Year

2017

Type(s)

Journal Article

Author(s)

Chulkin, P. and Lapkowski, M. and Bryce, M.R. and Santos, J. and Data, P.

Source

Electrochimica Acta, 258: 1160—1172, 2017

Url

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035313615&doi=10.1016%2fj.electacta.2017.11.171&partnerID=40&md5=5be0bfb959a9995c2c1a16d6582f6412

BibTeX

BibTeX

BibTeX

@ARTICLE{Chulkin20171160, author={Chulkin, P. and Lapkowski, M. and Bryce, M.R. and Santos, J. and Data, P.}, title={Determination of standard redox rate constants of OLED active compounds by electrochemical impedance spectroscopy}, journal={Electrochimica Acta}, year={2017}, volume={258}, pages={1160-1172}, doi={10.1016/j.electacta.2017.11.171}, note={cited By 4}, url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035313615&doi=10.1016%2fj.electacta.2017.11.171&partnerID=40&md5=5be0bfb959a9995c2c1a16d6582f6412}, affiliation={Silesian University of Technology, Faculty of Chemistry, Department of Physical Chemistry and Technology of Polymers, Strzody 9, Gliwice, 44-100, Poland; Centre of Polymer and Carbon Materials of the Polish Academy of Sciences, Zabrze, Poland; Durham University, Department of Chemistry, South Road, Durham, DH1 3LE, United Kingdom; Durham University, Department of Physics, South Road, Durham, DH1 3LE, United Kingdom}, abstract={A number of commercial organic compounds (m-MTDATA, PBD, CBP, TAPC, NPB, TPBi, etc) as well as several donor-acceptor-donor (D-A-D) compounds were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The compounds were chosen as they are promising components of small-molecule-based high efficiency Thermally Activated Delayed Fluorescence (TADF) emitters in Organic Light Emitting Diodes (OLEDs). Electrochemical impedance spectra of a Pt electrode in CH2Cl2 solutions containing the investigated compound and Bu4NBF4 as the electrolyte were obtained and analyzed by electrochemical electrical circuit methods. Charge transfer resistance, double layer capacitance, Warburg constant and other parameters were determined and represented as a function of the potential. Analysis of charge transfer resistance as a function of potential allowed an estimation of standard redox rate constants for the compounds’ oxidation and reduction processes. Two main features concerning the redox reaction rates of OLED-active compounds were revealed: (i) the oxidation and reduction rates of ambipolar compounds, i.e. containing both donor and acceptor parts, were found to be much higher than those of unipolar donor-only and acceptor-only molecules; (ii) the relationship between the oxidation and reduction rate constants was shown to be related to the compounds’ conductivity type in the solid state. © 2017 The Authors}, author_keywords={Acceptor; Ambipolar; Donor; Electrochemical impedance spectroscopy; Exciplex; OLED; Standard redox rate constant; TADF}, keywords={Charge transfer; Chlorine compounds; Cyclic voltammetry; Electric network analysis; Electrochemical electrodes; Electrochemical impedance spectroscopy; Electrolytes; Fluorescence; Light emitting diodes; Molecules; Organic light emitting diodes (OLED); Oxidation; Reaction rates; Redox reactions; Reduction; Spectroscopy, Acceptor; Ambipolar; Donor; Exciplexes; OLED; TADF, Rate constants}, funding_details={H2020 Marie Skłodowska-Curie ActionsH2020 Marie Skłodowska-Curie Actions, MSCA}, funding_details={Engineering and Physical Sciences Research CouncilEngineering and Physical Sciences Research Council, EPSRC, EP/L02621X/1}, funding_text 1={The authors gratefully acknowledge financial support of “Excilight” project “Donor-Acceptor Light Emitting Exciplexes as Materials for Easy-to-tailor Ultra-efficient OLED Lightning” ( H2020-MSCA-ITN-2015/674990 ) funded by Marie Skłodowska-Curie Actions within the framework programme for research and innovations “Horizon-2020”. J.S. and M.R.B. thank EPSRC grant number EP/L02621X/1 for funding.}, references={Organic electronics (2015) ChemPhysChem, 16, pp. 1097-1305; Pei, J., Yu, W.-L., Ni, J., Lai, Y.-H., Huang, W., Heeger, A.J., Thiophene-based conjugated polymers for light-emitting Diodes:  effect of Aryl groups on photoluminescence efficiency and redox behavior (2001) Macromolecules, 34, p. 7241; Lapkowski, M., Data, P., Golba, S., Soloducho, J., Nowakowska-Oleksy, A., Unusual band-gap migration of N-alkylcarbazole-thiophene derivative (2011) Opt. Mater, 22, p. 1445; Trasatti, S., The absolute electrode potential: an explanatory note (1986) Pure Appl. Chem., 58, p. 955; Data, P., Lapkowski, M., Motyka, R., Suwinski, J., Influence of heteroaryl group on electrochemical and spectroscopic properties of conjugated polymers (2012) Electrochim. Acta, 83, p. 271; Data, P., Pander, P., Lapkowski, M., Swist, A., Soloducho, J., Reghu, R.R., Grazulevicius, J.V., Unusual properties of electropolymerized 2,7-and 3,6-carbazole derivatives (2014) Electrochim. Acta, 128, p. 430; Bredas, J.L., Mind the gap! (2014) Mater. Horiz., 1, p. 17; Etherington, M., Franchello, F., Gibson, J., Northley, T., Santos, J., Ward, J., Higginbotham, H., Monkman, A., Regio- and conformational isomerization critical to design of efficient thermally-activated delayed fluorescence emitters (2017) Nat. Commun.; Dias, F.B., Santos, J., Graves, D., Data, P., Nobuyasu, R., Fox, M.A., Palmeira, T., Monkman, A., The role of local triplet excited states in thermally-activated delayed fluorescence: photophysics and devices (2016) Adv. Sci., 3, p. 1600080; Jankus, V., Data, P., Graves, D., McGuinness, C., Santos, J., Bryce, M.R., Dias, F.B., Monkman, A.P., Highly efficient TADF OLEDs: how the emitter–host interaction controls both the excited state species and electrical properties of the devices to achieve near 100% triplet harvesting and high efficiency (2014) Adv. Funct. Mater., 24, p. 6178; Dias, F., Bourdakos, K., Jankus, V., Moss, K., Kamtekar, K., Bhalla, V., Santos, J., Monkman, A.P., Triplet harvesting with 100% efficiency by way of thermally activated delayed fluorescence in charge transfer OLED emitters (2013) Adv. Mater., 25, p. 3707; Data, P., Motyka, R., Lapkowski, M., Suwinski, J., Jursenas, S., Kreiza, G., Miasojedovas, A., Monkman, A.P., Efficient p-phenylene based OLEDs with mixed interfacial exciplex emission (2015) Electrochim. Acta, 182, p. 524; Data, P., Swist, A., Lapkowski, M., Soloducho, J., Darowicki, K., Monkman, A.P., Evidence for solid state electrochemical degradation within a small molecule OLED (2015) Electrochim. Acta, 184, p. 86; Jankus, V., Chiang, C.-J., Dias, F., Monkman, A.P., Deep blue exciplex organic light-emitting diodes with enhanced efficiency; P-type or E-type triplet conversion to singlet excitons? (2013) Adv. Mater., 25, p. 1455; dos Santos, P., Ward, J., Bryce, M.R., Monkman, A.P., Using guest host interactions to optimise the efficiency of TADF-OLEDs (2016) J. Phys. Chem. Lett., 7, p. 3341; Goushi, K., Yoshida, K., Sato, K., Adachi, C., Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion (2012) Nat. Photonics, 6, p. 253; Wang, J., Gou, J., Li, W., Phosphorescent molecularly doped light-emitting diodes with blended polymer host and wide emission spectra (2013) Sci. World J., , 954146, 2013, 5, doi; Wong, M., Zysman-Colman, E., Purely organic thermally activated delayed fluorescence materials for organic light-emitting diodes (2017) Adv. Mater.; Cho, Y.J., Yook, K.S., Lee, J.Y., High efficiency in a solution-processed thermally activated delayed-fluorescence device using a delayed-fluorescence emitting material with improved solubility (2014) Adv. Mater., 26, p. 6642; Ragoisha, G.A., Bondarenko, A.S., http://www.abc.chemistry.bsu.by/vi/analyser, EIS spectrum analyser; Barsoukov, E., Macdonald, J.R., Impedance Spectroscopy: Theory, Experiment, and Applications (2005), second ed. Wiley; Orazem, M.E., Tribollet, B., Electrochemical Impedance Spectroscopy (2008), Wiley; Lasia, A., Electrochemical Impedance Spectroscopy and its Applications (2014), Springer; Bard, A.J., Faulkner, L.R., Electrochemical Methods: Fundamentals and Applications (2001), p. 864. , second ed. Wiley; Brütting, W., Berleb, S., Mückel, A.G., Device physics of organic light-emitting diodes based on molecular materials (2001) Org. Electron, 2, p. 1; Nowy, S., Ren, W., Elschner, A., Lövenich, W., Brütting, W., Impedance spectroscopy as a probe for the degradation of organic light-emitting diodes (2010) J. Appl. Phys., 107}, correspondence_address1={Data, P.; Silesian University of Technology, Faculty of Chemistry, Department of Physical Chemistry and Technology of Polymers, Strzody 9, Poland; email: Przemyslaw.Data@durham.ac.uk}, publisher={Elsevier Ltd}, issn={00134686}, coden={ELCAA}, language={English}, abbrev_source_title={Electrochim Acta}, document_type={Article}, source={Scopus},