Organic light-emitting diodes dopants

C.H. Chen and C.W. Tang, Efficient green organic light-emitting diodes with stericaly hindered coumarin dopants, Appl. Phys. Lett., 79 3711-3713 (2001). 

Y. Hamada, H. Kanno, T. Tsujioka, H. Takahashi, and T. Usuki, Red organic light-emitting diodes using an emitting assist dopant, Appl. Phys. Lett., 75 1682-1684 (1999). 

Tetraphenylsilane carbazole derivatives, (IV), were prepared by Chen et al. (4) and used as host material for dopants in organic light-emitting diodes. 

One of the most common uses for peri-substituted pentacene is as a red emitter in organic light-emitting diodes (OLEDs). Diphenylpentacene, for example, has a fluorescence quantum yield of 30% as a 0.55% dopant in Alq3, yielding OLED devices with efficiencies near the theoretical maximum [34]. Variation of the aryl substituents improves solubility and processing and can increase fluorescence quantum yield (for example, pentacene 25 has a composite fluorescence quantum yield of 32%) [35]. There is one report of the use of diaryl pentacenes in FET devices, but the performance was generally poor (hole mobility for vapor-deposited 23 was of the order of 10-8 cm2 V-1 s-1) [30]. 

Niu J, Li W, Wei H, Li M, Su W, Xin Q, Zhang Z and Hu Z, "White organic light-emitting diodes based on bis(2-methyl-8-quinolinolato) (para-phenylphenolato)aluminium(III) doped with tiny red dopant" J. Phys. D Appl. Phys. 38 2005 1136,... 

J.-S. Kim, H. Kajii, and Y. Ohmori, Characteristics of optical response in red organic light-emitting diodes using two dopant system for application to the optical link devices. Thin Solid FUms, 499(1-2), 343-348 (2006). 

W. H. Flora, H. K. Hall, and N. R. Armstrong. Gnest emission processes in doped organic light-emitting diodes Use of phthalocyanine and naphthal-ocyanine near-IR dopants. J. Phys. Chem. B, 107(5) 1142-1150, February 2003. 

Flora WH, Hall HK, Armstrong NR (2002) Guest emission processes in doped organic light-emitting diodes use of phthalocyanine and naphthalocyanine near-IR dopants. J Phys Chem B 107 1142-1150... 

Hamada, Y., Kanno, H., Tsujioka, T., Takahashi, H., Usuki, T., (1999), Red Organic Light-emitting Diodes Using an Emitting Assist Dopant. Appl Phys, Lett. Vol.75, 1682-1684. 

An important breakthrough came with the discovery that with the addition of phosphorescent dopant emitters such as Ft, Ir, Os, etc., the energy could be transferred from the triplet states to the dopant molecules which could decay radiatively. As a result, the internal quantum efficiency (the number of photons generated inside the device per electron-hole pair injected) of these phosphorescent organic light-emitting diodes (PHO-LEDs) (PHOLED is a trademark of the Universal Display Corporation, Ewing, New Jersey) can approach a quantum efficiency 100% at a luminescence of 100 cd/sr. 

---