A wet and dry processable phosphorescent green dye based organic light-emitting diodes Jwo-Huei Jou a, * , Sun-Zen Chen b , Chih-Chia An a , Shiang-Hau Peng a , Tzu-Yu Ting a , Jing-Jong Shyue c, * , Chih-Lung Chin d, * , Chin-Ti Chen e , Ching-Wu Wang f a Department of Materials Science and Engineering, National Tsing Hua University, Hsin-Chu, Taiwan 30013, People's Republic of China b Center for Nanotechology, Materials Science, and Microsystems, National Tsing Hua University, Hsin-Chu, Taiwan 30013, People's Republic of China c Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan 11529, People's Republic of China d Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsin-Chu, Taiwan 30013, People's Republic of China e Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, People's Republic of China f Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Chia-Yi, Taiwan 62102, People's Republic of China article info Article history: Received 3 June 2014 Received in revised form 19 August 2014 Accepted 1 September 2014 Available online 8 September 2014 Keywords: Organic light emitting diode High efficiency Green emitter Iridium Wet process Dry process abstract Electroluminescence-efficiency green emitter with both wet- and dry-process feasibility is highly desirable to realize cost-effective large roll-to-roll manufacturing and high performance products. We demonstrate here a wet- and dry-process feasible green bis[5-methyl-8-trifluoromethyl-5H-ben- zo(c)(1,5)naphthyridin-6-one]iridium(picolinate) containing organic light-emitting diode device with an efficacy roll-up character between 100 and 1000 cd/m 2 . The newly synthesized iridium complex exhibits a relatively short excited-state lifetime (0.39 ms) and a high quantum yield of 74%, both which warrant this complex to be a highly electroluminescence active candidate. The wet processed device using a 3,5- di(9H-carbazol-9-yl) tetraphenylsilane host, for example, shows a 52 lm/W with an 18% external quantum efficiency (EQE) at 100 cd/m 2 , which increases to 61 lm/W with a 23% EQE at 1000 cd/m 2 . For the dry-processed device using a 4,4-bis(carbazol-9-yl)biphenyl host, it is 59 lm/W with a 25% EQE at 1000 cd/m 2 . © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Organic light-emitting diode (OLED) possesses high potential in high quality flat panel display and solid-state lighting applications [1e3]. Although numerous passive matrix and a few active matrix OLED devices have already in the market and their efficiency is sound, further improving the device efficiency is still very crucial for prolonging the device lifetime [4]. Especially, high efficiency green emission is always required for OLED to be commercially acceptable for illumination. Having an electroluminescence (EL) efficient green emitter, one major component of the 3- or more-band composing white light sources, is highly critical to achieve high efficacy white light since luminous sensitivity of human eyes is the highest with green light and peaking at 555 nm, while becomes decreasingly sensitive drastically as approaching the deep-red or deep-blue region [5]. Having a high efficiency green emission would consequently be able to generate a high efficiency white light. It would be more ideal if any EL-effective green emitters possess both wet- and dry- process feasibility in order to realize, respectively, cost-effective large area size roll-to-roll manufacturing and high performance products. Over the past years, phosphorescent materials have drawn increasing attention because of their ability to fully utilize both singlet and triplet excitons, achieving nearly 100% internal quan- tum efficiency [6e9], and based on which many record breaking efficient OLEDs have hence been fabricated [10e19]. For long wavelength emission devices, for examples, Chi's group reported an Osmium based red device with a 26 lm/W at 1000 cd/m 2 [10]. Jou's group reported an iridium based orange-red device with a 32 lm/W [11]. For green devices, Kido's group reported a 107 lm/W by using a dry-processed iridium based green emitter [12], Jou's group re- ported a 69 lm/W by using a different but wet-process feasible iridium based green emitter [13]. Helander's group reported a 79 lm/W by using chlorinated indium tin oxide electrodes, and efficacy increase to 155 lm/W by using out-coupling [15]. For blue devices, Kido's group reported a 46 lm/W by using an iridium based * Corresponding authors. E-mail addresses: jjou@mx.nthu.edu.tw (J.-H. Jou), shyue@gate.sinica.edu.tw (J.-J. Shyue), clchin@itri.org.tw (C.-L. Chin). Contents lists available at ScienceDirect Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig http://dx.doi.org/10.1016/j.dyepig.2014.09.001 0143-7208/© 2014 Elsevier Ltd. All rights reserved. Dyes and Pigments 113 (2015) 341e350