Functionalized terfluorene for solution-processed high efficiency blue fluorescence OLED and electrophosphorescent devices Chung-Feng Wang a , Wen-Yi Hung b,⇑ , Ming-Hung Cheng b , Jih-Shang Hwang b , Man-kit Leung a,c,⇑ , Ken-Tsung Wong c,d,⇑ a Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617, Taiwan b Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan c Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan d Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan article info Article history: Received 16 March 2013 Received in revised form 13 April 2013 Accepted 20 April 2013 Available online 9 May 2013 Keywords: Solution-processed OLED Nondoped blue OLED Host material White OLED abstract A new multifunctional blue-emitting terfluorene derivative (TFDPA) featured with tri- phenylamine groups for hole-transportation and long alkyl chains for solution processabil- ity on the conjugation inert bridge centers was reported. TFDPA can give homogeneous thin film by solution process and exhibits high hole mobility (l h  10 3 cm 2 V 1 s 1 ) and suitable HOMO for hole injection. Particularly, TFDPA performs efficient deep-blue emis- sion with high quantum yield (100% in solution, 43% in thin film) and suitable triplet energy (E T = 2.28 eV), making solution-processed OLED devices of using TFDPA as blue emitter and as host for iridium-containing phosphorescent dopants feasible. The solu- tion-processed nondoped blue OLED device gives saturated deep-blue electroluminescence [CIE = (0.17, 0.07)] with EQE of 2.7%. TFDPA-hosted electrophosphorescent devices per- formed with EQE of 6.5% for yellow [(Bt) 2 Ir(acac)], 9.3% of orange [Ir(2–phq) 3 ], and 6.9% of red [(Mpq) 2 Ir(acac)], respectively. In addition, with careful control on the doping con- centration of [(Bt) 2 Ir(acac)], a solution-processed fluorescence–phosphorescence hybrided two-color-based WOLED with EQE of 3.6% and CIE coordinate of (0.38, 0.33) was success- fully achieved. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Organic light-emitting diodes (OLEDs) have been recognized as a promising alternative display and lighting technology because of their unique advantages such as pa- per-like thickness, faster response, high contrast, power saving, and potentially can be used for flexible appliances [1]. Currently, the commercial small molecule-based OLED displays were fabricated by high-cost thermal deposition technology under high vacuum condition. However, ther- mal deposition has been challenged with some critical is- sues including the low-effective use of expensive materials, and the cost of high-vacuum chambers and fine metal mask, which strictly limit the size of device substrate and the resolution of defined emission pixels. For improving the competitiveness of OLED technology with other coun- terparts, new cost-effective fabrication processes will be highly demanded. In this regard, many efforts for resolving the long-standing challenges of solution-processed OLEDs have shown significantly improved promise [2–5]. Regard- less of the OLED applications either for full-color display or lighting, the device require red, green, and blue emissions with relatively equal stability, efficiency, and color purity. 1566-1199/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.orgel.2013.04.047 ⇑ Corresponding authors. Tel.: +886 02 24622192; fax: +886 02 24634360 (W.-Y. Hung). E-mail addresses: wenhung@mail.ntou.edu.tw (W.-Y. Hung), mkleung@ntu.edu.tw (M.-k. Leung), kenwong@ntu.edu.tw (K.-T. Wong). Organic Electronics 14 (2013) 1958–1965 Contents lists available at SciVerse ScienceDirect Organic Electronics journal homepage: www.elsevier.com/locate/orgel