The surface plasmonic effect and scattering effect of gold nanorods(AuNRs) on the performance of bulk heterojunction photovoltaic devices based on the blend of polythiophene and fullerene are investigated.AuNRs enhance the excitation since the plasmonic effect increases the electric field,mainly in the area near the interface between the active layer and AuNRs.The results show that the incident photo-to-electron conversion efficiency(IPCE) obviously increases for the device with a layer of gold nanorods,resulting from the plasmonic effect of AuNRs in the range of 500-670 nm and the scattering effect in the range of 370-410 nm.The power conversion efficiency(PCE) is increased by 7.6% due to the near field effect of the localized surface plasmons(LSP) of AuNRs and the scattering effect.The short circuit current density is also increased by 9.1% owing to the introduction of AuNRs.However,AuNRs can cause a little deterioration in open circuit voltage.
High-brightness and color-stable two-wavelength hybrid white organic light emitting diodes (HWOLEDs) with the configuration of indium tin oxide (ITO)/ N, N, N, N-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD): tetrafluoro-tetracyanoqino dimethane (F4-TCNQ)/N,N-di(naphthalene-1-yl)-N,N-diphenyl-benzidine (NPB)/ 4,4-N,N-dicarbazolebiphenyl (CBP): iridium (III) diazine complexes (MPPZ) 2 Ir(acac)/NPB/2-methyl-9,10-di(2-naphthyl)anthracene (MADN): p-bis(p-N,N-di-phenyl-aminostyryl)benzene (DSA-ph)/bis(10-hydroxybenzo[h] quino-linato)beryllium complex (Bebq2)/LiF/Al have been fabricated and characterized. The optimal brightness of the device is 69932 cd/m2 at a voltage of 13 V, and the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates are almost constant during a large voltage change of 6-12 V. Furthermore, a current efficiency of 15.3 cd/A at an illumination-relevant brightness of 1000 cd/m2 is obtained, which rolls off slightly to 13.0 cd/A at an ultra high brightness of 50000 cd/m2. We attribute this great performance to wisely selecting an appropriate spacer together with effectively utilizing the combinations of exciton-harvested orange-phosphorescence/blue-fluorescence in the device. Undoubtedly, this is one of the most exciting results in two-wavelength HWOLEDs up to now.
In this paper,the pentacene-based organic field-effect transistors(OFETs)with poly(methyl methacrylate)(PMMA)as gate dielectrics were fabricated,and the effects of gate dielectric thickness and semiconductor thickness on the device performance were investigated.The optimal PMMA thickness is in the range of 350–400 nm to sustain a considerable current density and stable performance.The device performance depends on the thicknesses of the active layer non-monotonically,which can be explained by the morphology of the pentacene film and the position of the conducting channel in the active layer.The device with a pentacene thickness of 50 nm shows the best performance,which has a maximum hole mobility of 1.12 cm2/V·s.In addition,the introduction of a thin layer of tris-(8-hydroxyquinolinato)aluminum(Alq3)to the OFETs as a light-emitting material greatly decreases the device performance.
We report on white organic light-emitting diodes(WOLEDs) based on polyvinylcarbazole(PVK) doped with 1,1-bis((di-4-tolylamino)phenyl)cyclohexane(TAPC) and perylene,and investigate the luminescence mechanism of the devices.The chromaticity of light emission can be tuned by adjusting the concentration of the dopants.White light with the Commission Internationale de L'Eclairage(CIE) coordinates of(0.33,0.34) is achieved by mixing the yellow electromer emission of TAPC and the blue monomer emission of perylene from the device ITO/PVK:TAPC:perylene(100:9:1 in wt.)(100 nm)/tris-(8-hydroxyquinoline aluminum(Alq 3)(10 nm)/Al.The device exhibits a maximal luminance of 3727 cd/m2 and a current efficiency of 2cd/A.
We investigate the effect of a metallic electrode on the ability for poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4phenylene vinylene](MEH-PPV) film to undergo amplified spontaneous emission(ASE).The threshold of the device with Ag cladding is about 10 times greater than that of a metal-free device,but metal such as Al completely shuts off ASE.The ASE recurs when a thin spacer layer,such as a few nanometers of SiO 2,is introduced between the MEH-PPV film and the Al cladding.Compared with the Cu or Al electrode,the Ag cladding is most suited to serve as an electrode with its low optical loss due to its high work-function and reflectivity.
