Unraveling the Broadband Emission in Mixed Tin-Lead Layered Perovskites

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

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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
Number of pages7
JournalAdvanced Optical Materials
Issue number4
Early online date8 Dec 2022
Publication statusPublished - 17 Feb 2023

Bibliographical note

Funding Information:
Arjen Kamp and Teodor Zaharia are thanked for their technical support. H.‐H.F. acknowledges the financial support of the National Natural Science Foundation of China (Grant No: 62075115). S.K. is grateful for a research fellowship (Grant No: 408012143) awarded by the Deutsche Forschungsgemeinschaft (DFG). E.K.T. acknowledges the financial support of the Zernike Institute of Advanced Materials. This work was financed through the Materials for Sustainability (Mat4Sus) programme (739.017.005) of the Netherlands Organization for Scientific Research (NWO). This work is part of the research program of the Foundation for Fundamental Research on Matter (FOM), which is part of the Netherlands Organization for Scientific Research (NWO). This is a publication of the FOM focus Group “Next Generation Organic Photovoltaics” participating in the Dutch Institute for Fundamental Energy Research (DIFFER).


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


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