Depressed Phase Transitions and Thermally Persistent Local Distortions in CsPbBr3 Quantum Dots
The optoelectronic properties of CsPbX3 quantum dots (where X = Cl, Br, or I) are influenced by both their local and average structures. Variable-temperature synchrotron X-ray diffraction measurements of CsPbBr3 quantum dots show that the temperatures for both the orthorhombic-to-tetragonal (50 °C < Tγ-β < 59 °C) and tetragonal-to-cubic (108 °C < Tβ-α < 117 °C) phase transitions of the average structure are depressed relative to their temperatures in bulk CsPbBr3. Simultaneously, pair distribution function (PDF) analysis of syn-chrotron X-ray total scattering measurements indicate that the local crystal structure of the quantum dots is best described as ortho-rhombically distorted over the temperature range of 22 °C < T < 160 °C, with only small changes in the magnitude of the distortion occurring during the observed changes in the average structure. Here, taken together these results suggest that phase transitions in CsPbBr3 quantum dots are order-disorder, involving the gradual ordering of individually coherent domains that cannot be attributed to changes in the surface area or to ferroelectric phenomena.
- Research Organization:
- Univ. of Southern California, Los Angeles, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0006812; FG02-11ER4682; AC02-06CH11357; DMR 1720256
- OSTI ID:
- 1582648
- Journal Information:
- Chemistry of Materials, Vol. 30, Issue 19; ISSN 0897-4756
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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