White-light electroluminescence from soluble oxadiazole-containing phenylene vinylene ether-linkage copolymer

Abstract

We report a promising oxadiazole-containing phenylene vinylene ether-linkage copolymer, which can emit nearly white light from a single-layer light-emitting diode. The emission spectrum is composed of a red component originating from the new excited dimer in addition to the blue-green component from an individual lumophore and excimer. This excited dimer is formed under a strong electric field inside the diode and cannot be produced by photoexcitation, which is different from the excimer or exciplex that is often found both in photoluminescence and electroluminescence, and it is termed the “electromer.”

High‐Efficiency White‐Light‐Emitting Devices from a Single Polymer by Mixing Singlet and Triplet Emission

“…The EL device showed a luminance efficiency of 1.1 cd A -1 with Commission Internationale de L'Eclairage (CIE) coordinates of (0.29, 0.31). Lee et al [10] fabricated a single-component WPLED using an oxadiazole-containing, phenylene-vinylene ether-linkage copolymer, POPPPV3, as emitting species. The PLED made from annealed POPPPV3 had a luminance efficiency of 0.071 cd A -1 , and a maximum luminance of 60 cd m -2 with CIE coordinates of (0.30, 0.37).…”

White-light-emitting diode based on a single-layer polymer

“…[10][11][12][13] In case of PFB, the electromer could be regarded as an excited state of paired sites with opposite charging (hole and electron, respectively) on the excited PFB molecules (PFB + /PFB -)* under electric excitation. We can also consider that one of the paired PFB molecules carries an excessive hole while the other carries an electron.…”

“…[6][7][8][9] Alternatively, WLEDs can be achieved on the basis of electroplex or electromer emissions, where new specimens form in the active layer between different or identical molecules to produce the required spectrum for filling the gaps in the white-light spectrum. [10][11][12][13] Electromer is referred to as a pair of chemically identical molecules charged by electrons and holes, respectively, which are statistically independent of each other. 12 The corresponding device generally produces red-shifted EL spectrum as compared to the intrinsic molecular emission.…”

White‐Light Emission from a Single‐Emitting‐Component Organic Electroluminescent Device

“…Early in 1997, Yang [12] reported a single-emitting-component whitelight-emitting device in which the polyfluorene derivative, poly[9,9-bis(3,6-dioxaheptyl)fluorene-2,7-diyl] (BDOH-PF), was used as the emitter. POPPPVC3 copolymer [13] was also used to fabricate a single-emitting-component WOLED, in which the blue±green light of the white electroluminescence (EL) comes from the individual lumophore and excimer, whereas the red light originates from a new emitting species called an electromer. Recently, another single-emitting-component polymer white EL was obtained with red emission coming from aggregates and molecular blue fluorescence.…”