Browsing by Subject "Interlayer"

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Open Access
On the triplet distribution and its effect on an improved phosphorescent organic light-emitting diode
(AIP Publishing, 2012-08-28) Liu, S. W.; Divayana, Y.; Abiyasa, A. P.; Tan S.T.; Demir, Hilmi Volkan; Sun, X. W.
We reported phosphorescent organic light-emitting diodes with internal quantum efficiency near 100% with significantly reduced efficiency roll-off. It was found that the use of different hole transporting layer (HTL) affects the exciton distribution in the emission region significantly. Our best device reaches external quantum efficiency (EQE), current, and power efficiency of 22.8% +/- 0.1%, 78.6 +/- 0.2 cd/A, 85 +/- 2 lm/W, respectively, with half current of 158.2 mA/cm(2). This considerably outperforms the control device with N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) (HTL) and 4,4'-N,N'-dicarbazole-biphenyl (host) with maximum EQE, current and power efficiency of 19.1% +/- 0.1%, 65.6 +/- 0.3 cd/A, 67 +/- 2 lm/W, respectively, with half current of only 8.1 mA/cm(2).
Open Access
Ultra-lightweight Chemical Vapor Deposition grown multilayered graphene coatings on paper separator as interlayer in lithium-sulfur batteries
(Elsevier, 2019) Cengiz, E. C.; Salihoğlu, Ömer; Öztürk, O.; Kocabaş, Coşkun; Demir-Çakan, R.
Lithium-Sulfur (Li-S) batteries are known for their high energy density and cost-effectiveness. However, the Li-S chemistry is a challenging topic due to the shuttle effect and the use of highly reactive lithium metal anode. To solve these issues, ultra-lightweight multilayered graphene coated paper separator is proposed as an interlayer. The interlayer is firstly coated on nickel foil by Chemical Vapor Deposition (CVD) method followed by transferring to the paper by fishing process. By employing this unique technique, a very light (~8 mg/cm2 ) graphene coating layer is obtained which does not further imply lowering the entire energy density of the cell. As a whole, the cell with graphene coated paper exhibits 610 mAh/g discharge capacity at C/5 after 100 cycles, while the cell without interlayer exhibits much poorer performance. The improved performance is mostly associated with the interaction between graphene and polysulfide species which is proven by X-Ray Photoelectron Spectroscopy measurement as well as the excellent electronic conductivity of graphene layer which behaves as a secondary current collector resulting the cell resistance decrease.