Unraveling the Broadband Emission in Mixed Tin-Lead Layered Perovskites

Hong Hua Fang*, Eelco K. Tekelenburg, Haibo Xue, Simon Kahmann, Lijun Chen, Sampson Adjokatse, Geert Brocks, Shuxia Tao, Maria Antonietta Loi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Low-dimensional halide perovskites with broad emission are a hot topic for their promising application as white light sources. However, the physical origin of this broadband emission in the sub-bandgap region is still controversial. This work investigates the broad Stokes-shifted emission bands in mixed lead-tin 2D perovskite films prepared by mixing precursor solutions of phenethylammonium lead iodide (PEA2PbI4, PEA = phenethylammonium) and phenethylammonium tin iodide (PEA2SnI4). The bandgap can be tuned by the lead-tin ratio, whereas the photoluminescence is broad and significantly Stokes-shifted and appears to be fairly insensitive to the relative amount of Pb and Sn. It is experimentally observed that these low-dimensional systems show substantially less bandgap bowing than their 3D counterpart. Theoretically, this can be attributed to the smaller spin–orbit coupling effect on the 2D perovskites compared to that of 3D ones. The time-resolved photoluminescence shows an ultrafast decay in the high-energy range of the spectra that coincides with the emission range of PEA2SnI4, while the broadband emission decay is slower, up to the microsecond range. Sub-gap photoexcitation experiments exclude exciton self-trapping as the origin of the broadband emission, pointing to defects as the origin of the broadband emission in 2D Sn/Pb perovskite alloys.

Original languageEnglish
Article number2202038
JournalAdvanced Optical Materials
Publication statusE-pub ahead of print/First online - 8 Dec 2022


  • bandgap bowing
  • defects
  • mixed lead-tin perovskite
  • Ruddlesden–Popper perovskites
  • 2023 OA procedure


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