Abstract
We developed a three-step colloidal synthesis of near-infrared (NIR) active Cu–In–Se (CISe)-based nanocrystals (NCs) via a sequential partial cation exchange realized in one pot. In the first step, binary highly copper deficient Cu2–xSe NCs were synthesized, followed by a partial cation exchange of copper to indium ions, yielding CISe NCs. This reaction allows for a precise control of the composition of the resulting NCs through a simple variation of the ratio between guest-cation precursors and parent NCs. To enhance the stability and the photoluminescence (PL) properties of the NCs, a subsequent ZnS shell was grown in the third step, resulting in CISeS/ZnS core/shell particles. These core/shell hetero-NCs exhibited a dramatic increase in size and a restructuring to trigonal pyramidal shape. The shell growth performed at a relatively high temperature (250 °C) also led to anion exchange, in which sulfur replaced part of selenium atoms close to the surface of the NCs, forming alloyed CISeS core structure. ...
Highlights
Colloidal semiconductor nanocrystals (NCs) have gained increasing scientific attention due to their unique size- and shape-dependent optoelectronic properties dictated by quantum confinement.[1−3] They hold a huge potential as materials to be employed in optoelectronic devices as well as in the field of biomedicine.[3−5] So far, the study of the semiconductor NCs has mainly focused on binary II−VI, IV−VI, and to some extent on III−V compounds, MX (M2+ Cd2+, Hg2+, Pb2+; M3+ In3+; X2− S2−, Se2−, Te2−; X3− P3−), which are promising for optoelectronic and photovoltaic applications.[6−8]Despite their advantages, they contain toxic elements, which can be hazardous when released to the environment
In the past decades, the focus of research has broadened out on copper chalcogenide-based ternary and quaternary compounds, e.g. CuInS(Se)[2] (CIS(Se)), Cu−Zn− In−S(Se) (CZIS(Se)), and Cu2ZnSnS(Se)[4] (CZTS(Se)), which have proven themselves as outstanding alternatives to the II−VI and IV−VI families of semiconductor nanoparticles.[9−11] An advantage of these materials consists in their low toxicity, giving them permission to widen the range of applications
Thereafter, In3+ ions were incorporated into these Cu2−xSe NCs, forming ternary CISe nanoparticles by means of a partial cation exchange (CE) reaction, i.e. a replacement of a part of the host copper cations by the guest indium cations in the crystal structure
Summary
Colloidal semiconductor nanocrystals (NCs) have gained increasing scientific attention due to their unique size- and shape-dependent optoelectronic properties dictated by quantum confinement.[1−3] They hold a huge potential as materials to be employed in optoelectronic devices as well as in the field of biomedicine.[3−5] So far, the study of the semiconductor NCs has mainly focused on binary II−VI, IV−VI, and to some extent on III−V compounds, MX (M2+ Cd2+, Hg2+, Pb2+; M3+ In3+; X2− S2−, Se2−, Te2−; X3− P3−), which are promising for optoelectronic and photovoltaic applications.[6−8]. By employing bis(trimethylsilyl)selenide as a chalcogenide precursor at relatively high temperatures (280−360 °C), Allen et al demonstrated the synthesis of 2−6 nm CISe NCs.[35] Nose et al synthesized 1.2− 5.6 nm CISe NCs at 320 °C, whose emission shifted from 838 to 918 nm with increasing reaction time.[45] For the purpose of in vivo imaging, Cassette et al developed a one-pot synthetic route, yielding CISe/ZnS NCs with PL spectra tunable from 700 to 1000 nm depending on the particle size (from ∼2 to ∼5 nm in diameter).[12] Zhong et al prepared ∼3.4 nm CISe NCs at moderate temperatures (≤200 °C), which exhibited emission in the red and the NIR region (∼600−850 nm).[26]. 0.02 mW to avoid sample heating under the microscope objective (100× for 514.7 nm and 40× for 325 nm excitation)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
