Red-Emission Oligofluorene Electrophosphorescent Diodes Based on Bis[2-(9,9-dihexyl-9H-fluoren-2-yl)quinolineC3,N]acetylacetonatoiridium(III) and Solvent Treatment for Interface Modification

Abstract

Efficient solution-processed organic light emitting diodes based on oligofluorene doped with bis[2-(9,9-dihexyl-9H-fluoren-2-yl)quinoline-C3,N]- acetylacetonatoiridium(III) [Ir(C6flq)2(acac)] have been demonstrated. The oligofluorene and [Ir(C6flq)2(acac)] show excellent solubility and processibility, with a device performance of 7.83+/-0.52 cd A(-1) and 3.30+/-0.10 lm W(1-) at 2479+/-45 cd m(-2) brightness with Commission International de L'Eclairage coordinates (0.66, 0.33). It was discovered that the efficiency can be further enhanced by exposing the finished organic thin film to a polar solvent or solvent vapor before deposition of the cathode contact. As a result, a peak efficiency of 12.20+/-0.16 cd A(-1) and 6.35+/-0.03 lm W(1-) at 1821+/-238 cd m(-2) brightness is achieved. This efficiency enhancement can be attributed to the presence of interface dipoles between the light-emitting layer and cathode contact.

Modification of Optical Band Gap and Surface Morphology of NiTsPc Thin Films

“…A solvent treatment process has also been utilized for organic light emitting diode applications since the modification of the active layer can assist the charge carrier to transport to its respective electrodes. [17] However, in this Letter, the treatment method is different. The NiTsPc films are modified by immersing them in low solubility solvent to modify their optical band gap and surface morphology.…”

Red-green-blue polymer light-emitting diode pixels printed by optimized laser-induced forward transfer

“…16 When doped with triplet emitters, the EL emission color can be changed from blue to green or red. 17,18 The LIFT deposited devices are referred to as a LIFTed pixels to differentiate them from conventionally fabricated devices.…”

“…17,18 The device characteristics of the pixels and conventional devices are shown in Table I and Fig. 3.…”

Solution processed organic light-emitting diodes with improved cathode interfacial structure

“…On the other hand, the solvent has been found playing a prominent role in the improvement of charge injection [9] . Some of the EIL mentioned here can assist the charge injection because of their electric properties, for example, low work function; others may react with metal or emissive layer to form a n-type layer at the interface, therefore, improve the charge injection by reducing the energy barrier at the interface.…”