Performance Enhancement of Quantum Dot Light-Emitting Diodes via Surface Modification of the Emitting Layer

Abstract

CdSe-based quantum dots (QDs) have increasingly become important QDs for emerging display material because of their suitable bandgap, controllable size, and high PLQY. However, there are still many problems with CdSe QD films, including severe fluorescence quenching and low conductivity. Herein, we replace the long insulated oleic acid ligand with the shorter thiol ligand to enhance the mobility of charge carriers. It was found that the QDs with octanethiol in a quantum dot light-emitting diode (QLED) exhibited higher conductivity and lower turn-on voltage. Moreover, the defects on the surface of the QD layer were effectively passivated by adding a thin layer of cesium carbonate, and the radiation recombination of the quantum dot light-emitting layer was also significantly improved. It was evident that the performance of the optimized QLED device was improved with a peak luminance of 166 300−294 500 cd/m 2 and a peak current efficiency of 10−32 cd/A. Thus, the current work provides two ways to optimize QD films and proposes a method to improve the performance of QLEDs.

CdTe/Silica Nanospheres in a Lateral Flow Immunoassay for Prostate-Specific Antigen

“…For QDs of the same emission wavelength grown in situ, the time was the same, but the degree of surface reshaping of DMSN was different, possibly due to differences in the size and pore width of DMSN. For large-sized nanoparticles, the increased concentration of QDs within individual nanoparticles, which may lead to nonradiative energy transfer between QDs, 38 and the absence of the SiO 2 protective layer may ultimately lead to a decrease in fluorescence intensity by exploring the PL QYs and optical properties of four-sized UQSNs (Table S1 and Figure S6).…”

Interfacial Charge Modulation: An Efficient Strategy for Stable Blue Quantum‐Dot Light‐Emitting Diodes

“…[10] The fast decay process represents nonradiative recombination and related to the quenching of free carriers at the interface, whereas the slow decay process is assigned to radiative recombination and related to the emission. [24] By fitting the exciton lifetime with two-exponential model (summarized in Table S1, Supporting Information), the radiative recombination ratio increases significantly with the addition of Ti 3 C 2 T x . It is noted that the Ti 3 C 2 T x significantly increase radiative recombination, which could be attributed to the modulation of the interfacial charge.…”

Interfacial Passivation Engineering for Highly Efficient Quantum Dot Light-Emitting Diodes via Aromatic Amine-Functionalized Dipole Molecules

“…11 The interaction between dipole layers and QD films was also researched by X-ray photoelectron spectroscopy (XPS) suggesting that masses of OA ligands have been replaced with the dipolar molecules. 22,30 This will increase the QD overall performance such as optical properties and stability, as OA ligands readily shed from the surface of QDs, inducing dangling bonds, surface defect states, or even QD aggregation.…”

“…To further clear this point, we carried out Fourier transform infrared spectroscopy (FTIR) as shown in Figure d. The carbon–oxygen (COO – ) bond stretching frequency at 1550 and 1454 cm –1 , C–H stretching vibrations signals of the methylene (CH 2 ) at 2931 and 2854 cm –1 in OA is significantly lessened, suggesting that masses of OA ligands have been replaced with the dipolar molecules. , This will increase the QD overall performance such as optical properties and stability, as OA ligands readily shed from the surface of QDs, inducing dangling bonds, surface defect states, or even QD aggregation.…”