Metallurgy

Materials science

Perovskite (structure)

Silicon

Band gap

Tandem

Nanotechnology

Organic chemistry

Bromine

Composite material

Crystallography

Chemistry

Energy conversion efficiency

Optoelectronics

Science

Engineering perovskites with anions The bandgap of the perovskite top layer in tandem silicon solar cells must be tuned to ∼1.7 electron volts. Usually, the cation composition is varied because the bromine-rich anion compositions with wide bandgaps are structurally unstable. Kim et al. show that by using phenethylammonium as a two-dimensional additive, along with iodine and thiocyanate, bromine-rich perovskite films can be stabilized. A tandem silicon cell delivered &gt;26% certified power conversion efficiency, and a perovskite device maintained 80% of its initial power conversion efficiency of &gt;20% after 1000 hours under illumination. Science , this issue p. 155

Efficient, stable silicon tandem cells enabled by anion-engineered wide-bandgap perovskites