Characteristics of thermal-structural interaction on organic thin film transistors

Abstract

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.

Organic thin film transistors (OTFTs) on a flexible substrate offer many advantages in the fabrication of low-cost sensors, e-paper, smart cards, and flexible displays. The performance of OTFTs in upper and lower contact structured devices is affected by parameters such as the temperature and field effects. Regarding the key device parameter that affects the performance, the heat transfer and thermal stress of layers are matters of grave concern for maintaining the stability. to this study, we simulated the physical characteristics through coupled thermal, electrical, and structural analysis of OTFTs under various drain-voltage conditions. The electrical characteristics such as current vs. voltage were estimated by the measurement of various temperatures ranging 293 to 393K at a fixed drain voltage (Vsd), viz, either -1 V or -20V. The result shows that because the top layer in an OTFT features poor chemical union and differential thermal expansion coefficients between the Au electrodes and the Pentacene layer, hole mobility increases when the temperature raised from 370K. The analytical model estimated that how much current and increase in temperature displace the layers, because the thermally induced stress loads the material and deforms the OTFTs. As a result, the crystals of the pentacene layer are affected by the specific stress of the relative layers, which causes thermal resistance. Also, the heat-transfer characteristics lead to displacement of layers through the thermal expansion of the OTFTs.