Solution-processed ambipolar organic field-effect transistors and inverters

Abstract

There is ample evidence that organic field-effect transistors have reached a stage where they can be industrialized, analogous to standard metal oxide semiconductor (MOS) transistors. Monocrystalline silicon technology is largely based on complementary MOS (CMOS) structures that use both n-type and p-type transistor channels. This complementary technology has enabled the construction of digital circuits, which operate with a high robustness, low power dissipation and a good noise margin. For the design of efficient organic integrated circuits, there is an urgent need for complementary technology, where both n-type and p-type transistor operation is realized in a single layer, while maintaining the attractiveness of easy solution processing. We demonstrate, by using solution-processed field-effect transistors, that hole transport and electron transport are both generic properties of organic semiconductors. This ambipolar transport is observed in polymers based on interpenetrating networks as well as in narrow bandgap organic semiconductors. We combine the organic ambipolar transistors into functional CMOS-like inverters.

Organic complementary-like inverters employing methanofullerene-based ambipolar field-effect transistors

“…7 In their work Meijer et al have demonstrated that by employing identical ambipolar OFETs based on polymer-small molecule interpenetrating networks as well as narrow band gap polymers, CMOS-like voltage inverters can be fabricated. This approach makes full use of the attractive processing properties of polymers while it simplifies device fabrication by utilizing a single semiconductor layer.…”

“…However, despite these promising preliminary results there is still a drawback associated with most ambipolar OFETs reported to date, which is the relatively low carrier mobility. [7][8][9][10] For example, in the work by Meijer et al the maximum ambipolar carrier mobilities reported were in the order of 10 −5 cm 2 /V s (for both electrons and holes) for narrow band gap based polymeric OFETs, and 10 −5 cm 2 /V s (electrons) 10 −3 cm 2 /V s (holes) for OFETs based on polymer-small molecule interpenetrating networks. 7 Moreover, Dodabalapur et al have observed that the electron mobility in ambipolar OFETs employing an organic heterostructure of C 60 / ␣-6T is lower by a factor of 16 when compared with the electron mobility measured in pristine C 60 OFETs.…”

“…[7][8][9][10] For example, in the work by Meijer et al the maximum ambipolar carrier mobilities reported were in the order of 10 −5 cm 2 /V s (for both electrons and holes) for narrow band gap based polymeric OFETs, and 10 −5 cm 2 /V s (electrons) 10 −3 cm 2 /V s (holes) for OFETs based on polymer-small molecule interpenetrating networks. 7 Moreover, Dodabalapur et al have observed that the electron mobility in ambipolar OFETs employing an organic heterostructure of C 60 / ␣-6T is lower by a factor of 16 when compared with the electron mobility measured in pristine C 60 OFETs. 8,11 Since carrier mobility is the main limiting factor in the operating frequency of complementary organic circuits, ideally, one would like to have materials with much higher mobilities for both electrons and holes.…”

Organic Light‐Emitting Transistors

“…Such an ambipolar transport is difficult to achieve in a wide-band-gap organic material because of impurity-induced traps [1]. A viable way to circumvent this problem is to mix electron-and hole-transporting moieties into one phase, as was demonstrated with solution processed OFETs [2,3].…”

Organic light emitting complementary inverters

“…13 Integration of organic p-type and n-type transistors in the same device architecture enables a complementary inverter to be made. [14][15][16][17][18][19] This approach simplifies the design and fabrication of logic circuits ͑such as NOR, NAND, and ring oscillators͒. Several methods have been proposed to demonstrate inverters using structures that transport both electrons and holes; e.g., single layer ambipolar /bipolar materials, 16,17 bilayer films, 18 and blends of two components 19 ͑p-and n-type organic semiconductors͒.…”