Solution‐Processed Composite Interfacial Layer of MoO_x‐Doped Graphene Oxide for Robust Hole Injection in Organic Light‐Emitting Diode

Abstract

Solution‐processed composite hole injection interfacial layer (HIL) of MoOx‐doped graphene oxide (GO + MoOx) is facilely fabricated. Using GO + MoOx HIL, we demonstrate highly efficient tris(8‐hydroxy‐quinolinato)aluminum‐based organic light‐emitting diodes with maximum luminous efficiency of 8.6 cd A−1, power efficiency of 5.7 lm W−1, and external quantum efficiency of 3.5%, which have been enhanced by 41.0% (75.5%), 39.0% (96.6%), and 40.0% (75.0%), respectively, in comparison with the counterpart using simple HIL of MoOx (GO). Atomic force microscopy and X‐ray/ultraviolet photoelectron spectroscopy measurements show GO + MoOx behaving superior film morphology and extra electronic properties such as enhanced surface work function. Current–voltage characteristics and impedance spectroscopy of hole only cells elucidate that GO + MoOx substantially promotes hole injection and thus accounts for excellent device performance. Our results pave a way for advancing organic electronic devices with solution process as well as boosting GO application.

Improved Efficiency of Perovskite Light-Emitting Diodes Using a Three-Step Spin-Coated CH3NH3PbBr3 Emitter and a PEDOT:PSS/MoO3-Ammonia Composite Hole Transport Layer

“…Several groups have tried to employ the MoO 3 doped HTLs in organic-inorganic PeLEDs and other LEDs in order to obtain better performance of devices [24,25,26]. Kim et al [25] reported the enhanced performance of CH 3 NH 3 PbBr 3 PeLEDs caused by a solution-processed MoO 3 and PEDOT:PSS (PEDOT:MoO 3 ) composite HTL with the MoO 3 concentration in the range of 0.1~0.7 wt.%.…”

“…It is noted that the MoO 3 concentration in the composite is small, and the electron transport material (SPW-111) is not usually used in PeLEDs. Besides, Zheng et al developed a composite hole injection layer (HIL) of MoO x -doped GO in tris(8-hydroxy-quinolinato)aluminum (Alq 3 )-based OLEDs [24], and Meng et al modified the PEDOT:PSS HTL by doping a MoO 3 ammonia solution with largely adjusted volume ratio of (0~0.8):1 in all inorganic CsPbBr 3 PeLEDs [26]. According to these results, the doping of MoO 3 in HTLs is promising to reduce the contact barrier and luminescent quenching at PEDOT:PSS/EML interface.…”

Organic Interface Engineering for Stable Green PHOLEDs through an Ultrathin Interface Tunneling Layer

“…For even higher voltages, > V bi , the capacitance of the OLED decreases rapidly, as holes and electrons recombine, annihilating charges. Primarily, Device B showed lower V bi than those of others, resulting from the improvement of charge injection behaviors ( V bi : 4.61, 4.14, and 5.02 V for Devices A, B, and C, respectively).…”

Improved Charge Injection and Transport of Light-Emitting Diodes Based on Two-Dimensional Materials

“…A maximum luminance of 17939 cd/m 2 and maximum CE of 3.74 cd/A was observed in the OLED with PEDOT:PSS:GO (0.8 wt.%) composite HIL, showing an enhancement of 46.6% and 67.6% compared with the reference OLED, respectively. Zheng studied Alq 3 -based OLEDs using GO:MoO x composite HILs with the ratios of 1:0, 1:6, 1:8, 1:10, 0:1, as shown in Figure 4c [40]. The OLED device with the ratio of 1:8 showed maximum CE of 8.6 cd/A and EQE of 3.5%, which have been enhanced by 41.0% (75.5%) and 40.0% (75.0%) compared with the control device using individual MoO x (GO) HIL, respectively.…”