•Ag nanoparticles were inserted between OLED substrate and color conversion layer.•Color conversion efficiency was enhanced by Ag nanoparticles because of LSPs.•Ag nanoparticles decreased the thickness of surface color conversion layer.This paper demonstrates localized surface plasmons (LSPs) enhanced color conversion efficiency in organic light-emitting device (OLED) with surface color conversion layer (SCCL). Ag nanoparticles (AgNps) deposited by thermal evaporation between substrate and SCCL were used for localized surface plasmons. The high-density, strong photons-LSPs coupling achieved by AgNps leads to a photoluminescence (PL) enhancement in the SCCL. The electroluminescent (EL) measurements show that SCCL–OLED incorporated with AgNps has a 28% enhancement in color conversion efficiency compared with that of a conventional SCCL–OLED without AgNps which is attributed to strong electromagnetic field caused by LSP resonance of AgNps. Moreover, we verify that SCCL with LSPs of AgNps can effectively decrease the thickness of SCCL in the OLED.

•A very simple printing and transferring process for improving OLEDs performances.•A pyramid-based texture film was introduced to OLEDs and proved efficiency.•The pyramid-based structure was introduced from solar cells.•This method is simple and effective without any side effects.This paper showed a very simple method to increase the light extraction of organic light-emitting diodes (OLEDs) by attaching an inverted pyramid texture film to them. The texture film was fabricated by transferring the pyramid-based textured morphology of mono-crystalline silicon surface using a printing process. Compared to the reference device, our results showed a great improvement in the current efficiency (+37.0%) and external quantum efficiency (+36.6%) at a current density of 100 mA/cm2. Furthermore, the EL spectrum and CIE coordinates of the OLEDs did hardly vary with the introduction of the texture film and variation of viewing angles, and the OLED with the texture film was proved to be a perfect Lambertian emitter, which suggested that the utilization of this method was a promising approach for the development of OLEDs and could be suggestive conduction to EL lightening and backlight.Graphical abstract

We developed high color rendering index (CRI) white organic light emitting diodes (WOLEDs) by the incorporation of yellow or green fluorescence emission located between the monomer and excimer emission of platinum [1,3-difluoro-4,6-di (2-pyridinyl) benzene]chloride (Pt-4). The devices comprising yellow or green fluorescence emission exhibited a maximum CRI of 92 and 94, respectively. Meanwhile, the devices showed excellent chromatic stability and low efficiency roll-off. We attribute the high CRI to the perfect spectrum complement and the relative intensity adjustment between two emission layers (EMLs). The mechanism of triplet excition confinement plays a crucial role in the suppression of chromaticity shifting and efficiency roll-off.Graphical abstractWe developed high color rendering index (CRI) white organic light emitting diodes (WOLEDs) by the incorporation of yellow or green fluorescence emission located between the monomer and excimer emission of platinum [1,3-difluoro-4,6-di (2-pyridinyl)benzene]chloride (Pt-4). The devices comprising yellow or green fluorescence emission exhibited a maximum CRI of 92 and 94, respectively. Meanwhile, the devices showed excellent chromatic stability and low efficiency roll-off.Highlights► We developed high-CRI and chromatic-stable white OLEDs. ► The incorporation of fluorescence with excimer emission results in the high CRI. ► Triplet excition confinement suppresses color shifting and efficiency roll-off. ► The interlayer plays a crucial role in the triplet excition confinement.

Commercially-available single walled carbon nanotubes (SWCNTs) were used to fabricate SWCNT sheets for anodes of organic light-emitting diodes (OLEDs) by spray-coating process without any use of surfactant or acid treatment. A layer of DMSO doped PEDOT:PSS was spray-coated on the SWCNT sheets to not only lessen the surface roughness to an acceptable level, but also improve the conductivity by more than three orders of magnitude. For our SWCNT-based OLEDs of tris-(8-hydroxquinoline) aluminum (Alq3) emission layers, a maximum luminance 4224 cd/m2 and current efficiency 3.12 cd/A were achieved, which is close to the efficiency of ITO-based OLEDs. We further found out that our OLEDs based on the PEDOT:PSS covered SWCNT anodes tripled the contrast ratio of the conventional indium tin oxide (ITO) based OLEDs.Graphical abstractHighlights► Commercially-available SWCNTs were used as anodes to construct OLEDs. ► High quality SWCNT sheets were fabricated easily by spray-coating process. ► PEDOT:PSS layers greatly improved conductivity and roughness of SWCNT anodes. ► High efficiency of our SWCNT OLEDs was achieved, close to that of the ITO OLEDs. ► PEDOT:PSS-covered SWCNT sheets considerably enhanced contrast ratio of OLEDs.

Efficient color-stable fluorescent white organic light-emitting diodes based on a blue fluorescent host 2-(t-butyl)-9,10-di(2-naphthyl)anthracene(TBADN) co-doped with a blue guest p-di(p-N,N-diphenyl-amino-styryl)benzene(DSA-ph) and a red guest 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB) were reported. The luminance mechanism was explored by analyzing the characteristics of devices with different doping concentrations. It was found that DSA-ph showed effective assistant energy transfer ability in the system. When 1.5% DSA-ph and 0.5% DCJTB were doped, the energy of the system could be most effectively utilized, achieving a maximum luminance efficiency of 14.26 cd/A at 40 mA/cm2, with a color rendering index of 80. The Commission International de L’Eclairage coordinates changed slightly from (0.3381, 0.3327) to (0.3336, 0.3203), as the applied current density increased from 20 mA/cm2 to 200 mA/cm2. The high efficiency could be attributed to effective utilization of host energy, as well as the depression of concentration quenching, and the color stability may be ascribed to the efficient energy transfer from host to both guests in direct and indirect ways and efficient exciton confinement.Highlights► The assistant energy transfer mechanism was introduced to analyze the improvement of co-doped fluorescent WOLEDs. ► By analyzing the EL spectra of the devices, the PL and Abs spectra of the material, the assistant energy transfer mechanism was demonstrated to exist. ► The CIE coordinates was very stable, changing slightly from (0.3381, 0.3327) to (0.3336, 0.3203), as the current density increased from 20 mA/cm2 to 200 mA/cm2. ► A high current efficiency of 14.26 cd/A at 40 mA/cm2 was achieved. ► A color rendering index of 80 was achieved.