An efficient organic and inorganic hybrid interlayer for high performance inverted red cadmium-free quantum dot light-emitting diodes

Abstract

The efficiency and device lifetime of quantum dot light-emitting diodes (QLEDs) devices suffer due to charge unbalance issue resulting from excess electron injection from ZnO electron transport layer (ETL) to...

Stable ZnS Electron Transport Layer for High-Performance Inverted Cadmium-Free Quantum Dot Light-Emitting Diodes

“…This can be attributed to a spontaneous charge transfer process and/or an intra-gap-assisted non-radiative recombination process. 27 The sample with the glass/Zn 0.85 Mg 0.15 O/QD structure showed an increased average exciton lifetime from 32.5 to 37.3 ns. Similarly, when the ZnS ETL layer was placed between the ZnO and QD layers, the average exciton lifetime increased from 32.5 to 36.8 ns.…”

“…The J – V and L – V characteristics of QLEDs and the EQE and EL spectral measurements were obtained using the same equipment as that in our previous work . The TRPL, PL, and absorption spectra and AFM images of the films were measured using the same apparatus as that reported in our previous work . The thickness of functional films was measured by spectroscopic ellipsometry (HORIBA).…”

“…20 The TRPL, PL, and absorption spectra and AFM images of the films were measured using the same apparatus as that reported in our previous work. 27 The thickness of functional films was measured by spectroscopic ellipsometry (HORIBA). A Shimadzu X-ray diffractometer (XRD6000) having nickel-filtered Cu Kα radiation was used for structural analysis within the diffraction angles ranging from 10 to 160°.…”

“…27 The sol−gel ZnO and Zn 0.85 Mg 0.15 O solution were prepared similarly, as shown in our previous reports. 24,27 The ZnO precursor was first deposited on ITO for 60 s at 3000 rpm. Then, it was annealed for 60 min at 200 °C.…”

“…In this study, we report a stable inorganic material zinc sulfide (ZnS), which functions as a cascaded ETL when deposited on the top of ZnO. ZnS is a promising n-type semiconductor with a wide band gap of 3.4–3.8 eV and has a relatively low electron mobility (1.18 × 10 –6 cm 2 V –1 S –1 ) compared to the ZnO ETL (5.2 × 10 –4 cm 2 V –1 S –1 ). , In addition, ZnS is already used as a shell material in InP QDs, which can facilitate efficient electron injection to the QD layer. Moreover, ZnS does not contain any oxygen atoms in its crystal structure.…”