Reconfigurable Complementary Logic Circuits with Ambipolar Organic Transistors

Abstract

Ambipolar organic electronics offer great potential for simple and low-cost fabrication of complementary logic circuits on large-area and mechanically flexible substrates. Ambipolar transistors are ideal candidates for the simple and low-cost development of complementary logic circuits since they can operate as n-type and p-type transistors. Nevertheless, the experimental demonstration of ambipolar organic complementary circuits is limited to inverters. The control of the transistor polarity is crucial for proper circuit operation. Novel gating techniques enable to control the transistor polarity but result in dramatically reduced performances. Here we show high-performance non-planar ambipolar organic transistors with electrical control of the polarity and orders of magnitude higher performances with respect to state-of-art split-gate ambipolar transistors. Electrically reconfigurable complementary logic gates based on ambipolar organic transistors are experimentally demonstrated, thus opening up new opportunities for ambipolar organic complementary electronics.

Recent Advances in Ambipolar Transistors for Functional Applications

“…CMOS inverters are basic units in complementary circuits and composed of p‐ and n‐type transistors with symmetric threshold voltages as well as analogous response speed . In the course of work, the two pairs of gate and drain electrodes of p‐ and n‐type transistors are linked together and function as input and output terminals.…”

Top‐Split‐Gate Ambipolar Organic Thin‐Film Transistors

“…Another design approach is implementing a split‐gate ambipolar OTFT . In a split gate device, the polarity of the transistor can be controlled using an additional gate electrode.…”

“…Gate bias stress, a shift in threshold voltage under operation, should be negligible in order to realize robust circuits. Unfortunately, previous works on split‐gate ambipolar OTFTs either showed large hysteresis in I – V characteristics or reported only the forward voltage sweep characteristics without investigating the I – V hysteresis ( Table 1 ). The main reason for the observed gate bias stress in previously reported split‐gate ambipolar OTFTs is that previous devices used the bottom‐gate device geometry based on inorganic oxide dielectric layers such as SiO 2 or Al 2 O 3 .…”

“…Table provides comparisons of the transistor structures, semiconductors, gate configurations, electrical hysteresis behavior, and hole and electron mobility among several split‐gate devices. In addition to the elimination of I – V hysteresis, the proposed top‐gate bottom‐contact device geometry using Cytop buffer provides higher effective carrier mobility for both hole and electron ( µ h = 0.46 cm 2 V −1 s −1 , µ e = 0.1 cm 2 V −1 s −1 ) . The mobility enhancement in the top‐split‐gate ambipolar device compared to bottom‐gate based counterparts mainly comes from the smaller number of charge traps at the dielectric/organic semiconductor interface …”

Hybrid gate dielectrics: a comparative study between polyvinyl alcohol/ $$\hbox {SiO}_{2}$$ SiO 2 nanocomposite and pure polyvinyl alcohol thin-film transistors

“…However, it has been shown that electrons can also be mobile in many conjugated polymers if an appropriate gate dielectric, in most cases polymers, is chosen leading to the n-type behaviour [10]. OTFTs which can operate in both p-type and n-type conduction modes (ambipolar behaviour) are ideal candidates for the simple and low-cost development of complementary like circuits [11]. Polymer dielectrics have recently been used as gate dielectrics in OTFTs due to their simple processing via spin-coating or -casting, and easy tuning of surface chemical properties [12].…”