scholarly journals First-principles study ofCe3+-dopedlanthanum silicate nitride phosphors: Neutral excitation, Stokes shift, and luminescent center identification

2016 ◽  
Vol 93 (15) ◽  
Author(s):  
Yongchao Jia ◽  
Anna Miglio ◽  
Samuel Poncé ◽  
Xavier Gonze ◽  
Masayoshi Mikami
Keyword(s):  
First Principles ◽  
Stokes Shift ◽  
Luminescent Center ◽  
First Principles Study

Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

2019 ◽  
Author(s):  
Young-Kwang Jung ◽  
Joaquin Calbo ◽  
Ji-Sang Park ◽  
Lucy D. Wahlley ◽  
Sunghyun Kim ◽  
...  
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Stokes Shift ◽  
Green Luminescence ◽  
Counter Ions ◽  
Self Consistent ◽  
Deep Ultraviolet ◽  
Halide Perovskite ◽  
Related Compounds ◽  
Level Analysis

Cs<sub>4</sub>PbBr<sub>6 </sub>is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr<sub>6</sub><sup>4-</sup> octahedra with Cs<sup>+</sup> counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs<sub>4</sub>PbBr<sub>6</sub>. We find a heavily compensated system where the room-temperature carrier concentrations (< 10<sup>9</sup> cm<sup>-3</sup>) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br<sub>3</sub>) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission. <br>

Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

2019 ◽  
Author(s):  
Young-Kwang Jung ◽  
Joaquin Calbo ◽  
Ji-Sang Park ◽  
Lucy D. Wahlley ◽  
Sunghyun Kim ◽  
...  
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Stokes Shift ◽  
Green Luminescence ◽  
Counter Ions ◽  
Self Consistent ◽  
Deep Ultraviolet ◽  
Halide Perovskite ◽  
Related Compounds ◽  
Level Analysis

Cs<sub>4</sub>PbBr<sub>6 </sub>is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr<sub>6</sub><sup>4-</sup> octahedra with Cs<sup>+</sup> counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs<sub>4</sub>PbBr<sub>6</sub>. We find a heavily compensated system where the room-temperature carrier concentrations (< 10<sup>9</sup> cm<sup>-3</sup>) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br<sub>3</sub>) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission. <br>

Strain tuned high thermal conductivity in boron phosphide at nanometer length scales – a first-principles study

2020 ◽  
Vol 22 (36) ◽  
pp. 20914-20921 ◽  
Author(s):  
Rajmohan Muthaiah ◽  
Jivtesh Garg
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
High Thermal Conductivity ◽  
Biaxial Strain ◽  
Length Scales ◽  
First Principles Study ◽  
Boron Phosphide

We report novel pathways to significantly enhance the thermal conductivity at nanometer length scales in boron phosphide through biaxial strain.

First-principles study of two-dimensional bilayer GaN: structure, electronic properties and temperature effect

2019 ◽  
Vol 58 (SC) ◽  
pp. SCCB35 ◽  
Author(s):  
Tomoe Yayama ◽  
Anh Khoa Augustin Lu ◽  
Tetsuya Morishita ◽  
Takeshi Nakanishi
Keyword(s):  
Temperature Effect ◽  
Electronic Properties ◽  
First Principles ◽  
Two Dimensional ◽  
First Principles Study
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