Color-Tunable Highly Bright Photoluminescence of Cadmium-Free Cu-Doped Zn–In–S Nanocrystals and Electroluminescence

Abstract

A series of Cu doped Zn–In–S quantum dots (Cu:Zn–In–S d-dots) were synthesized via a one-pot noninjection synthetic approach by heating up a mixture of corresponding metal acetate salts and sulfur powder together with dodecanethiol in oleylamine media. After overcoating the ZnS shell around the Cu:Zn–In–S d-dot cores directly in the crude reaction solution, the resulting Cu:Zn–In–S/ZnS d-dots show composition-tunable photoluminescence (PL) emission over the entire visible spectral window and extending to the near-infrared spectral window (from 450 to 810 nm), with the highest PL quantum yield (QY) up to 85%. Importantly, the initial high PL QY of the obtained Cu:Zn–In–S/ZnS d-dots in organic media can be preserved when transferred into aqueous media via ligand exchange. Furthermore, electroluminescent devices with good performance (with a maximum luminance of 220 cd m–2, low turn-on voltages of 3.6 V) have been fabricated with the use of these Cd-free low toxicity yellow-emission Cu:Zn–In–S/ZnS d-dots as an active layer in these QD-based light-emitting diodes.

Large-scale synthesis of single-source, thermally stable, and dual-emissive Mn-doped Zn–Cu–In–S nanocrystals for bright white light-emitting diodes

“…For example, the emission spectra of Zn-Cu-In-S NCs are totally same to that of Cu doped CuInS2, indicating that they have the same recombination mechanism after some excitation wavelength. Therefore, the recombination path in multiry NCs involves an intrinsic defect, most likely associated with a copper centre, as shown in various works reported in literature [101][102][103][104]. In contrast to the studied Mn:ZnSe doped system, the emission of Mn-doped NCs showed extremely high thermal stability, which was consistent with the nature of the emission of the inner core states (d orbitals split by the crystal field) and not coupled with the lattice phonons.…”

“…When the sample was cooled to room temperature, the emission intensity was almost recovered. Normally, the emission for quaternary NCs was associated with the Cu energy level, and should be less coupled with lattice vibration in comparison with the excitonic emission of un-doped NCs [101]. In other words, the emission mechanism of multinary is much different from that of typical NCs with band gap emission.…”

“…A number of research groups focused on composition--dependent band gap tuning in alloy NCs and great success had been achieved [97][98][99][100][101][102]. For example, the PL peak position is tunable in the visible region by changing the ratio of Cu/Zn [31,[100][101][102]. Therefore, we can tune the composition of host materials as Nano Res.…”

From Binary Cu2S to Ternary Cu–In–S and Quaternary Cu–In–Zn–S Nanocrystals with Tunable Composition via Partial Cation Exchange

“…16 Therefore, as a next step after Cu + →In 3+ partial exchange yielding CIS NCs, we performed a second partial CE reaction with the incorporation of zinc, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 10 similar to the method reported by Zhang et al 19 In this approach, the zinc precursor was injected at 100 o C in the crude reaction mixture right after Cu + →In 3+ exchange. We note that the addition of octylamine (OctAm) by preparation of Zn-precursor improves solubilization of zinc salt yielding stable solutions without formation of gels, as has been observed by using solely OlAm as a ligand.…”

Liquid–Liquid Diffusion‐Assisted Crystallization: A Fast and Versatile Approach Toward High Quality Mixed Quantum Dot‐Salt Crystals

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2638www.MaterialsViews.com wileyonlinelibrary.com approaches, [ 15,16 ] effi ciency, [ 17,18 ] extending their spectral range [19][20][21] and environmental friendliness using less toxic materials [22][23][24] sparked industrial applications. Those started with the demonstration of a 40 in.

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