Efficient quantum dot light emitting devices with ethanol treated PEDOT: PSS hole injection layer

• The ethanol treated PEDOT:PSS is used in QD-LEDs.
• The overall performance of PEDOT:PSS is enhanced with ethanol treated PEDOT:PSS as the HIL.
• AFM measurements indicate the conductivity of ethanol treated PEDOT:PSS films is improved.

The conductivity of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) film is improved by simply mixing PEDOT:PSS solution with ethanol for the film deposition, and the performance of quantum-dot light-emitting diodes (QD-LEDs) is significantly enhanced with ethanol treated (ET- treated) PEDOT:PSS as the hole injection layer (HIL). Comparing with the pristine PEDOT:PSS based device, the current density of device with ET-treated PEDOT:PSS as the HIL is increased by 18%, from 50 to 59 mA/cm2, at operating voltage of 5 V, and the maximum current efficiency is enhanced by 12.5%, from 10.4 to 11.7 cd/A, which is due to the improved conductivity of ET-treated PEDOT:PSS film. With atomic force microscopy (AFM) measurements, we demonstrate that the improvement of the conductivity of PEDOT:PSS film is due to the decreased PSSH amount after solvent treatment, reducing the thickness of PSSH insulating shell, leading to an efficient charge transport across the PEDOT chains.

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