Low-field onset of Wannier-Stark localization in a polycrystalline hybrid organic inorganic perovskite

Berghoff et al. discover that polycrystalline MAPbI(3) undergoes transient Wannier Stark localization at moderate field strengths, exhibiting substantial optical modulation with a fast response time. Since the polycrystallinity does not hinder the switching behaviour, this low-cost material is promising for light modulation and photonic applications. Methylammonium lead iodide perovskite (MAPbI(3)) is renowned for an impressive power conversion efficiency rise and cost-effective fabrication for photovoltaics. In this work, we demonstrate that polycrystalline MAPbI(3)s undergo drastic changes in optical properties at moderate field strengths with an ultrafast response time, via transient Wannier Stark localization. The distinct band structure of this material - the large lattice periodicity, the narrow electronic energy bandwidths, and the coincidence of these two along the same high-symmetry direction - enables relatively weak fields to bring this material into the Wannier Stark regime. Its polycrystalline nature is not detrimental to the optical switching performance of the material, since the least dispersive direction of the band structure dominates the contribution to the optical response, which favors low-cost fabrication. Together with the outstanding photophysical properties of MAPbI(3), this finding highlights the great potential of this material in ultrafast light modulation and novel photonic applications.

Automated summary

Berghoff et al. found that polycrystalline MAPbI(3) exhibits significant optical modulation and fast response time under moderate field strengths due to transient Wannier Stark localization. Despite its polycrystallinity, this low-cost material shows promise for light modulation and photonic applications.