A First-Principles Explanation of the Luminescent Line Shape of SrLiAl₃N₄:Eu²⁺ Phosphor for Light-Emitting Diode Applications

White light-emitting diodes are gaining popularity and are set to become the most common light source in the U.S. by 2025. However, their performance is still limited by the lack of an efficient red-emitting component with a narrow band emission. The red phosphor SrLiAl3N4:Eu2+ is among the first promising phosphors with a small bandwidth for next-generation lighting, but the microscopic origin of this narrow emission remains elusive. In the present work, density functional theory, the ΔSCF-constrained occupation method, and a generalized Huang–Rhys theory are used to provide an accurate description of the vibronic processes occurring at the two Sr2+ sites that the Eu2+ activator can occupy. The emission band shape of Eu(Sr1), with a zero-phonon line at 1.906 eV and a high luminescence intensity, is shown to be controlled by the coupling between the 5dz2–4f electronic transition and the low-frequency phonon modes associated with the Sr and Eu displacements along the Sr channel. The good agreement between our computations and experimental results allows us to provide a structural assignment of the observed total spectrum. By computing explicitly the effect of the thermal expansion on zero-phonon line energies, the agreement is extended to the temperature-dependent spectrum. These results provide insight into the electron–phonon coupling that accompanies the 5d–4f transition in similar UCr4C4-type phosphors. Furthermore, these results highlight the importance of the Sr channel in shaping the narrow emission of SrLiAl3N4:Eu2+, and they shed new light on the structure–property relations of such phosphors

High-Throughput Design of Non-oxide p‑Type Transparent Conducting Materials: Data Mining, Search Strategy, and Identification of Boron Phosphide

High-performance p-type transparent conducting materials (TCMs) are needed in a wide range of applications ranging from solar cells to transparent electronics. p-type TCMs require a large band gap (for transparency), low hole effective mass (for high mobility), and hole dopability. It has been demonstrated that oxides have inherent limitations in terms of hole effective masses making them difficult to use as a high-performance p-type TCM. In this work, we use a high-throughput computational approach to identify novel, non-oxide, p-type TCMs. By data mining a large computational data set (more than 30,000 compounds), we demonstrate that non-oxide materials can lead to much lower hole effective masses but to the detriment of smaller gaps and lower transparencies. We propose a strategy to overcome this fundamental correlation between low effective mass and small band gap by exploiting the weak absorption for indirect optical transitions. We apply this strategy to phosphides and identify zinc blende boron phosphide (BP) as a very promising candidate. Follow-up computational studies on defects formation indicate that BP can also be doped p-type and potentially n-type as well. Our work demonstrates how high-throughput computational design can lead to identification of materials with exceptional properties, and we propose a strategy to open the design of TCMs to non-oxide materials

High-Mobility Bismuth-based Transparent <i>p</i>‑Type Oxide from High-Throughput Material Screening

High-Mobility Bismuth-based Transparent <i>p</i>‑Type Oxide from High-Throughput Material Screenin