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Title: Ultrafast Imaging of Carrier Transport across Grain Boundaries in Hybrid Perovskite Thin Films

Abstract

For optoelectronic devices based on polycrystalline semiconducting thin films, carrier transport across grain boundaries is an important process in defining efficiency. Here we employ transient absorption microscopy (TAM) to directly measure carrier transport within and across the boundaries in hybrid organic-inorganic perovskite thin films for solar cell applications with 50 nm spatial precision and 300 fs temporal resolution. By selectively imaging sub-bandgap states, our results show that lateral carrier transport is slowed down by these states at the grain boundaries. However, the long carrier lifetimes allow for efficient transport across the grain boundaries. The carrier diffusion constant is reduced by about a factor of 2 for micron-sized grain samples by the grain boundaries. For grain sizes on the order of ~200 nm, carrier transport over multiple grains has been observed within a time window of 5 ns. These observations explain both the shortened photoluminescence lifetimes at the boundaries as well as the seemingly benign nature of the grain boundaries in carrier generation.

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Purdue Univ., West Lafayette, IN (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1468735
Report Number(s):
[NREL/JA-5900-71299]
[Journal ID: ISSN 2380-8195]
Grant/Contract Number:  
[AC36-08GO28308]
Resource Type:
Accepted Manuscript
Journal Name:
ACS Energy Letters
Additional Journal Information:
[ Journal Volume: 3; Journal Issue: 6]; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; optoelectronic devices; semiconducting thin films; polycrystalline; carrier transport

Citation Formats

Snaider, Jordan M., Guo, Zhi, Wang, Ti, Yang, Mengjin, Yuan, Long, Zhu, Kai, and Huang, Libai. Ultrafast Imaging of Carrier Transport across Grain Boundaries in Hybrid Perovskite Thin Films. United States: N. p., 2018. Web. doi:10.1021/acsenergylett.8b00560.
Snaider, Jordan M., Guo, Zhi, Wang, Ti, Yang, Mengjin, Yuan, Long, Zhu, Kai, & Huang, Libai. Ultrafast Imaging of Carrier Transport across Grain Boundaries in Hybrid Perovskite Thin Films. United States. doi:10.1021/acsenergylett.8b00560.
Snaider, Jordan M., Guo, Zhi, Wang, Ti, Yang, Mengjin, Yuan, Long, Zhu, Kai, and Huang, Libai. Mon . "Ultrafast Imaging of Carrier Transport across Grain Boundaries in Hybrid Perovskite Thin Films". United States. doi:10.1021/acsenergylett.8b00560. https://www.osti.gov/servlets/purl/1468735.
@article{osti_1468735,
title = {Ultrafast Imaging of Carrier Transport across Grain Boundaries in Hybrid Perovskite Thin Films},
author = {Snaider, Jordan M. and Guo, Zhi and Wang, Ti and Yang, Mengjin and Yuan, Long and Zhu, Kai and Huang, Libai},
abstractNote = {For optoelectronic devices based on polycrystalline semiconducting thin films, carrier transport across grain boundaries is an important process in defining efficiency. Here we employ transient absorption microscopy (TAM) to directly measure carrier transport within and across the boundaries in hybrid organic-inorganic perovskite thin films for solar cell applications with 50 nm spatial precision and 300 fs temporal resolution. By selectively imaging sub-bandgap states, our results show that lateral carrier transport is slowed down by these states at the grain boundaries. However, the long carrier lifetimes allow for efficient transport across the grain boundaries. The carrier diffusion constant is reduced by about a factor of 2 for micron-sized grain samples by the grain boundaries. For grain sizes on the order of ~200 nm, carrier transport over multiple grains has been observed within a time window of 5 ns. These observations explain both the shortened photoluminescence lifetimes at the boundaries as well as the seemingly benign nature of the grain boundaries in carrier generation.},
doi = {10.1021/acsenergylett.8b00560},
journal = {ACS Energy Letters},
number = [6],
volume = [3],
place = {United States},
year = {2018},
month = {5}
}

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Figures / Tables:

Figure 1 Figure 1: (a) Top panel: absorption spectra for perovskite thin films with grain sizes >1 µm (film 1) and < 500 nm (film 2). Lower panel: ensemble transient absorption spectra at 10 ps time delays (630 nm pump) for film 1. (b) Carrier dynamics pumped at 630 nm, probed atmore » 755 nm and probed at 785 nm. c) and d) Morphological TAM images of perovskite thin film taken at 10 ps time delay between pump (630 nm) and probe (755 nm for c and 785 nm for d). Scale bars are 1 µm.« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.