Maria Cristina Tanese

Organic thin-film transistor sensors: Interface dependent and gate bias enhanced responses

Organic thin film transistors are a new class of sensors potentially capable of outperforming chemiresistors. They can be operated at room temperature, offer the advantage of remarkable response repeatability and can function as multi-parameter sensors. In this paper, evidence of OTFT response dependence on important parameters such as the chemical nature of the organic semiconductor active layer and the gate-dielectric/organic-semiconductor interface are produced. A sizable response enhancement of an OTFT sensor operated in the enhancement mode is also presented indicating that an OTFT can in principle lead to a lower detection limit than a resistor-type sensor with the same organic semiconductor.

Synthesis and field-effect properties of α,ω -disubstituted sexithiophenes bearing polar groups

The synthesis of sexithiophenes bearing amide or ester groups in the α,ω-terminal positions is described, along with their characterization in the solid state. The influence of the functional group on mobilities and on/off ratios of the organic FET devices was investigated. The oligomer bearing the ester functional group separated from the sexithiophene core by an ethylene spacer showed a hole field-effect mobility as high as 0.012 cm2 V−1 s−1, which is among the highest reported so far for organic FETs using sexithiophenes modified with polar groups.

A poly(phenyleneethynylene) polymer bearing amino acid substituents as active layer in enantioselective solid-state sensors

A poly(phenyleneethynylene) polymer bearing amino acid pendant groups is used as enantioselective active layer in solid-state sensing devices. The chiral analyte in the present study is menthol in both the natural (-) and synthetic (+) enantiomers. The polymer bearing amino acid chiral sites is demonstrated to interact more favorably with the natural menthol than the synthetic one in a quartz crystal microbalance revealing system. Promising perspectives are seen for the use of such polymers in chiral discriminating, chemically sensitive resistors or even transistors.

High performance organic thin film transistor sensors

Sensitivity is a key issue in designing high performance organic based chemical and biological sensors. Several strategies have been adopted in the past to improve this important figure of merit. In this paper, a pentacene based organic thin film transistor is operated as an alcohol sensor and it is demonstrated that the sensitivity is enhanced when the device works in the accumulation mode.

Chemical design, synthesis and thin film supramolecular architecture for advanced performance chemo- and bio-sensing organic field effect transistors

Organic thin film transistor (OTFT) sensors are capable of fast, sensitive and reliable detection of various classes of chemical and biological analytes with high selectivity, and display the additional advantage of being compatible with plastic electronic technologies. Their distinctive versatility is based on multilevel control of the properties, from molecular design up to device architecture. Here Phenylene-thiophene based semiconductors functionalized with bio-molecules have been synthesized to be used as active layers in sensing OTFTs. These materials, indeed, combine the recognition capability of bio-molecules with the electronic properties of the conjugated backbone. The resulting OTFTs have been used to perform chemical recognition of citronellol obtaining detection limit in the ppm range.

Oligothiophenes bearing polar groups for organic thin film transistors: synthesis, characterisation and preliminary gas sensing results

The properties of a series of sexithiophenes bearing amide or ester functionalities in the alpha,omega-positions are reported. Isolation of the ester functionalities from the sexithiophene core by an ethylene spacer led to a device with moderate hole mobilities (1.2-10-2 cm2V-1s-1) and on/off ratios (103). A bottom contact device based on this sexithiophene showed a good response to a 5 ppm NO atmosphere, encouraging future studies on gas sensing OTFT based on these polar-functionalised OTFT.

Tailored conjugated polymer Langmuir-Schäfer thin films in sensing transistors

Organic Thin Film Transistors (OTFTs) have been fabricated, in a standard bottom gate configuration, with Langmuir-Schafer (LS) or cast thin films of regioregular poly[1,4-(2,5-dioctyloxyphenylene)-2,5-thiophene], synthesized via an organometallic protocol, as active layers. The transistors electrical characterization has evidenced that LS based devices exhibit better performance level than cast film ones. Appealing perspectives for newly substituted conjugated polymers in OTFT sensing devices are discussed.

Polycrystalline organic thin film transistors for advanced chemical sensing

Organic thin-film transistors have seen a dramatic improvement of their performance in the last decade. They have been also proposed as gas sensors. This paper deals with the interesting new aspects that polycrystalline based conducting polymer transistors present when operated as chemical sensors. Such devices are capable to deliver multi-parameter responses that are also extremely repeatable and fast at room temperature. Interesting are also the perspectives for their use as chemically selective devices in array type sensing systems.