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Charge Carrier Diffusion Dynamics in Multisized Quaternary Alkylammonium-Capped CsPbBr3 Perovskite Nanocrystal Solids
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SYSNO ASEP 0555266 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Charge Carrier Diffusion Dynamics in Multisized Quaternary Alkylammonium-Capped CsPbBr3 Perovskite Nanocrystal Solids Author(s) Alvarez, S. (DK)
Lin, W. (SE)
Abdellah, M. (SE)
Meng, J. (DK)
Žídek, Karel (UFP-V) ORCID
Pullerits, T. (SE)
Zheng, K. (SE)Number of authors 7 Source Title ACS Applied Materials and Interfaces. - : American Chemical Society - ISSN 1944-8244
Roč. 13, č. 37 (2021), s. 44742-44750Number of pages 9 s. Language eng - English Country US - United States Keywords light-emitting-diodes ; metal-halide perovskites ; quantum dots ; energy-transfer ; lengths ; mobilities ; efficiency ; trihalide ; films ; ultrafast spectroscopy ; diffusion lengths ; CsPbBr3 ; ddab ; quantum dot photovoltaics ; carrier transport ; charge transfer Subject RIV JP - Industrial Processing OECD category Materials engineering R&D Projects EF16_026/0008390 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Method of publishing Open access Institutional support UFP-V - RVO:61389021 UT WOS 000700877100087 DOI 10.1021/acsami.1c11676 Annotation CsPbBr3 quantum dots (QDs) are promising candidates for optoelectronic devices. The substitution of oleic acid ( OA) and oleylamine ( OLA) capping agents with a quaternary alkylammonium such as di-dodecyl dimethyl ammonium bromide (DDAB) has shown an increase in external quantum efficiency (EQE) from 0.19% (OA/OLA) to 13.4% (DDAB) in LED devices. The device performance significantly depends on both the diffusion length and the mobility of photoexcited charge carriers in QD solids. Therefore, we investigated the charge carrier transport dynamics in DDAB-capped CsPbBr3 QD solids by constructing a bi-sized QD mixture film. Charge carrier diffusion can be monitored by quantitatively varying the ratio between two sizes of QDs, which varies the mean free path of the carriers in each QD cluster. Excited-state dynamics of the QD solids obtained from ultrafast transient absorption spectroscopy reveals that the photogenerated electrons and holes are difficult to diffuse among small-sized QDs (4 nm) due to the strong quantum confinement. On the other hand, both photoinduced electrons and holes in large-sized QDs (10 nm) would diffuse toward the interface with the small-sized QDs, followed by a recombination process. Combining the carrier diffusion study with a Monte Carlo simulation on the QD assembly in the mixture films, we can calculate the diffusion lengths of charge carriers to be similar to 239 +/- 16 nm in 10 nm CsPbBr3 QDs and the mobility values of electrons and holes to be 2.1 (+/- 0.1) and 0.69 (+/- 0.03) cm(2)/V s, respectively. Both parameters indicate an efficient charge carrier transport in DDAB-capped QD films, which rationalized the perfect performance of their LED device application. Workplace Institute of Plasma Physics Contact Vladimíra Kebza, kebza@ipp.cas.cz, Tel.: 266 052 975 Year of Publishing 2022 Electronic address https://pubs.acs.org/doi/pdf/10.1021/acsami.1c11676
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