Abstract
Metal halide perovskites are promising solar energy materials, but their mechanism of action remains poorly understood. It has been conjectured that energetically stabilized states such as those corresponding to polarons, quasiparticles in which the carriers are dressed with phonons, are responsible for their remarkable photophysical properties. Yet, no direct evidence of polarons or other low-energy states have been reported despite extensive efforts. Such states should manifest as below bandgap features in transient absorption and photoluminescence measurements. Here, we use single-particle transient absorption microscopy on MAPbI3 (MA = methylammonium) to unambiguously identify spectrally narrow sub-bandgap states directly; we demonstrate that such signals are completely averaged away in ensemble measurements. Carrier temperature-dependent studies suggest that hot carriers are directed toward transient low-energy states which are immune from permanent defects and traps, thereby giving rise to low carrier recombination rates and ultimately high power conversion efficiency in devices. The utilization of short-lived sub-bandgap states may be a key design principle that propels widespread use of highly heterogeneous materials in optoelectronic applications.
| Original language | English |
|---|---|
| Pages (from-to) | 827-831 |
| Number of pages | 5 |
| Journal | Nano Letters |
| Volume | 18 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Feb 14 2018 |
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Keywords
- Metal halide perovskite
- polaron states
- spatially resolved measurements
- transient absorption microscopy
- ultrafast spectroscopy
ASJC Scopus subject areas
- Bioengineering
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering
Cite this
Transient Sub-bandgap States in Halide Perovskite Thin Films. / Nah, S.; Spokoyny, B.; Jiang, X.; Stoumpos, C.; Soe, C. M.M.; Kanatzidis, Mercouri G; Harel, E.
In: Nano Letters, Vol. 18, No. 2, 14.02.2018, p. 827-831.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Transient Sub-bandgap States in Halide Perovskite Thin Films
AU - Nah, S.
AU - Spokoyny, B.
AU - Jiang, X.
AU - Stoumpos, C.
AU - Soe, C. M.M.
AU - Kanatzidis, Mercouri G
AU - Harel, E.
PY - 2018/2/14
Y1 - 2018/2/14
N2 - Metal halide perovskites are promising solar energy materials, but their mechanism of action remains poorly understood. It has been conjectured that energetically stabilized states such as those corresponding to polarons, quasiparticles in which the carriers are dressed with phonons, are responsible for their remarkable photophysical properties. Yet, no direct evidence of polarons or other low-energy states have been reported despite extensive efforts. Such states should manifest as below bandgap features in transient absorption and photoluminescence measurements. Here, we use single-particle transient absorption microscopy on MAPbI3 (MA = methylammonium) to unambiguously identify spectrally narrow sub-bandgap states directly; we demonstrate that such signals are completely averaged away in ensemble measurements. Carrier temperature-dependent studies suggest that hot carriers are directed toward transient low-energy states which are immune from permanent defects and traps, thereby giving rise to low carrier recombination rates and ultimately high power conversion efficiency in devices. The utilization of short-lived sub-bandgap states may be a key design principle that propels widespread use of highly heterogeneous materials in optoelectronic applications.
AB - Metal halide perovskites are promising solar energy materials, but their mechanism of action remains poorly understood. It has been conjectured that energetically stabilized states such as those corresponding to polarons, quasiparticles in which the carriers are dressed with phonons, are responsible for their remarkable photophysical properties. Yet, no direct evidence of polarons or other low-energy states have been reported despite extensive efforts. Such states should manifest as below bandgap features in transient absorption and photoluminescence measurements. Here, we use single-particle transient absorption microscopy on MAPbI3 (MA = methylammonium) to unambiguously identify spectrally narrow sub-bandgap states directly; we demonstrate that such signals are completely averaged away in ensemble measurements. Carrier temperature-dependent studies suggest that hot carriers are directed toward transient low-energy states which are immune from permanent defects and traps, thereby giving rise to low carrier recombination rates and ultimately high power conversion efficiency in devices. The utilization of short-lived sub-bandgap states may be a key design principle that propels widespread use of highly heterogeneous materials in optoelectronic applications.
KW - Metal halide perovskite
KW - polaron states
KW - spatially resolved measurements
KW - transient absorption microscopy
KW - ultrafast spectroscopy
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U2 - 10.1021/acs.nanolett.7b04078
DO - 10.1021/acs.nanolett.7b04078
M3 - Article
VL - 18
SP - 827
EP - 831
JO - Nano Letters
JF - Nano Letters
SN - 1530-6984
IS - 2
ER -