TY - JOUR
T1 - A wide-energy-gap naphthalene-based liquid organic semiconductor host for liquid deep-blue organic light-emitting diodes
AU - Kobayashi, Naofumi
AU - Kuwae, Hiroyuki
AU - Oshima, Juro
AU - Ishimatsu, Ryoichi
AU - Tashiro, Shuya
AU - Imato, Toshihiko
AU - Adachi, Chihaya
AU - Shoji, Shuichi
AU - Mizuno, Jun
N1 - Funding Information:
The authors thank Yoshiyuki Nakajima (Riken Keiki, Co. Ltd.) for the photoelectron microscopy in air evaluation (AC-3). The authors thank Shunsuke Sawai (Waseda University) for the mass observation. This work was sponsored by the Japan Ministry of Education, Culture, Sports Science & Technology (MEXT) and Grant-in-Aid for Scientific Basic Research (A) No. 16H02349 . The authors thank for the MEXT Nanotechnology Platform Support Project of Waseda University. H.K. was supported by the Early Bird Program of Waseda University, and Leading Graduate Program in Science and Engineering of Waseda University from MEXT, Japan.
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/8
Y1 - 2018/8
N2 - We developed a novel naphthalene derivative to function as a wide-energy-gap liquid organic semiconductor (LOS) host material for the limited range of liquid deep-blue light-emitting materials that have been developed to date. The naphthalene derivative 1-naphthaleneacetic acid 2-ethylhexyl ester (NLQ), which shows a low viscosity of 20 mPa·s at 25 °C, was synthesized as a LOS by introducing an ethylhexyl group into naphthalene. We doped 9,10-diphenylanthracene (DPA) into NLQ as a guest deep-blue dye. The highest occupied molecular orbital (HOMO) energy level of NLQ was estimated to be − 6.40 eV from photoelectron spectroscopy measurements in air. The energy gap of NLQ was estimated to be 4.08 eV from its absorption spectrum, indicating that NLQ has the widest energy gap of any such host material to date. The lowest unoccupied molecular orbital energy level of NLQ was calculated to be − 2.31 eV. Deep-blue electroluminescence emission in a liquid state was obtained by doping DPA into NLQ. Light emission could be achieved by a combination of Förster resonance energy transfer and direct recombination of trapped holes and electrons because the energy gap of DPA is straddled by the wider energy gap of NLQ.
AB - We developed a novel naphthalene derivative to function as a wide-energy-gap liquid organic semiconductor (LOS) host material for the limited range of liquid deep-blue light-emitting materials that have been developed to date. The naphthalene derivative 1-naphthaleneacetic acid 2-ethylhexyl ester (NLQ), which shows a low viscosity of 20 mPa·s at 25 °C, was synthesized as a LOS by introducing an ethylhexyl group into naphthalene. We doped 9,10-diphenylanthracene (DPA) into NLQ as a guest deep-blue dye. The highest occupied molecular orbital (HOMO) energy level of NLQ was estimated to be − 6.40 eV from photoelectron spectroscopy measurements in air. The energy gap of NLQ was estimated to be 4.08 eV from its absorption spectrum, indicating that NLQ has the widest energy gap of any such host material to date. The lowest unoccupied molecular orbital energy level of NLQ was calculated to be − 2.31 eV. Deep-blue electroluminescence emission in a liquid state was obtained by doping DPA into NLQ. Light emission could be achieved by a combination of Förster resonance energy transfer and direct recombination of trapped holes and electrons because the energy gap of DPA is straddled by the wider energy gap of NLQ.
KW - Liquid organic light-emitting diode
KW - Liquid organic semiconductor
KW - Naphthalene-derivative
KW - Wide-energy-gap
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U2 - 10.1016/j.jlumin.2018.03.072
DO - 10.1016/j.jlumin.2018.03.072
M3 - Article
AN - SCOPUS:85044994557
SN - 0022-2313
VL - 200
SP - 19
EP - 23
JO - Journal of Luminescence
JF - Journal of Luminescence
ER -