homogenization. The as-formed 1.8 eV perovskite demonstrates suppressed halide segregation and improved optoelectronic properties.

Abstract:

Inside Front Cover
In article number 2300095, Hesjedal and co-workers demonstrate that the substitution of Co2+ ions into the halide perovskite imparts magnetic behavior to the material while maintaining photovoltaic performance. We utilize the Co2+ ions (shown as robots) themselves as probes to sense the local electronic environment of lead in the perovskite, thereby opening the substitution gateway for developing novel functional perovskite materials and devices for future technologies.