Journal
CHEMISTRY OF MATERIALS
Volume 28, Issue 23, Pages 8622-8630Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.6b03555
Keywords
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Funding
- National Science Foundation [1411192, ACI-1053575]
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1411192] Funding Source: National Science Foundation
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In this work, we performed a systematic investigation of structure-composition-property relationships in Eu2+-activated beta-SiAlON, one of the most promising narrow-band green phosphors for high-power light-emitting diodes and liquid crystal display backlighting with wide color gamut. Using first-principles calculations, we identified and confirmed various chemical rules for Si-Al, O-N, and Eu activator ordering within the beta-SiAlON structure. Through the construction of energetically favorable models based on these chemical rules, we studied the effect of oxygen content and Eu2+ activator concentrations on the local EuN9 activator environment, and its impact on important photoluminescence properties such as emission peak position (using the band gap as a proxy), bandwidth, and thermal quenching resistance. Increasing oxygen content is shown to lead to an increase in Eu-N bond lengths and distortion of the EuN9 coordination polyhedron, modifying the crystal field environment of the Eu2+ activator, and resulting in red-shifting and broadening of the emission. We also show that the calculated excited band structure of beta-SiAION exhibits a large gap between the 5d levels and the conduction band of the host, indicating a large barrier toward thermal ionization (>0.5 eV) and, hence, excellent thermal quenching stability. Based on these insights, we discuss potential strategies for further composition optimization of beta-SiAlON.
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