layer at the anode side of the organic layer stack (in order to create a weak micro cavity together with the reflective cathode). While for blue emitting OLED no efficiency improvement was obtained, this approach almost doubled the luminous efficiency of red emitting OLED, reaching a luminous efficiency of 60 lm/W and an EQE of 21% at 200 cd/m2. For a white emitting OLED consisting of monochrome pixels, this corresponds to an efficiency improvement of more than 30%, so that an overall efficiency of about 40 lm/W can be obtained.
According to Boesing, the next step will be the qualification of organic n-type doping by means of OVPD: Since organic p-type doping by means of OVPD has already been demonstrated successfully, organic n-type doping is the last missing building block for a complete p-i-n diode, which would then also enable vertically stacked multi unit OLED.
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