Recently, Professor Linsong Li's group reported the synthesis of high-quality alloyed CdSe1-xSxand CdSe/CdS core/shell QDs with controlled excited state properties by tuning the composition and shell. By applying this quantum dots into QLED with conventional device structure, so that the efficiency and brightness of the device have been greatly improved.
The as-prepared alloyed CdSeS core/shell QDs exhibit excellent optical properties, such as single-exponential PL decay dynamics, high purity (FWHM of 28 nm), and non-blinking emission by precise adjustment of the Se/S ratio. By applying the QDs into QLEDs, the best device displays a maximum luminance of 92,330 cd/m2, and an EQE of 14.5%. Importantly, the efficiency can still be sustained at more than 70% of the peak values in the range of 460-37,490 cd/m2. Such excellent performance is attributed to the appropriate composition tuning of the as-prepared alloyed QDs and subsequent relief of inner dot strain caused by the lattice mismatch and compensation of defects, which improve the efficiency of emissive recombination of excitons. ACS Applied Materials & Interfaces 2019, 11(6), 6238-6247.（SCI, IF=8.456）
Article link:https://doi.org/10.1021/acsami.8b17127
Next, shape anisotropic QDs have polarized light emission andhigh molar extinction coefficient different from the traditional spherical QDs, so we developed a two-step method to grow a thick rod-shape CdS shell onto CdSe core. The successful overgrowth of an additional CdS shell over the CdSe/CdS NRs led to the increase of PL quantum efficiencies up to 86%. The high maximum luminance and EQE can reach up to 104000 cd/m2and 15.7%. These exceptional values are at least 1.3-fold higher as compared to the highest values of luminance of 76000 cd/m2and EQE of 12% reported to date. Such excellent results are likely attributable to a unique structure in CdSe/CdS//CdS NRs with a relatively high QYs and thick CdS outer shell that minimizes nonradiative energy transfer between closely packed EML NRs. Optics Express, 2019, 27(6), 7935-7944.（SCI, IF=3.98）.
Article link:https://doi.org/10.1364/OE.27.007935
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