First-principles study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:mi>Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>-related luminescence and traps in the perovskites <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ca</mml:mi><mml:mi>M</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mi>M</mml:mi><mml:mo>=</mml:mo><mml:mi>Zr</mml:mi><mml:mo>,</mml:mo><mml:mspace width="0.28em"/><mml:mi>Sn</mml:mi><mml:mo>,</mml:mo><mml:mspace width="0.28em"/><mml:mi>Ti</mml:mi></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:math>
Bibo Lou, Jun Wen, Jiajia Cai, Yau Yuen Yeung, Min Yin, Chang‐Kui Duan
Abstract
The ${\mathrm{Bi}}^{3+}$ ion is an excellent activator and sensitizer for luminescent materials. However, the complexity and variety of the ${\mathrm{Bi}}^{3+}$-related transitions bring a great challenge to the study of luminescence processes of ${\mathrm{Bi}}^{3+}$ doped materials. Here, we presented first-principles calculations to determine the excitation, relaxation, and emission processes of ${\mathrm{Bi}}^{3+}$ activated materials by using $\mathrm{Ca}M{\mathrm{O}}_{3}:{\mathrm{Bi}}^{3+}(M=\mathrm{Zr},\phantom{\rule{0.28em}{0ex}}\mathrm{Sn},\phantom{\rule{0.28em}{0ex}}\mathrm{Ti})$ as prototype systems, where ${\mathrm{Bi}}^{3+}$ substitutes ${\mathrm{Ca}}^{2+}$ in similar coordinate environments but presents tremendously different excitation and emission spectra. The equilibrium geometric structures of excited states were calculated based on density-functional theory (DFT), with appropriately constraining the electron occupation and including the spin-orbit couplings. Then the hybrid DFT calculations were carried out to obtain the electronic structures and defect levels. Different metastable excited states and Stokes shift were obtained for $M=\mathrm{Zr}$, Sn, and Ti, which explain the remarkable differences in the measured emission spectra. The energies of three types of transitions are obtained from the calculations, including intra-${\mathrm{Bi}}^{3+}$ bands transition and charge transfer between ${\mathrm{Bi}}^{3+}$ ions and the band edges. This leads to a clear and reliable interpretation of all the excitation spectra in the series. The method and its applications to $\mathrm{Ca}M{\mathrm{O}}_{3}:{\mathrm{Bi}}^{3+}$ show the potential of first-principles calculations in analyzing and predicting luminescent properties of ${\mathrm{Bi}}^{3+}$ activated materials.