title: Highly Efficient White Organic Light-Emitting Diodes with Ultrathin Emissive Layers and a Spacer-Free Structure.
abstract: Ultrathin emissive layers (UEMLs) of phosphorescent materials with a layer thickness of less than 0.3 nm were introduced for high-efficiency organic light-emitting diodes (OLEDs). All the UEMLs for white OLEDs can be prepared without the use of interlayers or spacers. Compared with devices fabricated with interlayers inserted in-between the UEMLs, our spacer-free structure not only significantly improves device efficiency, but also simplifies the fabrication process, thus it has a great potential in lowering the cost of OLED panels. In addition, its spacer-free structure decreases the number of interfaces which often introduce unnecessary energy barriers in these devices. In the present work, UEMLs of red, green and blue-emitting phosphorescent materials and yellow and blue phosphorescent emitters are utilized for the demonstration of spacer-free white OLEDs. Upon optimization of the device structure, we demonstrated spacer-free and simple-structured white-emitting OLEDs with a good device performance. The current and power efficiencies of our white-emitting devices are as high as 56.0 cd/A and 55.5 lm/W, respectively. These efficiencies are the highest ever reported for OLEDs fabricated with the UEML approach.
authors.affiliation: Institute of Functional Nano &Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials &Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, PR China.
authors.forename: Shengfan
authors.initials: S
authors.lastname: Wu
authors.affiliation: Institute of Functional Nano &Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials &Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, PR China.
authors.forename: Sihua
authors.initials: S
authors.lastname: Li
authors.affiliation: Institute of Functional Nano &Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials &Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, PR China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Institute of Functional Nano &Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials &Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, PR China.
authors.forename: Chenchao
authors.initials: C
authors.lastname: Huang
authors.affiliation: Institute of Functional Nano &Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials &Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, PR China.
authors.forename: Man-Keung
authors.initials: MK
authors.lastname: Fung