Efficient and extremely long-lived organic light-emitting diodes based on dinaphthylperylene

Jarikov, Viktor V.; Kondakov, Denis Y.; Brown, Christopher T.

doi:10.1063/1.2809437

Cited by 38 publications

(26 citation statements)

References 33 publications

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“…67,68 Detailed mechanistic studies have shown twisted or freely rotating bonds to disassociate under irradiation and operation. 67,69,70 Lifetimes are improved by a factor of 4-200 in OLED devices that incorporate stiff molecules that strongly aggregate, 71,72 even when the chemical degradation mechanism does not involve oxygen. Generally, OLED lifetimes have improved enough to enter the commercial market, and a review of some of the latest OLED materials shows a trend of more planar, stiffer molecules.…”

Section: Photochemical Reactions In the Absence Of Oxygen And Watermentioning

confidence: 99%

Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

et al. 2015

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For long-term performance chemically robust materials are desired for organic solar cells (OSCs). Illuminating neat films of OSC materials in air and tracking the rate of absorption loss, or photobleaching, can quickly screen a material's photo-chemical stability. In this report, we photobleach neat films of OSC materials including polymers, solution-processed oligomers, solution-processed small molecules, and vacuum-deposited small molecules. Across the materials we test, we observe photobleaching rates that span seven orders of magnitude. Furthermore, we find that the film morphology of any particular material impacts the observed photobleaching rate, and that amorphous films photobleach faster than crystalline ones. In an extreme case, films of amorphous rubrene photobleach at a rate 2500 times faster than polycrystalline films. When we compare density to photobleaching rate, we find that stability increases with density. We also investigate the relationship between backbone planarity and chemical reactivity. The polymer PBDTTPD is more photostable than its more twisted and less ordered furan derivitative, PBDFTPD. Finally, we relate our work to what is known about the chemical stability of structural polymers, organic pigments, and organic light emitting diode materials. For the highest chemical stability, planar materials that form dense, crystalline film morphologies should be designed for OSCs.

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Section: Photochemical Reactions In the Absence Of Oxygen And Watermentioning

confidence: 99%

Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

et al. 2015

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“…A much stronger electric field is required to inject holes into NPB from ITO|CF x |CuPc than from ITO|CF x [10], as illustrated by comparing the drive voltages of otherwise identical device pairs (A,B), (C,E), and (D,F). A much smaller electric field is required to inject and transport electrons through BH|Bphen than through Alq [11], as illustrated by comparing the drive voltages of otherwise identical device pairs (C,D) and (E,F). For devices with the high-field ETL (D,F), increasing the field strength in the HTL occasions more than a doubling of the EQE.…”

Section: Resultsmentioning

confidence: 99%

47.2: Luminescence Quenching in Blue Fluorescent OLEDs

Young

Lenhard

Kondakov

et al. 2008

Symp Digest of Tech Papers

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The radical ion of the familiar hole‐transport material NPB (i.e., NPB⋅+) absorbs strongly in the blue region of the spectrum. Therefore, it can quench blue luminescence by Förster energy transfer. A high concentration of NPB⋅+ at the interface between an NPB hole‐transport layer (HTL) and a blue light‐emitting layer (LEL) severely limits the luminescence efficiency of the emitting blue dopant. The efficiency can be improved dramatically by modifying either (a) the anode contact with a thin layer of CuPc, thereby increasing the field strength in the HTL, or (b) the cathode contact with a thin layer of Bphen, thereby reducing the field strength in the LEL. Both strategies reduce the difference in electric field strength across the interface, reduce the interfacial concentration of NPB⋅+, and suppress the quenching. Experimental evidence is provided by a spectrum of electrochemically generated NPB⋅+, simultaneous photo‐ and electroluminescence measurements on model OLEDs, and electrical characterization of the devices.

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“…Finally this poor interaction induced the dark spots and limited the device lifetime. [86][87][88][89][90][91] A bend test of a multilayer barrier that encapsulated a fl exible OLED display has been carried out by Chwang et al 92 The display was bent under a tensile stress 1000 times around a cylinder of one inch diameter at a rate of approximately 12 bends/min. They reported that after 100 bends the display illustrated no damage.…”

Section: Failure Mechanismsmentioning

confidence: 99%