Fast cell level characterization and reliability evaluation for advanced flexible mobile display

For an advanced flexible mobile display, the elucidation of the charge transfer mechanism of an emissive layer (EL) in an organic light-emitting diode (OLED) is crucial to ensure performance and reliability. To determine the long-term lifetime characteristics, two different ELs were exposed to an accelerated stress test on the cell level and then characterized by luminance-current-voltage (L-I-V), capacitance-voltage (C-V), and impedance measurements. In addition, LDI-TOF analysis was employed for the physical characterization. With a specific test structure, we were able to accelerate the EL degradation, providing fast turnaround results compared to the conventional aging test on the module level. Finally, the optimization of the EL structure is discussed from the reliability perspective.

I. Introduction

Due to the continuously increasing requirements of various display applications, the development of OLEDs (organic light-emitting diodes) has been intensively carried out over the last two decades. The use of OLED technology in high-luminance organic materials and device structures has now attained maturity with high brightness and luminous efficiency with various advantages such as vivid resolution, low power consumption, and flexible possibilities. [1]–[3]