Operating stability of light-emitting polymer diodes based on poly(p-phenylene vinylene)

Abstract

We have developed modified poly(p-phenylene vinylene) (PPV) to improve its performance in organic electroluminescent devices. Encapsulated single-layer devices with this PPV on indium–tin oxide and a calcium cathode have been operated in air for >7000 h at 20 °C and >1100 h at 80 °C without noticeable degradation. Devices fabricated with this PPV, a conducting polymer layer as anode, and a sputtered low work-function alloy as cathode have efficiencies of over 2 lm/W, brightnesses of >600 Cd/m2 at 4 V, and lifetimes of >1400 h driven at ∼100 Cd/m2 initial brightness.

Correlation between the Indium Tin Oxide morphology and the performances of polymer light-emitting diodes

“…We mentioned above that a similar roughness was found between 10 min-treated ITO and 50 nm PEDOT-PSS covered ITO. Moreover, PEDOT-PSS interlayer increases hole injection [15] and [16] by lowering the hole injection barrier. In addition, the PEDOT-PSS interlayer acts as a buffer layer between BDMO-PPV and ITO and avoids any chemical reaction between BDMO-PPV and ITO, which might possibly harm the correct operation of devices.…”

“…Many surface treatments of the ITO have been employed to improve the device performance, including aqua regia treatment [3], oxygen plasma treatment [4], [5], [6] and [7], atmospheric plasma treatment [8], ultra-violet ozone treatment [9], carbon tetrafluoride/oxygen treatment [10] and various coating treatments such as for example self-assembled monolayers [11] and [12]. Alternatively, by inserting an additional thin layer, such as copper-phtalocyanine [13], polyaniline [14], poly(3,4-ethylene dioxythiophene) doped with polystyrene sulfonate (PEDOT-PSS) [15] and [16], inorganic or organic insulators [17] and [18], emission intensity and device stability can be improved by lowering the driving voltage. The effects of such a buffer layer include the reduction of hole-injection energy barrier and the removal of contaminants from the ITO surface.…”

Controlling the optical properties of a conjugated co-polymer through variation of backbone isomerism and the introduction of carbon nanotubes

“…Two of the major issues are control of emission colour and improvement in emission efficiency. By incorporating appropriate substituents, PPV-derivatives can emit light in the green [3] to red [4] range. However, due to the long conjugation length, it is not normally possible to achieve blue luminescence from this type of material.…”

Controlling the Electronic Interface Properties in Polymer–Fullerene Bulk Heterojunction Solar Cells

“…For polymer solar cells, PEDOT:PSS is the reference anode interface material that is commonly used in solution processed devices [38][39][40][41]. Other solution processed organic materials used as (part of the) cathode are for example poly(ethylene oxide) (PEO) [44], water-soluble polyfluorene (WPF-6-oxy-F) [45] or polyoxyethylene tridecyl ether (PTE) [46].…”