Silviu Grecu
Charge transport in polymeric field-effect devices
Supervisor: Prof. Dr. W. Brütting [Experimental physics IV]
Date of oral examination: 01/23/2009
In the last years organic semiconductor based devices have made the step from the laboratory to the market in mobile telephones displays or RF-ID tags, becoming more and more present in everyday life devices. The scope of this thesis is to investigate the influence of preparation on the electrical properties of poly(3-hexyl)thiophene in different devices (field-effect transistors, metal-insulator semiconductor diodes and hole-only diodes). Firstly the influence of various organic and inorganic insulators is analyzed. Another important issue is the modification of the silicon oxide surface energy through self-assembled monolayers, thus promoting a better self-organization of the P3HT molecules during the film formation. The last but not the least important process which leads to an improvement of the electrical characteristics of FETs and MIS diodes is the post spin-coating annealing. At the same time special attention will be given to the influence of external parameters as temperature, light and environment upon the operation of these devices. A comparison of our data with existing models describing the charge transport will be attempted in the end.