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Title: Design Principles for Trap-Free CsPbX 3 Nanocrystals: Enumerating and Eliminating Surface Halide Vacancies with Softer Lewis Bases

Abstract

We introduce a general surface passivation mechanism for cesium lead halide perovskite materials (CsPbX 3, X = Cl, Br, I) that is supported by a combined experimental and theoretical study of the nanocrystal surface chemistry. A variety of spectroscopic methods are employed together with ab initio calculations to identify surface halide vacancies as the predominant source of charge trapping. The number of surface traps per nanocrystal is quantified by 1H NMR spectroscopy, and that number is consistent with a simple trapping model in which surface halide vacancies create deleterious under-coordinated lead atoms. These halide vacancies exhibit trapping behavior that differs among CsPbCl 3, CsPbBr 3, and CsPbI 3. Ab initio calculations suggest that introduction of anionic X-type ligands can produce trap-free band gaps by altering the energetics of lead-based defect levels. General rules for selecting effective passivating ligand pairs are introduced by considering established principles of coordination chemistry. Introducing softer, anionic, X-type Lewis bases that target under-coordinated lead atoms results in absolute quantum yields approaching unity and monoexponential luminescence decay kinetics, thereby indicating full trap passivation. This work provides a systematic framework for preparing highly luminescent CsPbX 3 nanocrystals with variable compositions and dimensionalities, thereby improving the fundamental understanding ofmore » these materials and informing future synthetic and post-synthetic efforts toward trap-free CsPbX 3 nanocrystals.« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [3]; ORCiD logo [4]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Univ. of California, Berkeley, CA (United States). Kavli Energy NanoScience Inst.; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1542345
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 140; Journal Issue: 50; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Nenon, David P., Pressler, Kimo, Kang, Jun, Koscher, Brent A., Olshansky, Jacob H., Osowiecki, Wojciech T., Koc, Matthew A., Wang, Lin-Wang, and Alivisatos, A. Paul. Design Principles for Trap-Free CsPbX3 Nanocrystals: Enumerating and Eliminating Surface Halide Vacancies with Softer Lewis Bases. United States: N. p., 2018. Web. doi:10.1021/jacs.8b11035.
Nenon, David P., Pressler, Kimo, Kang, Jun, Koscher, Brent A., Olshansky, Jacob H., Osowiecki, Wojciech T., Koc, Matthew A., Wang, Lin-Wang, & Alivisatos, A. Paul. Design Principles for Trap-Free CsPbX3 Nanocrystals: Enumerating and Eliminating Surface Halide Vacancies with Softer Lewis Bases. United States. doi:10.1021/jacs.8b11035.
Nenon, David P., Pressler, Kimo, Kang, Jun, Koscher, Brent A., Olshansky, Jacob H., Osowiecki, Wojciech T., Koc, Matthew A., Wang, Lin-Wang, and Alivisatos, A. Paul. Sun . "Design Principles for Trap-Free CsPbX3 Nanocrystals: Enumerating and Eliminating Surface Halide Vacancies with Softer Lewis Bases". United States. doi:10.1021/jacs.8b11035. https://www.osti.gov/servlets/purl/1542345.
@article{osti_1542345,
title = {Design Principles for Trap-Free CsPbX3 Nanocrystals: Enumerating and Eliminating Surface Halide Vacancies with Softer Lewis Bases},
author = {Nenon, David P. and Pressler, Kimo and Kang, Jun and Koscher, Brent A. and Olshansky, Jacob H. and Osowiecki, Wojciech T. and Koc, Matthew A. and Wang, Lin-Wang and Alivisatos, A. Paul},
abstractNote = {We introduce a general surface passivation mechanism for cesium lead halide perovskite materials (CsPbX3, X = Cl, Br, I) that is supported by a combined experimental and theoretical study of the nanocrystal surface chemistry. A variety of spectroscopic methods are employed together with ab initio calculations to identify surface halide vacancies as the predominant source of charge trapping. The number of surface traps per nanocrystal is quantified by 1H NMR spectroscopy, and that number is consistent with a simple trapping model in which surface halide vacancies create deleterious under-coordinated lead atoms. These halide vacancies exhibit trapping behavior that differs among CsPbCl3, CsPbBr3, and CsPbI3. Ab initio calculations suggest that introduction of anionic X-type ligands can produce trap-free band gaps by altering the energetics of lead-based defect levels. General rules for selecting effective passivating ligand pairs are introduced by considering established principles of coordination chemistry. Introducing softer, anionic, X-type Lewis bases that target under-coordinated lead atoms results in absolute quantum yields approaching unity and monoexponential luminescence decay kinetics, thereby indicating full trap passivation. This work provides a systematic framework for preparing highly luminescent CsPbX3 nanocrystals with variable compositions and dimensionalities, thereby improving the fundamental understanding of these materials and informing future synthetic and post-synthetic efforts toward trap-free CsPbX3 nanocrystals.},
doi = {10.1021/jacs.8b11035},
journal = {Journal of the American Chemical Society},
number = 50,
volume = 140,
place = {United States},
year = {2018},
month = {12}
}

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