Impedance spectroscopy of OLEDs as a tool for estimating mobility and the concentration of charge carriers in transport layers

Chulkin, P., Vybornyi, O., Lapkowski, M., Skabara, P.J. and Data, P. (2018) Impedance spectroscopy of OLEDs as a tool for estimating mobility and the concentration of charge carriers in transport layers. Journal of Materials Chemistry C, 6(5), pp. 1008-1014. (doi: 10.1039/C7TC04599A)

Abstract

The article presents a novel impedance spectroscopy based technique designed to characterise organic light emitting diodes (OLED) during operation. A number of devices based on NPB (N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine) and TPBi (2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) conducting layers, CBP (4,4′-bis(N-carbazolyl)-1,1′-biphenyl) as a host and BPTZ-DBTO2 (3,6-bis(10H-phenothiazine-10-yl)-9H-fluorene-[dibenzothiophene-S,S-dioxide]) as an emitter were taken as an example to validate the method. Using equivalent electrical circuits, values of capacitance and conductivity of both hole- (HTL) and electron-transport (ETL) layers were determined and analysed separately. Those parameters, as well as current–voltage characteristics, were used to calculate (i) mobility (μ, cm2 V−1 s−1) of both types of charge carriers, (ii) charge density (n, cm−3) of the charge carriers, and (iii) electric field intensity (E, V m−1) in both transport layers as functions of the applied voltage.

• Item Type: Articles
• Additional Information: The authors gratefully acknowledge the financial support of project Excilight: Donor–Acceptor Light Emitting Exciplexes as Materials for Easy-to-tailor Ultra-efficient OLED Lightning (H2020-MSCA-ITN-2015/674990) financed by Marie SklodowskaCurie Actions within the framework programme for research and innovations Horizon2020.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vybornyi, Mr Oleh and Skabara, Professor Peter
• Authors: Chulkin, P., Vybornyi, O., Lapkowski, M., Skabara, P.J., and Data, P.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Journal of Materials Chemistry C
• Publisher: Royal Society of Chemistry
• ISSN: 2050-7526
• ISSN (Online): 2050-7534
• Published Online: 01 January 2018