Thermal Stability of Semiconductor Nanocrystal Solids: Understanding Nanocrystal Sintering and Grain Growth

Wenyong Liu, Vishwas Srivastava, J. Matthew Kurley, Chengyang Jiang, Dmitri V. Talapin

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Nanomaterials are naturally metastable with respect to bulk solids. This raises the very important fundamental problem of their morphological stability, especially when nanoscale crystallites are touching or nearly touching each other, such as in thin-film devices. In some cases, nanostructuring must be preserved under operational conditions (e.g., in quantum dot LEDs, lasers, photodetectors, and nanogranular thermoelectric devices). In other cases, we use nanocrystalline particles as precursors to a material with large crystalline grains and aim to sinter them as efficiently as possible (e.g., in polycrystalline thin-film solar cells). We carried out a systematic study of sintering and grain growth in materials composed of various sub-10 nm semiconductor grains. The boundaries between individual semiconductor grains have been chemically engineered using inorganic surface ligands. We found that the early stages of sintering and grain growth of nanocrystalline semiconductors are controlled by the ion mobility at the nanocrystal surfaces, while the late stages of grain growth are controlled by the mobility of the grain boundaries. This appears to be a general phenomenon for semiconductor nanocrystals, and it leads to several interesting and counterintuitive trends. For example, III-V InAs nanocrystals are generally much more resilient against sintering and grain growth compared to II-VI CdSe nanocrystals even though bulk CdSe has significantly higher melting point temperature than InAs (1268 °C vs 942 °C). Grain growth can be dramatically accelerated when coupled to solid-solid phase transitions. These findings expand our toolbox for rational design of nanocrystal materials for different applications.

Original languageEnglish
Pages (from-to)21136-21148
Number of pages13
JournalJournal of Physical Chemistry C
Volume126
Issue number49
DOIs
StatePublished - Dec 15 2022
Externally publishedYes

Funding

We thank Andrew Nelson for editing the manuscript. This work on the synthesis and functionalization of nanomaterials was supported by the Center for Hierarchical Materials Design (CHiMad) supported by the U.S. Department of Commerce, National Institute of Standards and Technology, under financial assistance award number 70NANB14H012. The sintering and grain growth kinetics studies were supported by the National Science Foundation under award number DMR-2004880. V.S. was supported by the University of Chicago Materials Research Science and Engineering Center, which is funded by the National Science Foundation under award number DMR-2011854. This research used resources of the Center for Nanoscale Materials, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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