Heterostructural tailoring of blue ZnSeTe quantum dots toward high-color purity and high-efficiency electroluminescence

Impact of Morphological Inhomogeneity on Excitonic States in Highly Mismatched Alloy ZnSe1–XTeX Nanocrystals

“…Interestingly, we find that the spectral shift results from an emergence of additional peaks at lower-energy positions, approximately >110 meV apart from the apex, rather than the gradual shift of the main peak, which is evident in asymmetric PL spectral profiles for NCs with non-zero Te content. In fact, the additional peaks on the lower-energy side of PL spectra have been commonly observed in ZnSe 1– X Te X -based NCs whose PL peak emission lies in the blue region [450–470 nm (2.64–2.76 eV)]. − This phenomenon is responsible for the sudden broadening of the spectral line width (fwhm) from 110 meV (16 nm) for X = 0 to 260 meV (44 nm) for X = 0.08.…”

“…Heavy metal-free ZnSe 1– X Te X alloy NCs are particularly interesting due to their wide emission tunability from violet to orange and near-unity photoluminescence quantum yields (PL QYs), with special emphasis on their potential for the blue emitter. − Blue emitters are the essence of everyday light-emitting applications, not only because blue is one of the primary colors but also because it is the energy source for the other color emitters via spectral down-conversion. In addition to the high efficiency and emission stability that are prerequisites, from a practical standpoint, blue emitters should be given with fine emission wavelength tunability for eye comfort as well as a narrow spectral line width for a wide color gamut. , Specifically, industrial standards for eye safety suggest limiting the use of high-energy blue emission to approximately greater than 2.8 eV (440 nm).…”

“…However, ZnSe 1– X Te X NCs show broad non-Gaussian emission spectra with multiple exponential decay dynamics even with near-unity PL QYs. Interestingly, but unfortunately, all of the previous reports show sudden line width broadening as the peak emission wavelength of ZnSe 1– X Te X NCs is tuned to the blue region [i.e., full width at half-maximum (fwhm) = 35–45 nm (210–270 meV) for NCs with peak PL at 450–470 nm (2.64–2.76 eV)], − which is 2–2.7 times higher than that of standard red or green heavy metal-free NCs implemented in LED applications [i.e., peak PL and fwhm for red InP NCs of 630 and 35 nm, respectively (1.97 eV and 109 meV, respectively) and green InP NCs of 530 and 35 nm, respectively (2.34 eV and 155 meV, respectively)], − imposing a roadblock toward their practical use in display applications. Most importantly, understanding the origin of unusual characteristics of these ZnSe 1– X Te X alloy NCs is lacking, as are future research directions.…”

Advances in Quantum Dot Printing Techniques for Light-Emitting Diode Applications

“…따라서, 양자점 디스플레이와 관련 된 많은 연구가 활발히 이루어지고 있으며, 산업계에 서도 양자점을 사용한 제품의 상용화가 진행되고 있다 [23]. 특히, 최근 전계발광 양자점 발광소자(quantum dot light-emitting diode, QLED)에 대해 이론적 한계에 육박하는 외부양자효율을 달성하기도 하였다 [24][25][26][27].…”

Localized surface plasmon-enhanced blue electroluminescent device based on ZnSeTe quantum dots and AuAg nanoparticles

“…Therefore, it is indispensable to find alternative Cd-free QDs with optical properties similar or superior to those of Cd-based counterparts. In this regard, III–V, II–VI and I–III–VI-based compositions such as InP, 4–8 ZnSeTe 9–14 and Cu–In–S, 15–19 respectively, have gained huge attention as possible candidates for the synthesis of Cd-free visible QD emitters. While a large number of QLEDs based on Cd-free QDs have been explored to date, only limited cases on blue devices have been reported as compared with green and red ones.…”