Kameyama Tatsuya, Kishi Marino, Miyamae Chie, Sharma Dharmendar Kumar, Hirata Shuzo, Yamamoto Takahisa, Uematsu Taro, Vacha Martin, Kuwabata Susumu, Torimoto Tsukasa
Graduate School of Engineering , Nagoya University , Chikusa-ku, Nagoya 464-8603 , Japan.
Department of Materials Science and Engineering , Tokyo Institute of Technology , 2-12-1 Ookayama , Meguro, Tokyo 152-8552 , Japan.
ACS Appl Mater Interfaces. 2018 Dec 12;10(49):42844-42855. doi: 10.1021/acsami.8b15222. Epub 2018 Dec 3.
The nonstoichiometry of I-III-VI semiconductor nanoparticles, especially the ratio of group I to group III elements, has been utilized to control their physicochemical properties. We report the solution-phase synthesis of nonstoichiometric 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 AgInS 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 nanoparticles. 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 Ga into Ag-In-S nanoparticles due to an increase of the energy gap. Furthermore, surface coating of Ga-doped Ag-In-S nanoparticles, that is, Ag-In-Ga-S nanoparticles, with a GaS 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@GaS 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.
I-III-VI族半导体纳米颗粒的非化学计量比，尤其是I族与III族元素的比例，已被用于控制其物理化学性质。我们报道了非化学计量比的Ag-In-S和Ag-In-Ga-S纳米颗粒的溶液相合成，以及它们的光致发光（PL）性质与其化学成分关系的研究结果。化学计量比的AgInS纳米颗粒仅表现出源于颗粒缺陷位点的宽PL带，而非化学计量比的Ag-In-S纳米颗粒中，随着Ag含量的降低，新出现了一个窄的带边PL峰。该带边发射相对于缺陷位点发射的相对PL强度在Ag/(Ag + In)值约为0.4时最佳。由于能隙增加，通过向Ag-In-S纳米颗粒中增加Ga掺杂，带边发射的峰值波长可从610 nm调谐至500 nm。此外，用GaS壳层对掺杂Ga的Ag-In-S纳米颗粒（即Ag-In-Ga-S纳米颗粒）进行表面包覆，可显著且选择性地抑制宽的缺陷位点PL峰，同时导致带边发射峰的PL量子产率（QY）增加。Ag-In-Ga-S@GaS核壳颗粒的最佳PL QY为28%，在530 nm处有绿色带边发射，半高宽为181 meV（41 nm）。观察到的带边PL峰的波长可调性将有助于这些无有毒元素的I-III-VI基纳米颗粒在广泛的应用领域中得到应用。
