| STRUCTURE |
The material, a dimethyloctane (dmoc) compound, [Pt(NH2dmoc)4][PtCl4], has a one-dimensional chain structure with a backbone of linearly arranged platinum atoms. It is based on Magnus' green salt, [Pt(NH3)4][PtCl4], first reported in 1828 by German scientist Heinrich Gustav Magnus (1802–70). |
| PROPERTIES |
[Pt(NH2dmoc)4][PtCl4]--a green, crystalline material that is thermally stable to over 130 °C--is highly soluble at around 70 to 80 °C in a range of solvents, including toluene, trichloroethane, and xylene. The platinum compound can be easily recrystallized under ambient conditions. "This very desirable property makes it possible to readily form films, fibers by electrostatic spinning, blends with polymers, and other structures," the authors note |
| SYNTHESIS |
A platinum-based organometallic material synthesized by scientists in Europe offers a promising solution to the problem of poor environmental stability that is suffered by virtually all known semiconducting organic polymers and layered organic-inorganic hybrid materials. "Our work addresses the old, but not always openly exposed, problem of the environmental stability of popular organic semiconductors," ETH professor of polymer technology Paul Smith tells C&EN. "Typically, these materials are manufactured and processed into devices in dry-boxes, in the absence of white light, air, and/or water. Also, once incorporated in devices, elaborate packaging is often applied to increase their lifetime. "We synthesized the semiconducting platinum-based chain structures in aqueous media and processed them from simple organic solvents in air to make oriented thin films, fibers, and field-effect transistors," he continues. "We found that the materials can be exposed to white light and air for six months or more without significant loss of their semiconducting characteristics." THE PLATINUM MATERIALS can withstand extremely harsh conditions. Even "cooking" in hot water at 80 to 90 °C for periods of 12 hours or so does not lead to significant loss of performance. "This treatment even improves the on-off switching ratios of field-effect transistors by a factor of 10 or more," Smith says. "We realize that our materials and devices do not yet exhibit outstanding semiconducting characteristics such as charge mobility. However, we see this effort as a start toward a class of environmentally stable, readily processible compounds that, because of their simple chemistry, could include a broad spectrum of additional functionalities." The team synthesized compounds of the type [Pt(NH2R)4][PtCl4], where R is a linear or branched alkyl group, by adding K2[PtCl4] to a solution of the selected amine compound in water. The products were extracted using a solvent such as toluene. |
| UPDATE | 03.03 |
| USES | They used [Pt(NH2dmoc)4][PtCl4] as the active semiconductor layer to produce field-effect transistors under ambient conditions in air. By using poly(tetrafluoroethylene) orientation layers, they were able to align the platinum chain structures parallel to the current transport direction exhibited by p-type transistor action and to determine the field-effect mobilities of the devices. They attributed the mobility to the injection of holes into a valence band based on platinum d-orbitals delocalized along the polymer axis. The team, however, was unable to obtain n-type transistor operation using the platinum compound |
| AUTHOR |
- Center for Research on Plant Macromolecules - Delft University - Eindhoven University - Swiss Federal Institute of Technology (Smith Paul) - University of Cambridge |
| LITERATURE REF. | [Adv. Mater., 15, 125 (2003)]. |
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