Tailored Photoluminescence Properties of Ag(In,Ga)Se₂ Quantum Dots for Near-Infrared In Vivo Imaging

Abstract

Multinary semiconductor quantum dots (QDs) that have less toxicity and show near-infrared light responsivity have attracted much attention for in vivo bioimaging. In this study, we controlled the optical properties of Ag–In–Se QDs by modulating the nonstoichiometry and the degree of Ga3+ doping. Precise tuning of the Ag/In ratio of Ag–In–Se QDs enabled a sharp band-edge emission to emerge without broad defect-site emission. Ga3+ doping into Ag–In–Se (AIGSe) QDs enlarged their energy gap, resulting in a blue shift of the band-edge PL peak from from 890 to 630 nm. The band-edge PL intensity was remarkably enlarged by surface coating with a thin GaS x shell followed by treatment with trioctylphosphine, the highest PL yield being 38% for the PL peak at 800 nm. Thus-obtained QDs were successfully used as near-IR PL probes for three-dimensional in vivo bioimaging in which the wavelengths of excitation and detection lights could be selected in the first biological window, and then the signals were clearly detected from AIGSe@GaS x core–shell QDs injected into biological tissues by ca. 5 mm in depth.

Surface ligand chemistry on quaternary Ag(InxGa1−x)S2 semiconductor quantum dots for improving photoluminescence properties

“…Recently, I 2 -VI, III-V and I-III-VI 2 semiconductors have emerged as candidate materials for cadmiumfree QDs, [1][2][3] and they are usable in a variety of applications, including photovoltaics, [4][5][6] light-emitting devices, 1,7-10 and bioimaging. 3,[11][12][13] The emission color of these QDs can be engineered by tuning their bandgap energy (E g ) via their size; this is one of the unique characteristics of QDs, which is referred to as the quantum size effect. [14][15][16] Furthermore, the bandgaps of I-III-VI 2 semiconductors, a group that includes silver indium sulde (AgInS 2 ), copper indium sulde (CuInS 2 ), and their selenide derivatives, can also be controlled by adjusting their chemical composition and creating alloys from these materials.…”

Ag2ZnSnS4–ZnS core–shell colloidal quantum dots: a near-infrared luminescent material based on environmentally friendly elements

“…Consequently, there is an increased effort towards the development of heavy metal-free RoHS compliant low-cost luminescence phosphors as an alternative. 6 As a result indium/gallium based III-V group QDs such as InAs, InSb, GaAs [7][8][9][10] and I-III-VI group QDs such as CuIn(S/Se) 2 , AgIn(Se/ Te) 2 [11][12][13][14] with NIR emission have attracted significant interest.…”

“…Core-shell heterostructures of various binary and ternary QDs that emit NIR PL have been studied in the previous literature. 6,9,10,12 However, core-shell heterostructures of quaternary QDs have rarely been explored 27,28 due to synthetic impediments. Herein, we present the thiol free synthesis of bright tunable NIR luminescent AZTS-ZnS core-shell QDs with controlled growth of shell thickness.…”

Ultra-small aqueous glutathione-capped Ag–In–Se quantum dots: luminescence and vibrational properties

“…20,21 The most popular way towards luminescent AISe and Zndoped AISe QDs is the incorporation of In 3+ into primary Ag 2 Se particles that can be achieved by relatively hightemperature hot-injection syntheses in coordinating solvents (such as trioctylphosphine or oleylamine). 9,10,15,20,[22][23][24][25][26][27][28][29][30][31][32] Typically, Se 0 is used as selenide precursor in these syntheses but sometimes rather exotic Se precursors are introduced to achieve ne control over the nucleation and growth of AISe QDs, such as bis(trimethylsilyl)selenide, 33 cyclohexeno-selenodiazole, 21,30 or Li[N(SeMe 3 ) 2 ]. 34 In the latter case, both composition and size of the AISe QDs can be independently varied resulting in "core" AISe and "core/shell" AISe/ZnSe QDs with a size from 2.4 nm to around 7 nm and three distinctly different compositions, Ag 3 -In 5 Se 9 , AgIn 3 Se 5 , and AgIn 11 Se 17 , while a top PL QY of 73% is observed for Ag 3 In 5 Se 9 cores with relatively thick ZnSe shells.…”