Capacitance measurements of the polymer light-emitting diodes (PLEDs) with conjugated polyelectrolyte (CPE) electron transporting layers (ETLs) provide important information of device physics for understanding the function of CPEs as ETLs, together with current density-voltage-luminescence measurements. We investigated the counteriondependent capacitance behaviors that present a highly negative or positive capacitance at the low frequency, and suggested different carrier injection mechanisms.

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... pacitance model study reveals that the electron injection mechanism can be described either by the dipole alignment scheme or by electronic charge carrier accumulation at the cathode/ETL/emission layer interfaces.