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

Abstract

between quantum dot (QD)/ETL and QD/ hole transport layer (HTL), which is considered to be the major reason for the poor performance of device. [3] Metallic element doping has been verified to be the valid method for tuning the mobility of ZnO, which is able to alleviate the charge injection imbalance. In particular, Mgdoping has been primarily used for the high-performance red and green QLEDs. [4] It seems to be that single metallic element Mg doping is hard to improve the performance of B-QLEDs. Guo et al. used water as the passivation reagent to modify the ZnMgO to realize the high performance of B-QLED. [5] The functional layer of the device is very sensitive to water, which is detrimental to the stability of the device. Therefore, how to alleviate the charge accumulation at the QD/ETL interface still deserves more investigations. Promoting the exciton recombination through manipulating interfacial charge properties has been believed to be an effective strategy for improving the device performance. [6] Usually, the band bending and built-in electric field can sufficiently manipulate the charges, thereby to improve exciton recombination. [7] MXene, as a new family of 2D layered material consisting of early transition metal carbides and nitrides, becomes a promising class of 2D materials in many applications because of their rich surface functional groups and excellent electrical conductivity. [8] The surface of MXene contains rich terminations, which provide adsorption sites for semiconductor metal oxides. [9] Some studies in polymer solar cells have shown that ZnO is adsorbed onto Ti 3 C 2 T x nanosheet to form charge transfer channels. [10] The regulation effect of Ti 3 C 2 T x on the work function of ZnO was also reported in perovskite light-emitting diodes. [11] However, the modulation of Ti 3 C 2 T x on QLEDs is rarely reported.Herein, we prepared high-quality and uniform monolayer Ti 3 C 2 T x nanosheets via a cryogenic pretreatment-assisted minimally intensive layer delamination (MILD) technique. The efficient B-QLED was obtained by using ZnMgO-Ti 3 C 2 T x hybrid ETL. The monolayer Ti 3 C 2 T x was incorporated into the ZnMgO can effectively suppress the non-radiative recombination of QD caused by metal oxide. Moreover, the addition of Ti 3 C 2 T x tunes the WF of ZnMgO and alleviates the charge accumulation at the QD/ETL interface, which improves the efficiency and operational stability of QLEDs. In virtue of these preponderances, Quantum-dot light-emitting diodes (QLEDs) are proposed as one of the most promising candidates for next-generation displays, but their commercial application is seriously limited due to the poor performance of blue QLEDs (B-QLEDs). Herein, this work uses Ti 3 C 2 T x nanosheets to tune the work function (WF) of ZnMgO and to engineer the quantum dot (QD)/electron transport layer (ETL) interface. The B-QLEDs with ZnMgO-Ti 3 C 2 T x hybrid ETL exhibit a maximum EQE of 15.81% and a remarkable T 50 operation lifetime of 3284 h at 100 cd m −2 . In addition to that, ultraviol...

Color Revolution: Prospects and Challenges of Quantum‐Dot Light‐Emitting Diode Display Technologies

“…Although the over injected electrons could lead to the charge imbalance, there are few studies showing that efficient electron injection into the QDs is a crucial factor for high-performance blue QLEDs. [214][215][216][217] For example, Liao et al reported that in inverted QLEDs, by inserting PEIE at the ITO/ZnO interface and incorporating little PEIE in ZnO, the electron injection barrier at both the ITO/ZnO and ZnO/QDs interfaces was reduced, resulting in an easier electron injection. The optimized blue QLED showed an EQE of 7.85%, which is 1.4 times higher compared to that of the reference device without PEIE.…”

Enhanced Hole Injection in Blue Quantum‐Dot Light‐emitting Diodes Utilizing Dual Hole Injection Layer of PEDOT:PSS/Ti3C2Tx

“…[1][2][3][4][5][6] Recent advancements in quantum-dot emitter materials and device engineering have significantly enhanced the performance of QLEDs. [7][8][9] However, the efficiency and stability of blue QLEDs are much lower than those of red and green counterparts, which renders their practical applications become difficult. Charge injection imbalance caused by low hole injection efficiency greatly restricts the performance of blue QLEDs.…”

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

“…Compared to red and green QLEDs, the wider bandgap of blue QD results in different interfacial charge transfer mechanisms. On the one hand, the vast hole injection barrier hinders hole injection, resulting in charge imbalance in the QD emitting layer, − especially at high current density. As a result, the Auger recombination rate increases, and efficiency roll-off (defined as the efficiency drops significantly) at high current density .…”