Chapter 13
Controlling Optical Properties
of Multinary Quantum Dots
for Developing Novel
Photoelectrochemical Reactions
Tsukasa Torimoto and Tatsuya Kameyama
Abstract We introduce solution-phase preparation of multinary QDs composed
of less-toxic Ag-III-VI-based semiconductors and control of their physicochemical
properties. The energy gaps (E g s) of multinary QDs could be adjusted by the chemical
composition as well as by the particle size. The photochemical properties, including
photoluminescence (PL), photocatalysis, and photocurrent generation, of prepared
QDs, are discussed in terms of the E g , the non-stoichiometric chemical composition,
and the particle morphology. The PL peak was controlled from visible to nearIR wavelength regions by varying the chemical composition of QDs, in which the
peak width of Ag-In-Ga-S QDs was remarkably narrowed by the removal of deep
defect levels via tuning of non-stoichiometry and the surface condition. A nonlinear
photoresponse induced by hot hole transfer was observed by visible light irradiation
to near-IR-light-responsive Zn-Ag-In-Te QDs. The findings will provide new insights
into design and fabrication of novel QD-based devices.
Keywords Quantum dot · Multinary semiconductor · Photoluminescence ·
Photocatalyst · Photocurrent generation · Hot hole transfer
13.1 Introduction
Quantum dots (QDs) are semiconductor nanocrystals with sizes of less than ca.
10 nm that show the quantum size effect. Their physicochemical properties are intermediate between those of molecules and bulk materials and strongly depend on their
particle size and shape. Many efforts have been devoted to the development of highefficient light energy conversion systems consisting of QDs as components, such
as photocatalysts and solar cells, because QDs have high absorption coefficients in
the visible and near-IR wavelength regions and their E g s are tunable depending on
the nanocrystal size [1, 2]. Recently, unique photoresponses originating from the
T. Torimoto (B) · T. Kameyama
Department of Materials Chemistry, Graduate School of Engineering, Nagoya University,
Chikusa-Ku, Nagoya 464-8603, Japan
e-mail: torimoto@chembio.nagoya-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_13
223
Controlling Optical Properties
of Multinary Quantum Dots
for Developing Novel
Photoelectrochemical Reactions
Tsukasa Torimoto and Tatsuya Kameyama
Abstract We introduce solution-phase preparation of multinary QDs composed
of less-toxic Ag-III-VI-based semiconductors and control of their physicochemical
properties. The energy gaps (E g s) of multinary QDs could be adjusted by the chemical
composition as well as by the particle size. The photochemical properties, including
photoluminescence (PL), photocatalysis, and photocurrent generation, of prepared
QDs, are discussed in terms of the E g , the non-stoichiometric chemical composition,
and the particle morphology. The PL peak was controlled from visible to nearIR wavelength regions by varying the chemical composition of QDs, in which the
peak width of Ag-In-Ga-S QDs was remarkably narrowed by the removal of deep
defect levels via tuning of non-stoichiometry and the surface condition. A nonlinear
photoresponse induced by hot hole transfer was observed by visible light irradiation
to near-IR-light-responsive Zn-Ag-In-Te QDs. The findings will provide new insights
into design and fabrication of novel QD-based devices.
Keywords Quantum dot · Multinary semiconductor · Photoluminescence ·
Photocatalyst · Photocurrent generation · Hot hole transfer
13.1 Introduction
Quantum dots (QDs) are semiconductor nanocrystals with sizes of less than ca.
10 nm that show the quantum size effect. Their physicochemical properties are intermediate between those of molecules and bulk materials and strongly depend on their
particle size and shape. Many efforts have been devoted to the development of highefficient light energy conversion systems consisting of QDs as components, such
as photocatalysts and solar cells, because QDs have high absorption coefficients in
the visible and near-IR wavelength regions and their E g s are tunable depending on
the nanocrystal size [1, 2]. Recently, unique photoresponses originating from the
T. Torimoto (B) · T. Kameyama
Department of Materials Chemistry, Graduate School of Engineering, Nagoya University,
Chikusa-Ku, Nagoya 464-8603, Japan
e-mail: torimoto@chembio.nagoya-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_13
223