Highly-efficient organic light-emitting devices based on poly(<i>N</i>,<i>N</i>′-bis-4-butylphenyl-<i>N</i>,<i>N</i>′-bisphenyl)benzidine:octadecylamine-graphene quantum dots

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Organic light-emitting devices (OLEDs) with a poly(<I>N</I>,<I>N</I>′-bis-4-butylphenyl-<I>N</I>,<I>N</I>′-bisphenyl)benzidine (poly-TPD):octadecylamine (ODA)-graphene quantum dots (GQDs) hole transport layer (HTL) were fabricated to enhance their efficiency. Photoluminescence (PL) and PL excitation spectra showed that the optical energy bandgap of the ODA-GQDs was 2.7 eV, and ultraviolet photoelectron spectroscopy spectra demonstrated that the edge of the highest occupied molecular orbital of the ODA-GQDs was 5.3 eV below the Fermi level. While the operating voltage of the OLEDs with a PVK:ODA-GQD (9.77 V, 0.25 wt%) HTL at 10 mA/cm<SUP>2</SUP> was 0.8 V lower than that of the OLEDs with a poly-TPD HTL (10.57 V), their current efficiency was larger by more than 20% than that of the OLEDs with poly-TPD (32.88 cd/A) due to an increase in the number of holes injected from the ITO to the HTL. The number of injected holes was increased due to a reduction of the energy barrier and an increase in the conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Organic light-emitting devices (OLEDs) were fabricated with poly-TPD:ODA-GQDs. </LI> <LI> Oxygen content of the ODA-GQDs was smaller than that of the typical GQDs. </LI> <LI> Operating voltages of the OLEDs with poly-TPD:ODA-GQDs at 10 mA/cm<SUP>2</SUP> was 9.77 V. </LI> <LI> Current efficiency of the OLEDs with the poly-TPD:ODA-GQDs was 39.77 cd/A. </LI> <LI> Enhancement of the efficiency was achieved due to the increased injected holes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>