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

Journal article
(Original article)


Publication Details

Author(s): Weber M, Wittmann J, Burger A, Malcioglu O, Segarra-Marti J, Hirsch A, Coto PB, Bockstedte M, Costa RD
Journal: Advanced Functional Materials
Publisher: Wiley-VCH Verlag
Publication year: 2016
Volume: 26
Journal issue: 37
Pages range: 6737-6750
ISSN: 1616-301X
eISSN: 1616-3018


Abstract

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.


FAU Authors / FAU Editors

Burger, Alexandra Dr.
Lehrstuhl für Organische Chemie II
Hirsch, Andreas Prof. Dr.
Lehrstuhl für Organische Chemie II
Malcioglu, Osman Dr.
Lehrstuhl für Theoretische Festkörperphysik
Weber, Michael
Lehrstuhl für Physikalische Chemie I
Wittmann, Judith
Lehrstuhl für Physikalische Chemie I


Additional Organisation
Exzellenz-Cluster Engineering of Advanced Materials


External institutions with authors

University of Bologna / Università di Bologna


Research Fields

B Nanoelectronic Materials
Exzellenz-Cluster Engineering of Advanced Materials
C Photonic and Optical Materials
Exzellenz-Cluster Engineering of Advanced Materials


How to cite

APA:
Weber, M., Wittmann, J., Burger, A., Malcioglu, O., Segarra-Marti, J., Hirsch, A.,... Costa, R.D. (2016). From White to Red: Electric-Field Dependent Chromaticity of Light-Emitting Electrochemical Cells based on Archetypal Porphyrins. Advanced Functional Materials, 26(37), 6737-6750. https://dx.doi.org/10.1002/adfm.201602252

MLA:
Weber, Michael, et al. "From White to Red: Electric-Field Dependent Chromaticity of Light-Emitting Electrochemical Cells based on Archetypal Porphyrins." Advanced Functional Materials 26.37 (2016): 6737-6750.

BibTeX: 

Last updated on 2019-14-03 at 13:03