Effects of Localized Heating at Heterointerfaces on the Reliability of Organic Light-Emitting Diodes

Abstract

Continuous-wave and pulsed-current stressing was conducted to evaluate the reliability of green phosphorescent organic light-emitting diodes (OLEDs). Through modifications of the ITO anode by different pretreatments and the hole transport layer (HTL) by incorporating inorganic component or dopants, we proved that the energy level misalignment at the ITO/HTL interface leads to localized Joule heating, accelerating material deterioration, and luminescence decay. Stressing with short current pulses was employed to suppress the heating effect. For OLEDs with a large interfacial barrier of 1.2 eV, the effective half life was increased by 70% under pulsed operation, whereas in OLEDs with an interfacial barrier of 0.5 eV, only 14% improvement was obtained, indicating a minor heating role.

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

“…OLEDs, in which EML is an organic material such as Tris-(8-hydro-xyquinoline)aluminum (Alq 3 ), have attracted intensive interest because of their excellent properties such as low cost, high brightness and flexibility [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The organic material employed in OLEDs is an organic semiconductor, which contains small organic molecules and organic polymers.…”

“…Although inorganic LEDs based on III-V semiconductors such as GaN and InGaN have made semiconductor solid state lighting popular, accompanied with the significant saving of energy, the high-temperature, expensive vacuum-based manufacturing process employed to fabricate these semiconductors restricts their widespread application. The substitutes of inorganic LEDs contain organic light emitting diodes (OLEDs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14], quantum dot light emitting diodes (QLEDs) [15][16][17] and perovskite light emitting diodes (PeLEDs) [18][19][20][21][22][23][24][25], which take advantage of the high photoluminescence quantum efficiency (PLQE), solution processability, good purity and tunability of color. For these new types of LEDs, high-efficiency and stable devices are still the objectives of research works.…”

In Situ Visualization and Quantification of Electrical Self‐Heating in Conjugated Polymer Diodes Using Raman Spectroscopy

“…[47][48][49][50] There have been many reports that apply electrical techniques to study self-heating in organic devices based on small molecules. [46][47][48][49][50][51][52][53][54] Particular focus has been placed on studying Joule heating in organic light emitting diodes (OLED) due to the characteristically high operating current densities required for device operation.…”