title: Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission.
abstract: Recent developments in the field of π-conjugated polymers have led to considerable improvements in the performance of solution-processed organic light-emitting devices (OLEDs). However, further improving efficiency is still required to compete with other traditional light sources. Here we demonstrate efficient solution-processed multilayer OLEDs using small molecules. On the basis of estimates from a solvent resistance test of small host molecules, we demonstrate that covalent dimerization or trimerization instead of polymerization can afford conventional small host molecules sufficient resistance to alcohols used for processing upper layers. This allows us to construct multilayer OLEDs through subsequent solution-processing steps, achieving record-high power efficiencies of 36, 52 and 34 lm W(-1) at 100 cd m(-2) for solution-processed blue, green and white OLEDs, respectively, with stable electroluminescence spectra under varying current density. We also show that the composition at the resulting interface of solution-processed layers is a critical factor in determining device performance.
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Aizawa
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Pu
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Michitake
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Chiba
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Ideta
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Toyota
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Igarashi
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suzuri
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Hisahiro
authors.initials: H
authors.lastname: Sasabe
authors.affiliation: Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Kido