Electrochemical and Photo-Physical Investigations of Organic Light Emitting Diode Materials
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Abstract
Elektrokjemiske eksperimenter som syklisk voltammetri og elektrokjemisk impedans spektroskopi var utførtfor å finne den høyeste opptatte molekylære orbitalen (HOMO) og den lavest uokkuperte molekylære(LUMO) orbitalen for organiske molekyler. Det ble utført i 99.8% ren N,N-Dimethylformamide (DMF)som løsemiddel med ≥98% 0.1M tetrabutylammonium perchlorate (TBA) som elektrolytt. N,N-Di(1-naphthyl)-N,Ndiphenyl-(1,1-biphenyl)-4,4-diamine (NPD) hadde et målt HOMO nivå på -5.44eV og etLUMO nivå på -2.23eV. Tris(2-phenylpyridine)iridium(III) (Ir(ppy)3) hadde et målt HOMO nivå på -5.38eV. Ferrocene (Fc), som oksiderer på -5.05eV, ble brukt som referanse.Molekylene Platinum octaethylporphyrin (PtOEP), 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphinepalladium(II) (PdOEP), 9,10-Diphenylanthracene (DPA) og Rubrene ble foto-kinetisk analysert. Det spektrale og kinetiske egenskapene til triplett-triplett annihilasjon (TTA) var målt med donator/akseptor parenePtOEP-DPA og PdOEP-Rubrene. Transient absorbsjon og transient emisjon ble spesifikt brukt for å lokalisere triplett absorbsjonen og finne den korresponderende forsinkede fluorescensen. En kinetisk model forsystemet ble foreslått og simulert. Electrochemical experiments such as cyclic voltammetry and electrochemical impedance spectroscopywere used to determine the highest occupied molecular orbital (HOMO) and lowest unoccupied molecluarorbital (LUMO) levels of organic molecules. They were conducted in 99.8% pure N,N-Dimethylformamide(DMF) as solvent with ≥ 98% 0.1M tetrabutylammonium perchlorate (TBA) as supporting electrolyte. N,NDi(1-naphthyl)-N,Ndiphenyl-(1,1-biphenyl)-4,4-diamine (NPD) had a measured HOMO level of -5.44eVand a LUMO level of -2.23eV. Tris(2-phenylpyridine)iridium(III) (Ir(ppy)3) had a measured HOMO levelof -5.38 eV. Ferrocene (Fc), which oxidizes at -5.05eV, was used as reference.The molecules Platinum octaethylporphyrin (PtOEP), 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphinepalladium(II) (PdOEP), 9,10-Diphenylanthracene (DPA) and Rubrene were under photo-kinetic investigation. The spectral and kinetic features of triplet-triplet annihilation were measured from the donor-acceptorpairs PtOEP-DPA and PdOEP-Rubrene. Specifically, transient absorption spectroscopy and transient emission spectroscopy were used to locate the triplet absorption bands and correlate their appearance in timewith the delayed fluorescence. A kinetic model of the system was suggested and simulated of the donor/acceptor pairs and their energy transfers giving rise to the delayed fluorescence.