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Title: Transformation of sintered CsPbBr 3 nanocrystals to cubic CsPbI 3 and gradient CsPbBr xI 3–x through halide exchange

Abstract

All-inorganic cesium lead halide (CsPbX 3, X = Br , I ) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic–inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI 3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI 3 has been developed through a halide exchange reaction using films of sintered CsPbBr 3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reaction times. Thin films (50 nm) showed only a small distribution of CsPbBr xI 3–x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. Furthermore, this ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.

Authors:
 [1];  [1];  [1]
  1. Univ. of Notre Dame, Notre Dame, IN (United States)
Publication Date:
Research Org.:
Univ. of Notre Dame, Notre Dame, IN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1259934
Grant/Contract Number:
FC02-04ER15533
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 138; Journal Issue: 27; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Hoffman, Jacob B., Schleper, A. Lennart, and Kamat, Prashant V.. Transformation of sintered CsPbBr3 nanocrystals to cubic CsPbI3 and gradient CsPbBrxI3–x through halide exchange. United States: N. p., 2016. Web. doi:10.1021/jacs.6b04661.
Hoffman, Jacob B., Schleper, A. Lennart, & Kamat, Prashant V.. Transformation of sintered CsPbBr3 nanocrystals to cubic CsPbI3 and gradient CsPbBrxI3–x through halide exchange. United States. doi:10.1021/jacs.6b04661.
Hoffman, Jacob B., Schleper, A. Lennart, and Kamat, Prashant V.. 2016. "Transformation of sintered CsPbBr3 nanocrystals to cubic CsPbI3 and gradient CsPbBrxI3–x through halide exchange". United States. doi:10.1021/jacs.6b04661.
@article{osti_1259934,
title = {Transformation of sintered CsPbBr3 nanocrystals to cubic CsPbI3 and gradient CsPbBrxI3–x through halide exchange},
author = {Hoffman, Jacob B. and Schleper, A. Lennart and Kamat, Prashant V.},
abstractNote = {All-inorganic cesium lead halide (CsPbX3, X = Br–, I–) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic–inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI3 has been developed through a halide exchange reaction using films of sintered CsPbBr3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reaction times. Thin films (50 nm) showed only a small distribution of CsPbBrxI3–x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. Furthermore, this ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.},
doi = {10.1021/jacs.6b04661},
journal = {Journal of the American Chemical Society},
number = 27,
volume = 138,
place = {United States},
year = 2016,
month = 6
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1021/jacs.6b04661

Citation Metrics:
Cited by: 25works
Citation information provided by
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  • All-inorganic cesium lead halide (CsPbX 3, X = Br , I ) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic–inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI 3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI 3 has been developed through a halide exchange reaction using films of sintered CsPbBr 3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reactionmore » times. Thin films (50 nm) showed only a small distribution of CsPbBr xI 3–x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. Furthermore, this ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.« less
  • All inorganic cesium lead bromide (CsPbBr 3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr 3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr 3 devices. Our layer-by-layer methodology, which makes use of CsPbBr 3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally,more » a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr 3 thickness produce champion devices that reach power conversion efficiencies of 5.5% with a V oc value of 1.4 V. Finally, the layered QD deposition demonstrates a controlled perovskite film architecture for developing efficient, high open-circuit photovoltaic devices.« less
  • All inorganic cesium lead bromide (CsPbBr 3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr 3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr 3 devices. Our layer-by-layer methodology, which makes use of CsPbBr 3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally,more » a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr 3 thickness produce champion devices that reach power conversion efficiencies of 5.5% with a V oc value of 1.4 V. Finally, the layered QD deposition demonstrates a controlled perovskite film architecture for developing efficient, high open-circuit photovoltaic devices.« less