Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 10, Issue 49, Pages 42844-42855Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.8b15222
Keywords
semiconductor nanocrystals; quantum dots; I-III-VI2 semiconductor; multinary semiconductor; nonstoichiometry; band-edge photoluminescence; visible photoluminescence; wavelength tunability
Funding
- JSPS KAKENHI [JP26107014, JP17H05254, JP16H06507, JP16H06052, JP18H03927, JP18K19128, JP18H03863]
- Nichia Corp.
- MEXT Nanotechnology Platform [12024046]
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The nonstoichiometry of semiconductor I-III-VI semiconductor nanoparticles, especially the ratio of group Ito group III elements, has been utilized to control their physicochemical properties. We report the solution-phase synthesis of non-stoichiometric Ag-In-S and Ag-In-Ga-S nanoparticles and results of the investigation of their photoluminescence (PL) properties in relation to their chemical compositions. While stoichiometric AgInS2 nanoparticles simply exhibited only a broad PL band originating from defect sites in the particles, a narrow band edge PL peak newly appeared with a decrease in the Ag fraction in the nonstoichiometric Ag-In-S nano-particles. The relative PL intensity of this band edge emission with respect to the defect-site emission was optimal at a Ag/(Ag + In) value of ca. 0.4. The peak wavelength of the band edge emission was tunable from 610 to 500 nm by increased doping with Ga3+ into Ag-In-S nanoparticles due to an increase of the energy gap. Furthermore, surface coating of Ga3+-doped Ag-In-S nanoparticles, that is, Ag-In-Ga-S nanoparticles, with a GaSx shell drastically and selectively suppressed the broad defect-site PL peak and, at the same time, led to an increase in the PL quantum yield (QY) of the band edge emission peak. The optimal PL QY was 28% for Ag-In-Ga-S@GaSx core-shell particles, with green band-edge emission at 530 nm and a full width at half-maximum of 181 meV (41 nm). The observed wavelength tunability of the band-edge PL peak will facilitate possible use of these toxic-element-free I-III-VI-based nanoparticles in a wide area of applications.
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