Simultaneous Improvement of Hole and Electron Injection in Organic Field-effect Transistors by Conjugated Polymer-wrapped Carbon Nanotube Interlayers

Abstract

Efficient charge injection is critical for flexible organic electronic devices such as organic light-emitting diodes (OLEDs) and field-effect transistors (OFETs). Here, we investigated conjugated polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWNTs) as solution-processable charge-injection layers in ambipolar organic field-effect transistors with poly(thienylenevinylene-co-phthalimide)s. The interlayers were prepared using poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) or poly(9,9-dioctylfluorene) (PFO) to wrap s-SWNTs. In the contact-limited ambipolar OFETs, the interlayer led to significantly lower contact resistance (Rc) and increased mobilities for both holes and electrons. The resulting PTVPhI-Eh OFETs with PFO-wrapped s-SWNT interlayers showed very well-balanced ambipolar transport properties with a hole mobility of 0.5 cm2V-1S-1 and an electron mobility of 0.5 cm2V-1S-1 in linear regime. In addition, the chirality of s-SWNTs and kind of wrapping of conjugated polymers are not critical to improving charge-injection properties. We found that the improvements caused by the interlayer were due to the better charge injection at the metal/organic semiconductor contact interface and the increase in the charge concentration through a detailed examination of charge transport with low-temperature measurements. Finally, we successfully demonstrated complementary ambipolar inverters incorporating the interlayers without excessive patterning.

A Novel pH Neutral Self-Doped Polymer for Anode Interfacial Layer in Efficient Polymer Solar Cells

“…Over the past decades, interfacial layer materials have played a critical role in promoting the performance of organic optoelectronic devices, especially for polymer solar cells (PSCs). − In PSCs, interfacial layers help to form ohmic contact between electrodes and active layers, which is of great importance for charge transport and charge collection. − With the rapid progress in interfacial materials and active layer materials, the power conversion efficiencies (PCEs) of PSCs have exceeded the landmark value of 10%. − At present, developing new interfacial materials has become an effective way to improve the photovoltaic performances of PSCs.…”

Thermoelectric Properties of Thermally Reduced Graphene Oxide Observed by Tuning the Energy States

“…According to several reports, the thermoelectric properties of carbon-based materials are determined by the doping state of the materials. , The transfer curve of carbon nanotubes shows an ambipolar shape, − but in an ambient environment (without V g ), the carbon nanotubes are intrinsically in the hole-doped state; in other words, the Seebeck coefficient of intrinsic carbon nanotubes is positive. , The E CNP of graphene or rGO is readily shifted by attaching nanoparticles or silane-based materials. , Moreover, the residual-oxygen functional groups reportedly alter the work function of rGO. , In general, the E CNP and work function of graphene exfoliated from graphite appear at similar positions. However, when the rGO lattice is doped with impurities such as boron or nitrogen atoms, a gap appears between E F and E CNP , which is known as the doping state …”

High-triplet-level phthalimide based acceptors for exciplexes with multicolor emission

“…One of the well-known accepting unit is phthalimide moiety, derivatives of which are used as synthetic precursors for the synthesis of organic semiconductors. Phthalimide derivatives have found applications in optoelectronic and electronic devices such as solar cells [20,21], organic thin-film transistors [22,23] and organic light emitting diodes [24,25]. The main advantages of phthalimides are cheap and simple synthetic synthesis, strong accepting properties (low lying LUMO levels), high triplet energy levels and high thermal stability [20,25,26].…”