From White to Red: Electric-Field Dependent Chromaticity of Light-Emitting Electrochemical Cells based on Archetypal Porphyrins

Weber, Michael D.
Wittmann, Judith E.
Burger, Alexandra
Malcıoğlu, Osman Barış
Segarra-Marti, Javier
Hirsch, Andreas
Coto, Pedro B.
Bockstedte, Michel
Costa, Ruben D.
The differences in the electroluminescence (EL) of red-emitting free-base (H2TPP) and Zn-metalated (ZnTPP) archetypal porphyrins are rationalized in light-emitting electrochemical cells by means of an electric-field dependent effect, leading to whitish and reddish devices, respectively. Although H2TPP shows superior electrochemical and photophysical features compared to ZnTPP, devices prepared with ZnTPP surprisingly stand out with a deep-red EL similar to its photoluminescence (PL), while H2TPP devices feature unexpected whitish EL. Standard arguments such as degradation, device architecture, device mechanism, and changes in the nature of the emitting excited states are discarded. Based on electrochemical impedance spectroscopy and first-principles electronic structure methods, we provide evidence that the EL originates from two H2TPP regioisomers, in which the inner ring H atoms are placed in collinear and vicinal configurations. The combination of their optical features provides an explanation for both the high-and low-energy EL features. Here, the emitting excited state nature is ascribed to the Q bands, since the Soret excited states remain high in energy. This contrasts to what is traditionally postulated in reports focused on H2TPP lighting devices. Hence, this work provides a new explanation for the nature of the high-energy EL band of H2TPP that might inspire future works focused on white-emitting molecular-based devices.


From Homoconjugated Push-Pull Chromophores to Donor-Acceptor-Substituted Spiro Systems by Thermal Rearrangement
Dengiz, Çağatay; KATO, Shin-ichiro; ZALIBERA, Michal; CIAS, Pawel; SCHWEIZER, W. Bernd; BOUDON, Corinne; GISSELBRECHT, Jean-Paul; GESCHEIDT, Georg; DIEDERICH, Francois (Wiley, 2014-01-27)
Series of homoconjugated push-pull chromophores and donor-acceptor (D-A)-functionalized spiro compounds were synthesized, in which the electron-donating strength of the anilino donor groups was systematically varied. The structural and optoelectronic properties of the compounds were investigated by X-ray analysis, UV/Vis spectroscopy, electrochemistry, and computational analysis. The homoconjugated push-pull chromophores with a central bicyclo[4.2.0]octane scaffold were obtained in high yield by [2+2] cyclo...
A blue to highly transmissive soluble electrochromic polymer based on poly(3,4-propylenedioxyselenophene) with a high stability and coloration efficiency
Ozkut, Merve Icli; Atak, Samed; Önal, Ahmet Muhtar; CİHANER, ATİLLA (2011-01-01)
The optical and electrochemical properties of a regioregular and soluble alkylenedioxyselenophene-based electrochromic polymer, namely poly(3,3-didecyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4] dioxepine (PProDOS-C-10), which is synthesized by electrochemical polymerization, are highlighted. It is noted that this unique polymer has a low band gap (1.58 eV) and is exceptionally stable under ambient atmospheric conditions. Polymer films retain 97% of their electroactivity after 40 000 cycles. The percentage tran...
Photo- and electroluminescent properties of a π-conjugated copolymer containing 2,2′-bipyridyl units
Deichmann, Vitor Angelo Fonseca; Çırpan, Ali; KARASZ, Frank E.; AKCELRUD, Leni (Wiley, 2007-02-01)
The synthesis, structural characteristics, and photo- and electroluminescent properties of a soluble light-emitting copolymer built up of regularly alternating segments of 1,4-dihexyloxybenzene and 2,2'-bipyridyl (PBPyDHB) are described and discussed. Optical properties of the polymer were investigated in solution and solid-state conditions, demonstrating that in film form the predominant emission centers are inter-macromolecular aggregates, either in photo- or electroluminescence. Thermogravimetric analysi...
Stereoselective synthesis of spirocyclic cyclopentapyrans by the Pauson-Khand reaction on camphor tethered enynes
Sezer, Serdar; Gumrukcu, Yasemin; ŞAHİN, Ertan; Tanyeli, Cihangir (2008-12-01)
An intramolecular Pauson-Khand reaction of camphor tethered enynes derived from homoallyl, homomethallyl and homopropargyl alcohols is described. Homoallyl, homomethallyl, and homopropargyl moieties are easily constructed on the camphor carbonyl group with excellent diastereoselectivity due to endo-face selectivity, and with known stereochemistry. Each enantiomerically pure enyne affords the conformationally most stable diastereomeric spirocyclic cyclopenta[c]pyran ring system.
Synthesis and electrochemical studies of fluorene and benzimidazole containing conjugated polymers
Namal, İmge; Toppare, Levent Kamil; Arslan Udum, Yasemin; Department of Chemistry (2013)
The synthesis and characterization of two donor acceptor type conjugated polymers were investigated. The electrochemical properties were examined using cyclic voltammetry, spectroelectrochemistry and kinetic studies. The increase in the alkyl chain length attached to the fluorene unit was investigated by the corresponding electrochemical characteristics. The synthesis was carried out via Stille coupling of 4,7- dibromo-4'-(tert-butyl)spiro[benzo[d]imidazole-2,1' cyclohexane] and 2,5- bis(tributylstannyl)thi...
Citation Formats
M. D. Weber et al., “From White to Red: Electric-Field Dependent Chromaticity of Light-Emitting Electrochemical Cells based on Archetypal Porphyrins,” ADVANCED FUNCTIONAL MATERIALS, pp. 6737–6750, 2016, Accessed: 00, 2020. [Online]. Available: