High-efficiency red electroluminescent device based on multishelled InP quantum dots

Abstract

We report on the synthesis of highly fluorescent red-emitting InP quantum dots (QDs) and their application to the fabrication of a high-efficiency QD-light-emitting diode (QLED). The core/shell heterostructure of the QDs is elaborately tailored toward a multishelled structure with a composition-gradient ZnSeS intermediate shell and an outer ZnS shell. Using the resulting InP/ZnSeS/ZnS QDs as an emitting layer, all-solution-processible red InP QLEDs are fabricated with a hybrid multilayered device structure having an organic hole transport layer (HTL) and an inorganic ZnO nanoparticle electron transport layer. Two HTLs of poly(9-vinlycarbazole) or poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4^'-(N-(4-sec-butylphenyl))diphenyl-amine), whose hole mobilities are different by at least three orders of magnitude, are individually applied for QLED fabrication and such HTL-dependent device performances are compared. Our best red device displays exceptional figures of merit such as a maximum luminance of 2849 cd/m², a current efficiency of 4.2 cd/A, and an external quantum efficiency of 2.5%.

Cadmium‐Free InP/ZnSeS/ZnS Heterostructure‐Based Quantum Dot Light‐Emitting Diodes with a ZnMgO Electron Transport Layer and a Brightness of Over 10 000 cd m−2

“…Quantum dots (QDs) can be used in many applications, such as light‐emitting diodes (LEDs), solar cells, and bioimaging . QD‐based LEDs are excellent candidates for next‐generation displays because of their advantages of high color saturation, simple fabrication, and good stability.…”

54‐5: New Technologies for Colouring in Displays

“…The main reason of these drawbacks is originated from electroluminescent (EL) quenching during the device operation by Auger recombination with charged carriers, strong electric field (i.e. field-induced quenching), and device degradation with thermal energy loss in organic charge transport layer or QD/organic interface defects [9][10][11][12]. Therefore, it is essential to use other device structure or inorganic charge transport materials to remove these fundamental issues.…”

P‐113: Ligand‐Dependent Stabilities and Optical Properties of InP / GaP / ZnS Quantum Dots

“…For example, multi-shelled QDs are successfully synthesized by inserting an intermediate layer such as ZnSe, ZnSeS, and GaP, and as a result, QY is significantly increased. [3][4][5] Another approach is to physically protect the quantum dots from the oxidative environment. Typically commercially available quantum dot films are produced by curing the resin in which the QDs are dispersed between the barrier films.…”