反键分子轨道
价(化学)
材料科学
谱线
电子结构
原子轨道
结晶学
物理
凝聚态物理
电子
化学
量子力学
作者
T. Umebayashi,Keisuke Asai,Takashi Kondo,Aiko Nakao
出处
期刊:Physical review
日期:2003-04-15
卷期号:67 (15)
被引量:458
标识
DOI:10.1103/physrevb.67.155405
摘要
The electronic structures of three-dimensional and two-dimensional lead-halide-based crystals ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$ and $({\mathrm{C}}_{4}{\mathrm{H}}_{9}{\mathrm{NH}}_{3}{)}_{2}{\mathrm{PbI}}_{4}$ are investigated by photoelectron spectroscopy and band calculations using the linear combination of atomic orbitals within the density-functional theory. For both crystals, the top of the valence band is found to consist mainly of the $\ensuremath{\sigma}$-antibonding states of Pb $6s$ and I $5p$ orbitals, and the bottom of the conduction band to be composed primarily of the $\ensuremath{\sigma}$-antibonding states of Pb $6p$ and I $5s$ orbitals. Photoelectron spectra of the valence-band region indicate that the electronic structures change depending on the dimensionality of the crystals. Based on the calculation results, the differences observed in the spectra are rationalized in terms of narrowing bandwidth as the dimensionality decreases from three to two dimensions. It is shown that the bandwidth narrowing of the two-dimensional crystal is due to zero dispersion in the vertical direction and the Jahn-Teller effect in the layered structure. These effects lead to a wideband gap and high exciton stability in $({\mathrm{C}}_{4}{\mathrm{H}}_{9}{\mathrm{NH}}_{3}{)}_{2}{\mathrm{PbI}}_{4}.$
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