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Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials
Author(s) -
Zhang Fengyu,
Kahn Antoine
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201703780
Subject(s) - dopant , materials science , ionization energy , doping , ionization , electron affinity (data page) , analytical chemistry (journal) , oxidizing agent , chemical physics , molecule , optoelectronics , organic chemistry , chemistry , ion
2,2′‐(perfluoronaphthalene‐2,6‐diylidene)dimalononitrile (F6‐TCNNQ) is investigated as a molecular p‐type dopant in two hole‐transport materials, 2,2′,7,7′‐tetrakis( N , N ‐diphenylamino)‐9,9‐spirobifluorene (Spiro‐TAD) and tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA). The electron affinity of F6‐TCNNQ is determined to be 5.60 eV, one of the strongest organic molecular oxidizing agents used to date in organic electronics. p‐Doping is found to be effective in Spiro‐TAD (ionization energy = 5.46 eV) but not in TCTA (ionization energy = 5.85 eV). Optical absorption measurements demonstrate that charge transfer is the predominant doping mechanism in Spiro‐TAD:F6‐TCNNQ. The host–dopant interaction also leads to a significant alteration of the host film morphology. Finally, transport measurements done on Spiro‐TAD:F6‐TCNNQ as a function of dopant concentration and temperature, and using a highly doped contact layer to ensure negligible hole injection barrier, lead to an accurate measurement of the film conductivity and hole‐hopping activation energy.