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Title: Interconversion between Free Charges and Bound Excitons in 2D Hybrid Lead Halide Perovskites

Abstract

The optoelectronic properties of hybrid perovskites can be easily tailored by varying their components. Specifically, mixing the common short organic cation (methylammonium (MA)) with a larger one (e.g., butyl ammonium (BA)) results in 2-dimensional perovskites with varying thicknesses of inorganic layers separated by the large organic cation. In both of these applications, a detailed understanding of the dissociation and recombination of electron–hole pairs is of prime importance. Here in this work, we give a clear experimental demonstration of the interconversion between bound excitons and free charges as a function of temperature by combining microwave conductivity techniques with photoluminescence measurements. We demonstrate that the exciton binding energy varies strongly (between 80 and 370 meV) with the thickness of the inorganic layers. Additionally, we show that the mobility of charges increases with the layer thickness, in agreement with calculated effective masses from electronic structure calculations.

Authors:
 [1]; ORCiD logo [1];  [2];  [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Delft Univ. of Technology (Netherlands). Section Optoelectronic Materials, Dept. of Chemical Engineering
  2. Northwestern Univ., Evanston, IL (United States). Argonne-Northwestern Solar Energy Research Center (ANSER), Dept. of Chemistry
Publication Date:
Research Org.:
Northwestern Univ., Evanston, IL (United States). Argonne-Northwestern Solar Energy Research (ANSER)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1413217
Grant/Contract Number:
SC0001059; 712.014.007
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 47; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Gélvez-Rueda, María C., Hutter, Eline M., Cao, Duyen H., Renaud, Nicolas, Stoumpos, Constantinos C., Hupp, Joseph T., Savenije, Tom J., Kanatzidis, Mercouri G., and Grozema, Ferdinand C. Interconversion between Free Charges and Bound Excitons in 2D Hybrid Lead Halide Perovskites. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b10705.
Gélvez-Rueda, María C., Hutter, Eline M., Cao, Duyen H., Renaud, Nicolas, Stoumpos, Constantinos C., Hupp, Joseph T., Savenije, Tom J., Kanatzidis, Mercouri G., & Grozema, Ferdinand C. Interconversion between Free Charges and Bound Excitons in 2D Hybrid Lead Halide Perovskites. United States. doi:10.1021/acs.jpcc.7b10705.
Gélvez-Rueda, María C., Hutter, Eline M., Cao, Duyen H., Renaud, Nicolas, Stoumpos, Constantinos C., Hupp, Joseph T., Savenije, Tom J., Kanatzidis, Mercouri G., and Grozema, Ferdinand C. 2017. "Interconversion between Free Charges and Bound Excitons in 2D Hybrid Lead Halide Perovskites". United States. doi:10.1021/acs.jpcc.7b10705. https://www.osti.gov/servlets/purl/1413217.
@article{osti_1413217,
title = {Interconversion between Free Charges and Bound Excitons in 2D Hybrid Lead Halide Perovskites},
author = {Gélvez-Rueda, María C. and Hutter, Eline M. and Cao, Duyen H. and Renaud, Nicolas and Stoumpos, Constantinos C. and Hupp, Joseph T. and Savenije, Tom J. and Kanatzidis, Mercouri G. and Grozema, Ferdinand C.},
abstractNote = {The optoelectronic properties of hybrid perovskites can be easily tailored by varying their components. Specifically, mixing the common short organic cation (methylammonium (MA)) with a larger one (e.g., butyl ammonium (BA)) results in 2-dimensional perovskites with varying thicknesses of inorganic layers separated by the large organic cation. In both of these applications, a detailed understanding of the dissociation and recombination of electron–hole pairs is of prime importance. Here in this work, we give a clear experimental demonstration of the interconversion between bound excitons and free charges as a function of temperature by combining microwave conductivity techniques with photoluminescence measurements. We demonstrate that the exciton binding energy varies strongly (between 80 and 370 meV) with the thickness of the inorganic layers. Additionally, we show that the mobility of charges increases with the layer thickness, in agreement with calculated effective masses from electronic structure calculations.},
doi = {10.1021/acs.jpcc.7b10705},
journal = {Journal of Physical Chemistry. C},
number = 47,
volume = 121,
place = {United States},
year = 2017,
month =
}

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  • Here, we report the first high-pressure single-crystal structures of hybrid perovskites. The crystalline semiconductors (MA)PbX 3 (MA = CH 3NH 3 +, X = Br or I ) afford us the rare opportunity of understanding how compression modulates their structures and thereby their optoelectronic properties. Using atomic coordinates obtained from high-pressure single-crystal X-ray diffraction we track the perovskites’ precise structural evolution upon compression. These structural changes correlate well with pressure-dependent single-crystal photoluminescence (PL) spectra and high-pressure bandgaps derived from density functional theory. We further observe dramatic piezochromism where the solids become lighter in color and then transition to opaquemore » black with compression. Indeed, electronic conductivity measurements of (MA)PbI 3 obtained within a diamond-anvil cell show that the material’s resistivity decreases by 3 orders of magnitude between 0 and 51 GPa. The activation energy for conduction at 51 GPa is only 13.2(3) meV, suggesting that the perovskite is approaching a metallic state. Furthermore, the pressure response of mixed-halide perovskites shows new luminescent states that emerge at elevated pressures. We recently reported that the perovskites (MA)Pb(Br xI 1–x) 3 (0.2 < x < 1) reversibly form light-induced trap states, which pin their PL to a low energy. This may explain the low voltages obtained from solar cells employing these absorbers. Our high-pressure PL data indicate that compression can mitigate this PL redshift and may afford higher steady-state voltages from these absorbers. These studies show that pressure can significantly alter the transport and thermodynamic properties of these technologically important semiconductors.« less
    Cited by 24
  • Here, we report the first high-pressure single-crystal structures of hybrid perovskites. The crystalline semiconductors (MA)PbX 3 (MA = CH 3NH 3 +, X = Br or I ) afford us the rare opportunity of understanding how compression modulates their structures and thereby their optoelectronic properties. Using atomic coordinates obtained from high-pressure single-crystal X-ray diffraction we track the perovskites’ precise structural evolution upon compression. These structural changes correlate well with pressure-dependent single-crystal photoluminescence (PL) spectra and high-pressure bandgaps derived from density functional theory. We further observe dramatic piezochromism where the solids become lighter in color and then transition to opaquemore » black with compression. Indeed, electronic conductivity measurements of (MA)PbI 3 obtained within a diamond-anvil cell show that the material’s resistivity decreases by 3 orders of magnitude between 0 and 51 GPa. The activation energy for conduction at 51 GPa is only 13.2(3) meV, suggesting that the perovskite is approaching a metallic state. Furthermore, the pressure response of mixed-halide perovskites shows new luminescent states that emerge at elevated pressures. We recently reported that the perovskites (MA)Pb(Br xI 1–x) 3 (0.2 < x < 1) reversibly form light-induced trap states, which pin their PL to a low energy. This may explain the low voltages obtained from solar cells employing these absorbers. Our high-pressure PL data indicate that compression can mitigate this PL redshift and may afford higher steady-state voltages from these absorbers. These studies show that pressure can significantly alter the transport and thermodynamic properties of these technologically important semiconductors.« less
  • Organic-inorganic hybrid halide perovskites are a promising class of materials for photovoltaic application with reported power efficiencies over similar to 22%. However, not much is known about the influence of the organic dipole rotation and phase transitions on charge carrier dynamics. Here, we report substantial changes in mobility and lifetime of charge carriers in CH 3NH 3PbI 3 after the low-temperature tetragonal (beta) to orthorhombic (gamma) phase transition. By using microwave conductivity measurements, we observed that the mobility and lifetime of ionized charge carriers increase as the temperature decreases and a sudden increment is seen after the beta-gamma phase transition.more » For CH 3NH 3PbI 3, the mobility and the half-lifetime increase by a factor of 36 compared with the values before the beta-gamma phase transition. We attribute the considerable change in the dynamics at low temperature to the decrease of the inherent dynamic disorder of the organic cation (CH 3NH 3+) inside the perovskite crystal structure.« less