First-Principles Study of Blue Phosphorene and Graphene Intralayer Heterostructure as Anode Materials for Rechargeable Li-lon Batteries

There is an ideal desire to develop the high-performance anodes materials for Liion batteries(LIBs),which requires not onlyhigh stability and reversibility,but also rapidcharging/discharging rate.In this work,webuiltablue phosphorene-graphene(BlueP-G)intralayer heterostructure by connecting BlueP and graphene monolayers at zigzag edges with covalent bonds.Based on the density functional theory simulation,the electronic structure of the heterostructure,Li adsorption and Li diffusion on heterostructure were systematically investigated.Compared with the pristine BlueP,the existence of graphene layer increases the overall conductivity of BlueP-G intralayer heterostructure.The significantly enhanced adsorption energy indicates the Li deposition on anode surface is energetically favored.The fast diffusion of Li with energy barrier as low as 0.02-0.09 eV indicates the growth of Li dendrite could be suppressed and the stability and reversibility of the battery will be increased.With a combination of increased conductivity of electronic charge,excellent Li adsorption and Li mobility on surface,BlueP-G intralayer heterostructure with zigzag interface is quite promising in the application of anode material for Li-ion batteries.

Highly efficient pure white polymer light-emitting devices based on poly(N-vinylcarbazole) doped with blue and red phosphorescent dyes

Efficient white-polymer-light-emitting devices (WPLEDs) have been fabricated with a single emitting layer containing a hole-transporting host polymer,poly(N-vinylcarbzole),and an electron-transporting auxiliary,1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene,codoped with two phosphorescent dyes:Iridium(III)bis (2-(4,6-difluorophenyl)-pyridinato-N,C2') picolinate (FIrpic) and home-made Ir-G2 for blue and red emission,respectively.With the structure of ITO/PEDOT:PSS 4083(40 nm)/emission layer(80 nm)/Ba(4 nm)/Al(120 nm),the device showed a maximal luminous efficiency (LE) of 13.5 cd A-1(corresponding to an external quantum efficiency (EQE) of 6.8%),and a peak power efficiency (PE) of 6.5 lm W-1 at 6.0 V.Meanwhile,the device exhibited pure white emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.34,0.35) at a current density of 12 mA cm-2,which is very close to the equi-energy white point with CIE coordinates of (0.33,0.33).The device performance can be further optimized when more balanced hole/electron injection is achieved by incorporating a lower conducting type anode buffer layer (PEDOT:PSS) and incorporating poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorenene)-alt-2,7-(9,9-dioctyfluorene)] (PFN) as an electron injection layer at the cathode.The optimized device showed an LE of 24.6 cd A-1 (with an EQE of 14.1%),while the peak power efficiency reached 12.66 lm W-1.Moreover,the WPLEDs showed good electroluminescence (EL) stability over a wide range of operating current density and luminance.