Blue phosphorescent organic light-emitting devices utilizing cesium–carbonate-doped 2,4,6-tris(2′,4′-difluoro-[1,1′-biphenyl]-4-yl)-1,3,5-triazine

Abstract

Abstract. We report an alternative, high-yielding synthesis for the known compound 2,4,6-tris(2 ,4 -difluoro-[1,1 -biphenyl]-4-yl)-1,3,5-triazine (tris-(dFB)Tz). The energy of the lowest unoccupied molecular orbital (E LUMO ) for tris-(dFB)Tz is estimated to be −3.5 eV from electrochemical measurements. The deep E LUMO of tris-(dFB)Tz affords a material with excellent electron acceptor characteristics for use in n-doped electron transport layers. Tris-(dFB)Tz shows a four order of magnitude increase in the number of carriers on doping with 8 wt. % Cs 2 CO 3 . Enhanced electron injection was also observed on doping with Cs 2 CO 3 , which eliminated the necessity for a separate LiF electron injection layer. Blue phosphorescent organic light-emitting devices (OLEDs) were fabricated using n-doped tris-(dFB)Tz electron transport layers. OLEDs with thick (700-Å) Cs 2 CO 3 -doped tris-(dFB)Tz electron transport layers had lower operating voltages than OLEDS with an undoped electron transport layer of bis(diphenylphosphoryl)dibenzothiophene (PO15), which has previously been used in lowvoltage, high-efficiency OLEDs. The tris-(dFB)Tz results indicate that aromatic substituted triazines may be promising materials for use as electron acceptors in n-doped organic electronic systems. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Highly Efficient n‐Doping via Proton Abstraction of an Acceptor1‐Acceptor2Alternating Copolymer toward Thermoelectric Applications

“…[35][36][37][38][39][40][41] In the context of OLED research, the viability of further alkali carbonates as n-type dopants has been demonstrated, suggesting redox activity of the carbonate anion. [37,[42][43][44][45] Liu et al investigated the thermoelectric performance enhancement of a fullerene derivative doped by thermally evaporated Cs 2 CO 3 , but did not comment further on the underlying mechanism. [46] The authors like to point out the distinct difference between carbonate-doping of small molecule semiconductors such as 1,10-phenanthroline or bathocuproine and semiconducting polymers.…”

New Class of Wide Energy Gap Benzotriimidazole Optical Materials

“…Great effort has been spent for decades to develop new luminescent organic semiconductors for organic light-emitting diodes (OLEDs) [1][2][3][4][5][6][7][8][9][10]. The OLED field requires organic fluorophores with highly efficient emission that can act as hole-transporting electron donors or as electron-transporting electron acceptors [11][12][13][14][15][16][17][18][19][20].…”

Temperature dependence of cesium carbonate-doped electron transporting layers on organic light-emitting diodes

“…In particular, the low power consumption of OLED-displays has attracted strong interest for many portable commercial and military applications [4]. In fact, the OLED display is rapidly moving from fundamental research into industrial product, creating many new challenges like lower operation voltage and power consumption, and operating under extreme environmental conditions [5,6]. Research to lower the OLED operating voltage has led to the development of enhanced electron injection with the integration of alkali metals and alkali metal complexes (such as cesium carbonate, Cs 2 CO 3 ) as a sub-monolayer deposited between the organic electron transporting layer (ETL) and the metal cathode [7,8].…”