Experimental and Theoretical Approaches for Detecting Latent Lateral Leakage Current of Organic Light-Emitting Diodes

High-resolution organic light-emitting diode (OLED) displays often suffer from image quality deterioration due to lateral leakage current (LLC). We performed the detection of LLC using operando electric-field-induced doubly resonant sum-frequency generation (EFI-DR-SFG) measurements under conditions where the electric potential, formed by the LLC to an adjacent pixel, was below the emission threshold voltage for the use of OLEDs. The EFI-DR-SFG outputs of the voltage-applied pixel and its adjacent pixel (nonvoltage-applied pixel) were compared as voltage was applied to the OLEDs. In the case of the OLEDs without LLC generation, changes in the EFI-SFG output according to the applied voltage were confirmed only in the voltage-applied pixel, and the SFG output did not change in the adjacent pixel. However, in the case of OLEDs with LLC, changes in SFG output could be observed in the adjacent pixel depending on the electric potential formed by the LLC. These results can potentially lead toward the detection and precise control of hidden LLC prior to light emission, which could not be detected by the conventional emission method.