Electrical properties of highly ordered and amorphous thin films of pentacene doped with iodineStructural studies on highly conductive thin tlhns of pentacene (PEN) were carried out by x-ray and electron diffraction methods. The ultrathin film before and after doping with iodine was confirmed to consist of single crystalline domains, and the lattice parameters were determined. Drastic elongation along the c axis as a result of doping was observed, while the u-b plane did not change during doping. The intercalation of iodine molecules between molecular layers of PEN was confirmed. 5220

We have demonstrated the iodine doping of vacuum-deposited pentacene (PEN) film which showed characteristic changes in structure and electrical conductivity. The iodine-doped film exhibited a high electrical conductivity of 110 Ω−1 cm−1, which was 11 orders of magnitude larger than that of as-deposited film, and a high electrical anisotropy of 108. The structural changes by the iodine doping were studied by means of x-ray diffraction method, ultraviolet-VIS absorption spectroscopy, and FT-infrared spectroscopy. These results revealed that iodine molecules were intercalated between the layers of PEN molecules to form charge transfer complex of PEN-iodine with highly ordered structure.

Electrical properties of highly ordered and amorphous thin films of pentacene doped with iodine

Studies on electrical properties of highly ordered and amorphous thin films of pentacene (PEN) doped with iodine have been made. Highly ordered film heavily doped with iodine (PEN1I2.2) showed electrical conductivity of 150 Ω−1 cm−1 with a hole mobility of 0.2 to 1 cm2 V−1 s−1 at room temperature. Metallic temperature dependence of the conductivity of the film from 240 to 4 K was observed as the first metallic transport phenomenon ever noted in an acenic compound. In contrast, amorphous film of PEN doped with iodine showed a conductivity of 10−3 Ω−1 cm−1 with an estimated hole mobility of 2×10−5 cm2 V−1 s−1 and semiconductive transport. These results revealed that the electrical properties of PEN thin films are strongly correlated with the degree of molecular orientation.

A novel microchip-sized InSb photodiode infrared sensor (InSb PDS) operating at room temperature is reported. There is no power consumption on the InSb PDS itself, since it works in photovoltaic mode to output an open-circuit voltage. The InSb PDS has a typical responsivity of 1,900 V/W and an output noise of 0.15 µV/Hz 1/2 . A detectivity (D * ) of 2.8x10 8 cmHz 1/2 /W has been obtained at 300 K. The InSb PDS is finally molded with plastic on a Quad Flat Non-leaded (QFN) package, having performance high enough for applications such as mobile electronic equipments, personal computers and consumer electronics.