Effect of Joule heating on transient current and electroluminescence in p-i-n organic light-emitting diodes under pulsed voltage operation

• Transient current and EL responses of p-i-n OLEDs based on different substrates driven by 5 µs voltage pulse were studied.
• Temperature rises (ΔT) in 5 µs device operation were calculated by numerical simulations.
• ΔT was estimated to be higher than 100 K at high current density region (>400 A/cm2) from the simulations.

The transient current and electroluminescent characteristics of p-i-n organic light-emitting diodes driven using short voltage pulses with various amplitudes and pulse widths were investigated to understand high current behavior (>10 A/cm2). Even under short voltage pulse operation, Joule heating was found to strongly affect the transient characteristics and lead to temperature rises estimated to be over 100 K in the high current density region (>400 A/cm2). This results in a large increase in both current density and EL intensity within the pulse width. In addition, the Joule heating was found to have an effect on the external quantum efficiency. However its contribution was found to be limited compared with the other quenching mechanism, singlet-polaron quenching.

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