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Reconfiguring the Band-Edge States of Lead-Halide Perovskite Semiconductors

Feb. 25, 2021

We report a π-conjugation-induced extension of electronic states of A-site cations that impacts perovskite frontier orbitals. The π-conjugated pyrene-containing A-site cations electronically contribute to the surface band edges and impact the carrier dynamics with a properly tailored intercalation distance between the inorganic framework. The ethylammonium pyrene increased hole mobilities, improved power conversion efficiencies relative to a reference perovskite, and also improved device stability.

Scientific Achievement

We showed that appropriately functionalized pyrene organic cations contribute to the band-edge states in lead (Pb)-halide perovskite semiconductors and improves surface carrier dynamics.

Significance and Impact

Surfaces and interfaces drive photoconversion and help protect the underlying bulk material. Molecules that can couple electronically to the underlying material provide additional design rules for controlling opto-electronic behavior.

Research Details

  • Three pyrene derivatives with different ammonium anchor groups
  • Photoelectron spectroscopy and theory demonstrate coupling of band-edge states with perovskite states
  • Measured impact on carrier dynamics and solar cells

DOI: 10.1126/science.abd4860

Related People

Kai Zhu
National Renewable Energy Laboratory

Matthew Beard
National Renewable Energy Laboratory

Yanfa Yan
University of Toledo

Charts showing density of state and energy (eV) for PRA, PRMA, and PREA; and a chart showing binding energy for PREA, PRMA, and PRA.

Three A-site pyrene derivatives terminate perovskite films with different length of the anchor ammonium functional group.  Both photoelectron and spectroscopy theory show that different anchoring groups modifies how pyrene moiety couples to the inorganic lattice.