Carrier Mobility for π-Conjugated Dendrimer Composed of Phenylene-vinylene Dendron and Triphenylamine Surface Group

Abstract

Carrier transport property of-conjugated dendrimer is of current scientific and technological interest because of a molecular architecture for organic semiconductor materials and because of a variety of practical applications such as light emitting diodes, thin film transistors, and photo-voltaic cells. 1-6 Previously, we reported the carrier transport property of the soluble-conjugated three-generation dendrimer which is composed of phenylene-vinylene as a dendron group and triphenylamine as a soluble surface group (G3D3-PV(TPA)) as shown in Figure 1b. 7 The carrier of transporting across the G3D3-PV(TPA) dendrimer film was preferentially hole with an indium-tin-oxide (ITO)/G3D3-PV(TPA)/Mg-Al cell. The Mg-Al is the opposite electrode composed of alloy of Mg and Al. The hole mobility was 10 À5 (cm 2 /(VÁs)) order at 25 C, which is the same order as that of poly(p-phenylene-vinylene) reported by Lebedev and co-workers though the dendrimer is surrounded by the triphenylamine surface group. 8 According to the results reported previously, the triphenylamine surface group covalently attached to the dendron did not show the carrier transport property. 7 This result indicates that the phenylene-vinylene molecules with different dendrimer are comparably close to each other. We have estimated the structure of the G3D3-PV(TPA) dendrimer was comparably planar shape rather than globular shape. 7

A time-of-flight study of a new hyperbranched oligomer film composed of thiophene and N,N,N′,N′-tetraphenyl-1,3-phenylenediamine

“…5 For improving both solubility and carrier transport property, we were successful in designing p-conjugated soluble dendrimers, as reported in our earlier paper. 10,11 The dendrimers are composed of p-conjugated p-phenylenevinylene dendrons surrounded by triphenylamine surface groups. 10,11 The carrier mobility for the dendrimer film prepared by a spin-coating technique increased when the generation number of the p-phenylenevinylene group was decreased.…”

“…10,11 The dendrimers are composed of p-conjugated p-phenylenevinylene dendrons surrounded by triphenylamine surface groups. 10,11 The carrier mobility for the dendrimer film prepared by a spin-coating technique increased when the generation number of the p-phenylenevinylene group was decreased. 11 The hole mobility for the film of a two-generation dendrimer attained an order of 10 À4 cm 2 (VÁs) À1 at 25 1C, whereas that of a three-generation dendrimer was in an order of 10 À5 cm 2 (VÁs) À1 , as determined by a time-of-flight (TOF) method.…”

“…10,11 The carrier mobility for the dendrimer film prepared by a spin-coating technique increased when the generation number of the p-phenylenevinylene group was decreased. 11 The hole mobility for the film of a two-generation dendrimer attained an order of 10 À4 cm 2 (VÁs) À1 at 25 1C, whereas that of a three-generation dendrimer was in an order of 10 À5 cm 2 (VÁs) À1 , as determined by a time-of-flight (TOF) method. 11 Meier et al 12 reported that the molecular structure of the p-phenylenevinylene dendrimer surrounded by the alkyloxy groups becomes planar in shape with two-generation of p-phenylenevinylene.…”

“…11 The hole mobility for the film of a two-generation dendrimer attained an order of 10 À4 cm 2 (VÁs) À1 at 25 1C, whereas that of a three-generation dendrimer was in an order of 10 À5 cm 2 (VÁs) À1 , as determined by a time-of-flight (TOF) method. 11 Meier et al 12 reported that the molecular structure of the p-phenylenevinylene dendrimer surrounded by the alkyloxy groups becomes planar in shape with two-generation of p-phenylenevinylene. Thus, we can assume that the molecular structure of the two-generation dendrimer we prepared is planar in shape.…”

“…Thus, we can assume that the molecular structure of the two-generation dendrimer we prepared is planar in shape. 11 In the case of the planar-shaped dendrimer, one can estimate that carrier hopping occurs easily as the distance between the p-conjugated groups of the different dendrimer molecules becomes comparably short. From the results of our earlier work, it can be anticipated that the p-conjugated soluble dendrimer is a candidate for practical use.…”