Comparison of Charge‐Carrier Transport in Thin Films of Spiro‐Linked Compounds and Their Corresponding Parent Compounds

Abstract

The charge‐transport properties of the spiro‐linked compounds 2,2′,7,7′‐tetrakis(diphenylamino)‐9,9′‐spirobifluorene, 2,2′,7,7′‐tetrakis(N,N′‐di‐p‐methylphenylamino)‐9,9′‐spirobifluorene, 2,2′,7,7′‐tetra(m‐tolyl‐phenylamino)‐9,9′‐spirobifluorene, and 2,2′,7,7′‐tetra(N‐phenyl‐1‐naphthylamine)‐9,9′‐spirobifluorene, and their corresponding parent compounds, N,N,N′,N′‐tetraphenylbenzidine, N,N,N′,N′‐tetrakis(4‐methylphenyl)benzidine, and N,N′‐bis(3‐methylphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine, N,N′‐diphenyl‐N,N′‐bis(1‐naphthyl)‐1,1′‐biphenyl‐4,4′‐diamine, are investigated. The field‐effect mobilities of charge carriers in thin films of the parent compounds are slightly higher than those of the spiro‐linked compounds. However, the transistor action of the parent‐compound thin films vanishes because the films crystallize after being stored in ambient atmosphere for a few days. In contrast, the hole mobilities in thin films of the spiro‐linked compounds do not change significantly after the samples are stored in ambient atmosphere for up to nine months. Also discussed is the temperature dependency of the mobilities of charge carriers, which is presented using two models, namely the Arrhenius and the Gaussian disorder models.

Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes

“…MeO-TPD and NPB have very low glass transition temperatures (67 and 95 C, respectively), which is known to lead to undesired crystallization of the material in thin films. 18 Spiro-TTB and BF-DPB instead provide higher stability with glass transition temperatures of 146 and 160 C, respectively. Compared to MeO-TPD and Spiro-TTB, BF-DPB and NPB have higher ionization potentials (IP) (5.23 and 5.4 eV) and BF-DPB and Spiro-TTB provide the highest hole mobility (5.7 Â 10 À5 cm 2 /(V s)).…”

4,4′‐Spirobi[cyclopenta[2,1‐b;3,4‐b′]dithiophene: A New Generation of Heterocyclic Spiro‐Type Molecules

“…field-effect transistors, [9][10][11][12] and lasers. [13][14][15][16][17][18] We recently reported that the charge transport properties in thin films of spiro-linked compounds based on the 9,9′-spirobifluorene core are slightly different with respect to their corresponding parent compounds.…”

Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials

“…These HTMs are standard organic light-emitting diode (OLED) materials due to their superior stability and high glass transition temperatures (T g ). [16,17] The energy levels of the dopant and the hosts are determined using a combination of ultraviolet and inverse photoemission spectroscopy (UPS, IPES). Doping efficiency is assessed through Fermi level shift and current-voltage measurements as a function of incorporated dopant concentration.…”