Method for the production and configuration of organic field-effect transistors (ofet)

#The invention relates to a method for producing and patterning organic field-effect transistors (OFETs).

#Polymeric integrated circuits based on OFETs are used for microelectronic mass applications and disposal products such as identification and product tags. A tag is e.g. an electronic bar code of the kind provided on merchandise or on luggage. In this case, the excellent operating behavior of silicon technology can be dispensed with, but by the same token low producing costs and mechanical flexibility should be ensured. The devices such as e.g. electronic bar codes are typically disposable products and are of interest economically only if they are produced in inexpensive processes.

#To date, owing to the production costs, only the conductor layer of the OFET has been patterned since the patterning can only be realized using a two-stage process (“lithography method” cf. in this respect Applied Physics Letters 73(1), 1998, p. 108.110 and Mol. Cryst. Liq. Cryst. 189, 1990 p. 221-225) with firstly whole-area coating and subsequent patterning, which is material-specific, moreover. “Material specificity” means that the process described, with the photochemical components mentioned, only functions on the conductive polymer polyaniline. A different conductive polymer, e.g. polypyrrol, cannot readily be patterned in this way.

#The invention will be explained in more detail below using an exemplary embodiment.

#FIGS. 1 to 7 show the individual process steps of pad printing by a continuous method using a pad roll.

#Firstly, the block 1 with the negatives 2 of the structure to be applied is shown in FIG. 1. Before the negative imprinting, it is possible to discern a doctor blade 3, which applies the functional polymer 4 along the block by blade. In FIG. 2, the negative 2 of the block is filled with functional polymer 4 and the doctor blade continues to slide precisely with the remainder of polymer on the block 1, which can rotate, for example. FIG. 3 reveals the large pad roll 5, which takes up the finished patterned functional polymer 4 from the block 3 and (cf. FIGS. 4 to 7) images it onto a substrate 6. The finished applied and patterned OFET 7 can be seen in FIG. 7.

#The invention provides a cost-effective and precise method for producing and patterning OFETs by utilizing the solubility of at least one functional polymer of an OFET insofar as the functional polymer is applied to the prepared OFET or a substrate like an ink by means of a conventional printing method. The production method can be used for the cost-effective production of product and/or identification tags.

#In contrast to the conventional method, by means of which only the conductor layer of an OFET can be patterned and the other layers of the OFET remain unpatterned, the printing process proposed by the invention is not material-specific, i.e. any arbitrary conductive polymer can be printed. Thus, both polyaniline and polypyrrol and further conductive polymers can be patterned with the aid of the printing method onto the substrate for the purpose of forming the OFET. The “lithography method” does not make sense for patterning the nonconductive layers of the organic transistor (semiconductor and insulator), for cost reasons. Only the printing according to the invention is actually appropriate here, for lack of other patterning methods.