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Cation-Dependent Hot Carrier Cooling in Halide Perovskite Nanocrystals

Chen, Junsheng LU ; Messing, Maria E. LU ; Zheng, Kaibo LU and Pullerits, Tonu LU (2019) In Journal of the American Chemical Society 141(8). p.3532-3540
Abstract


Lead halide perovskites (LHPs) nanocrystals (NCs), owing to their outstanding photophysical properties, have recently emerged as a promising material not only for solar cells but also for lighting and display applications. The photophysical properties of these materials can be further improved by chemical engineering such as cation exchange. Hot carrier (HC) cooling, as one of the key photophysical processes in LHPs, can strongly influence performance of LHPs NCs based devices. Here, we study HC relaxation dynamics in LHP NCs with cesium (Cs), methylammonium (MA, CH
3
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Lead halide perovskites (LHPs) nanocrystals (NCs), owing to their outstanding photophysical properties, have recently emerged as a promising material not only for solar cells but also for lighting and display applications. The photophysical properties of these materials can be further improved by chemical engineering such as cation exchange. Hot carrier (HC) cooling, as one of the key photophysical processes in LHPs, can strongly influence performance of LHPs NCs based devices. Here, we study HC relaxation dynamics in LHP NCs with cesium (Cs), methylammonium (MA, CH
3
NH
3

+
), and formamidinium (FA, CH(NH
2
)
2

+
) cations by using femtosecond transient absorption spectroscopy. The LHP NCs show excitation intensity and excitation energy-dependent HC cooling. We investigate the details of HC cooling in CsPbBr
3
, MAPbBr
3
, and FAPbBr
3
at three different excitation energies with low excitation intensity. It takes longer time for the HCs at high energy to relax (cool) to the band edge, compared to the HCs generated by low excitation energy. At the same excitation energy (350 nm, 3.54 eV), all the three LHP NCs show fast HC relaxation (<0.4 ps) with the cooling time and rate in the following order: CsPbBr
3
(0.39 ps, 2.9 meV/fs) > MAPbBr
3
(0.27 ps, 4.6 meV/fs) > FAPbBr
3
(0.21 ps, 5.8 meV/fs). The cation dependence can be explained by stronger interaction between the organic cations with the Pb-Br frameworks compared to the Cs. The revealed cation-dependent HC relaxation process is important for providing cation engineering strategies for developing high performance LHP devices.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of the American Chemical Society
volume
141
issue
8
pages
3532 - 3540
publisher
The American Chemical Society
external identifiers
  • scopus:85061922466
ISSN
0002-7863
DOI
10.1021/jacs.8b11867
language
English
LU publication?
yes
id
d47954bb-785f-43a5-83c6-6e374b3905ec
date added to LUP
2019-03-04 10:03:28
date last changed
2019-03-27 04:39:44
@article{d47954bb-785f-43a5-83c6-6e374b3905ec,
  abstract     = {<p><br>
                                                         Lead halide perovskites (LHPs) nanocrystals (NCs), owing to their outstanding photophysical properties, have recently emerged as a promising material not only for solar cells but also for lighting and display applications. The photophysical properties of these materials can be further improved by chemical engineering such as cation exchange. Hot carrier (HC) cooling, as one of the key photophysical processes in LHPs, can strongly influence performance of LHPs NCs based devices. Here, we study HC relaxation dynamics in LHP NCs with cesium (Cs), methylammonium (MA, CH                             <br>
                            <sub>3</sub><br>
                                                         NH                             <br>
                            <sub>3</sub><br>
                                                         <br>
                            <sup>+</sup><br>
                                                         ), and formamidinium (FA, CH(NH                             <br>
                            <sub>2</sub><br>
                                                         )                             <br>
                            <sub>2</sub><br>
                                                         <br>
                            <sup>+</sup><br>
                                                         ) cations by using femtosecond transient absorption spectroscopy. The LHP NCs show excitation intensity and excitation energy-dependent HC cooling. We investigate the details of HC cooling in CsPbBr                             <br>
                            <sub>3</sub><br>
                                                         , MAPbBr                             <br>
                            <sub>3</sub><br>
                                                         , and FAPbBr                             <br>
                            <sub>3</sub><br>
                                                          at three different excitation energies with low excitation intensity. It takes longer time for the HCs at high energy to relax (cool) to the band edge, compared to the HCs generated by low excitation energy. At the same excitation energy (350 nm, 3.54 eV), all the three LHP NCs show fast HC relaxation (&lt;0.4 ps) with the cooling time and rate in the following order: CsPbBr                             <br>
                            <sub>3</sub><br>
                                                          (0.39 ps, 2.9 meV/fs) &gt; MAPbBr                             <br>
                            <sub>3</sub><br>
                                                          (0.27 ps, 4.6 meV/fs) &gt; FAPbBr                             <br>
                            <sub>3</sub><br>
                                                          (0.21 ps, 5.8 meV/fs). The cation dependence can be explained by stronger interaction between the organic cations with the Pb-Br frameworks compared to the Cs. The revealed cation-dependent HC relaxation process is important for providing cation engineering strategies for developing high performance LHP devices.                         <br>
                        </p>},
  author       = {Chen, Junsheng and Messing, Maria E. and Zheng, Kaibo and Pullerits, Tonu},
  issn         = {0002-7863},
  language     = {eng},
  number       = {8},
  pages        = {3532--3540},
  publisher    = {The American Chemical Society},
  series       = {Journal of the American Chemical Society},
  title        = {Cation-Dependent Hot Carrier Cooling in Halide Perovskite Nanocrystals},
  url          = {http://dx.doi.org/10.1021/jacs.8b11867},
  volume       = {141},
  year         = {2019},
}