Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites

Advantages of adding just enough alkalis For organic-inorganic hybrid solar cells, addition of cesium or rubidium cations can improve power conversion efficiency. Correa-Baena et al. used nanoscale x-ray fluorescence imaging to show that the addition of metal cations at low concentrations homogenized the distribution of bromide and iodide anions and also increased charge-carrier lifetimes. However, at high concentrations, aggregation and cluster formation led to increased charge recombination. Science , this issue p. 627