Influence of dielectric confinement on excitonic nonlinearity in inorganic-organic layered semiconductors
Influence of dielectric confinement on excitonic nonlinearity in inorganic-organic layered semiconductors
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DOI：
10.1103/physrevb.71.205306
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发表时间：
2005-05
影响因子：
3.7
通讯作者：
M. Shimizu;J. Fujisawa;J. Ishi-Hayase
中科院分区：
文献类型：
--
作者：
M. Shimizu;J. Fujisawa;J. Ishi-Hayase
We have investigated photoinduced spectral changes of excitons in inorganic-organic layered semiconductors, ${({\mathrm{C}}_{6}{\mathrm{H}}_{5}{\mathrm{C}}_{2}{\mathrm{H}}_{4}{\mathrm{NH}}_{3})}_{2}\mathrm{Pb}{\mathrm{I}}_{4}\phantom{\rule{0.3em}{0ex}}(\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4})$ and ${({\mathrm{C}}_{6}{\mathrm{H}}_{13}{\mathrm{NH}}_{3})}_{2}{\mathrm{PbI}}_{4}\phantom{\rule{0.3em}{0ex}}(\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4})$, by means of the subpicosecond pump-probe spectroscopy. The two semiconductors consist of the same inorganic layers and different organic layers. In the two substances, the blueshift and the bleaching of the exciton are observed. It is found that both of the blueshift and the bleaching are considerably stronger in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$. The weight of the blueshift relative to the bleaching is larger in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$. These differences are qualitatively explained in terms of the stronger dielectric confinement in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ due to the lower dielectric constant of the organic layers in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$. Delay time dependences of the blueshift and the bleaching and their polarization dependences are understood as being due to the exciton relaxation in the angular momentum space with rates of 2.7 and $4.1\phantom{\rule{0.3em}{0ex}}{\mathrm{ps}}^{\ensuremath{-}1}$ for $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ and $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$, respectively.
We have investigated photoinduced spectral changes of excitons in inorganic-organic layered semiconductors, ${({\mathrm{C}}_{6}{\mathrm{H}}_{5}{\mathrm{C}}_{2}{\mathrm{H}}_{4}{\mathrm{NH}}_{3})}_{2}\mathrm{Pb}{\mathrm{I}}_{4}\phantom{\rule{0.3em}{0ex}}(\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4})$ and ${({\mathrm{C}}_{6}{\mathrm{H}}_{13}{\mathrm{NH}}_{3})}_{2}{\mathrm{PbI}}_{4}\phantom{\rule{0.3em}{0ex}}(\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4})$, by means of the subpicosecond pump-probe spectroscopy. The two semiconductors consist of the same inorganic layers and different organic layers. In the two substances, the blueshift and the bleaching of the exciton are observed. It is found that both of the blueshift and the bleaching are considerably stronger in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$. The weight of the blueshift relative to the bleaching is larger in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$. These differences are qualitatively explained in terms of the stronger dielectric confinement in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ due to the lower dielectric constant of the organic layers in $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ than in $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$. Delay time dependences of the blueshift and the bleaching and their polarization dependences are understood as being due to the exciton relaxation in the angular momentum space with rates of 2.7 and $4.1\phantom{\rule{0.3em}{0ex}}{\mathrm{ps}}^{\ensuremath{-}1}$ for $\mathrm{PhE}\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$ and $\mathrm{C}6\text{\ensuremath{-}}{\mathrm{PbI}}_{4}$, respectively.