Halide Mixing Inhibits Exciton Transport in Two-dimensional Perovskites Despite Phase Purity.

Michael Seitz,Rafael Delgado-Buscalioni,Daniel A Kurtz,Alvaro J Magdaleno,Mahesh K Gangishetty,Anuraj S Kshirsagar,Nerea Alcázar-Cano,Marc Meléndez,Peyton York,Daniel N Congreve,Ferry Prins

doi:10.1021/acsenergylett.1c02403

Michael Seitz, Rafael Delgado-Buscalioni + Show 9 more

Open Access

https://doi.org/10.1021/acsenergylett.1c02403

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Abstract

Halide mixing is one of the most powerful techniques to tune the optical bandgap of metal-halide perovskites. However, halide mixing has commonly been observed to result in phase segregation, which reduces excited-state transport and limits device performance. While the current emphasis lies on the development of strategies to prevent phase segregation, it remains unclear how halide mixing may affect excited-state transport even if phase purity is maintained. Here, we study exciton transport in phase pure mixed-halide 2D perovskites of (PEA)2Pb(I1–xBrx)4. Using transient photoluminescence microscopy, we show that, despite phase purity, halide mixing inhibits exciton transport. We find a significant reduction even for relatively low alloying concentrations. By performing Brownian dynamics simulations, we are able to reproduce our experimental results and attribute the decrease in diffusivity to the energetically disordered potential landscape that arises due to the intrinsic random distribution of alloying sites.

Highlights

Halide mixing is one of the most powerful techniques to tune the optical bandgap of metal-halide perovskites
Halide mixing can be used in light-emitting devices (LEDs) to fine-tune the color of emission, a strategy that has been successfully employed for both bulk (3D) and layered (2D) perovskites.[17,18]
Phase segregation appears to be absent in 2D perovskites.[12,32−36] This may be attributed to the increased flexibility of the 2D lattice, which is more tolerant to local strain

Summary

Corresponding Author

Michael Seitz − Condensed Matter Physics Center (IFIMAC) and Department of Condensed Matter Physics, Autonomous University of Madrid, 28049 Madrid, Spain; Rowland Institute at Harvard University, Cambridge, Massachusetts 02142, United States; Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States; orcid.org/0000-0002-3515-1648. Magdaleno − Condensed Matter Physics Center (IFIMAC) and Department of Condensed Matter Physics, Autonomous University of Madrid, 28049 Madrid, Spain; orcid.org/0000-0002-9314-7954. Gangishetty − Rowland Institute at Harvard University, Cambridge, Massachusetts 02142, United States; Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States. Rafael Delgado-Buscalioni − Condensed Matter Physics Center (IFIMAC) and Department of Theoretical Condensed Matter Physics, Autonomous University of Madrid, 28049 Madrid, Spain; orcid.org/0000-0001-6637-2091. Congreve − Rowland Institute at Harvard University, Cambridge, Massachusetts 02142, United States; Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States; orcid.org/ 0000-0002-2914-3561.

Author Contributions

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