Blue-emitting CsI thin films

Xuan Huang; Xiaobing Tang; Xiyu Wen; Saurabh Singh; Y Lu; Fuqian Yang

doi:10.1016/j.jlumin.2025.121126

Blue-emitting CsI thin films

Xuan Huang, Xiaobing Tang, Xiyu Wen, Saurabh Singh, Y Lu, Fuqian Yang

Research output: Contribution to journal › Article › peer-review

Abstract

Cesium iodide (CsI) with a blue emission is a promising material for applications in optoelectronic and biomedical fields. However, the low-cost fabrication for CsI with a blue emission remains a challenge. In this work, a facile and green approach to prepare CsI thin films is demonstrated, in which deionized (DI) water makes it possible for non-luminescent CsI powder to form thin films with a blue emission of 415 nm at room temperature. The CsI crystals undergo a crystallization process during the evaporation of the aqueous solution, thus resulting in tensile lattice strain and reducing the bandgap of the CsI crystals. The density functional theory (DFT) calculation reveals that hydrostatic-tensile lattice strain leads to the decrease of the bandgap of CsI crystal. The as-prepared CsI thin films exhibit excellent optical stability that the photoluminescence intensity retains 85 % of initial one after one month in the air. This work is expected to move a step forward for the low-cost manufacturing of CsI films with low energy consumption for blue-emitting devices.

Original language	English
Article number	121126
Journal	Journal of Luminescence
Volume	280
DOIs	https://doi.org/10.1016/j.jlumin.2025.121126
State	Published - May 2025

Bibliographical note

Publisher Copyright:
© 2025 Elsevier B.V.

Funding

FY is grateful for the support by the NSF through the CBET-2018411 monitored by Dr. Nora F Savage. The authors are also grateful to Mr. You-lin Huang for providing the optical images of the CsI film and CsI powder over a period of 7 days and the life-time results.

Funders	Funder number
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China	CBET-2018411
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China

Keywords

Blue emission
CsI thin films
Optical stability
Water

ASJC Scopus subject areas

Biophysics
Atomic and Molecular Physics, and Optics
General Chemistry
Biochemistry
Condensed Matter Physics

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.jlumin.2025.121126

Cite this

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title = "Blue-emitting CsI thin films",

abstract = "Cesium iodide (CsI) with a blue emission is a promising material for applications in optoelectronic and biomedical fields. However, the low-cost fabrication for CsI with a blue emission remains a challenge. In this work, a facile and green approach to prepare CsI thin films is demonstrated, in which deionized (DI) water makes it possible for non-luminescent CsI powder to form thin films with a blue emission of 415 nm at room temperature. The CsI crystals undergo a crystallization process during the evaporation of the aqueous solution, thus resulting in tensile lattice strain and reducing the bandgap of the CsI crystals. The density functional theory (DFT) calculation reveals that hydrostatic-tensile lattice strain leads to the decrease of the bandgap of CsI crystal. The as-prepared CsI thin films exhibit excellent optical stability that the photoluminescence intensity retains 85 \% of initial one after one month in the air. This work is expected to move a step forward for the low-cost manufacturing of CsI films with low energy consumption for blue-emitting devices.",

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doi = "10.1016/j.jlumin.2025.121126",

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AU - Huang, Xuan

AU - Tang, Xiaobing

AU - Wen, Xiyu

AU - Singh, Saurabh

AU - Lu, Y

AU - Yang, Fuqian

PY - 2025/5

Y1 - 2025/5

N2 - Cesium iodide (CsI) with a blue emission is a promising material for applications in optoelectronic and biomedical fields. However, the low-cost fabrication for CsI with a blue emission remains a challenge. In this work, a facile and green approach to prepare CsI thin films is demonstrated, in which deionized (DI) water makes it possible for non-luminescent CsI powder to form thin films with a blue emission of 415 nm at room temperature. The CsI crystals undergo a crystallization process during the evaporation of the aqueous solution, thus resulting in tensile lattice strain and reducing the bandgap of the CsI crystals. The density functional theory (DFT) calculation reveals that hydrostatic-tensile lattice strain leads to the decrease of the bandgap of CsI crystal. The as-prepared CsI thin films exhibit excellent optical stability that the photoluminescence intensity retains 85 % of initial one after one month in the air. This work is expected to move a step forward for the low-cost manufacturing of CsI films with low energy consumption for blue-emitting devices.

AB - Cesium iodide (CsI) with a blue emission is a promising material for applications in optoelectronic and biomedical fields. However, the low-cost fabrication for CsI with a blue emission remains a challenge. In this work, a facile and green approach to prepare CsI thin films is demonstrated, in which deionized (DI) water makes it possible for non-luminescent CsI powder to form thin films with a blue emission of 415 nm at room temperature. The CsI crystals undergo a crystallization process during the evaporation of the aqueous solution, thus resulting in tensile lattice strain and reducing the bandgap of the CsI crystals. The density functional theory (DFT) calculation reveals that hydrostatic-tensile lattice strain leads to the decrease of the bandgap of CsI crystal. The as-prepared CsI thin films exhibit excellent optical stability that the photoluminescence intensity retains 85 % of initial one after one month in the air. This work is expected to move a step forward for the low-cost manufacturing of CsI films with low energy consumption for blue-emitting devices.

KW - Blue emission

KW - CsI thin films

KW - Optical stability

KW - Water

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Blue-emitting CsI thin films

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

UN SDGs

Access to Document

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