Is thermal annealing a viable alternative for crystallisation in triethylsilylethynyl anthradithiophene organic transistors?

Abstract

Triethylsilylethynyl anthradithiophene (TESADT) holds considerable promise for organic transistor applications due to the high electrical mobilities attained by post-deposition crystallisation using solvent vapour annealing. We have studied thermal annealing as an alternative route to post-deposition crystallisation of TESADT films. Thermal annealing initially appears promising, producing mm-sized crystal domains, but poor electrical performance is obtained, which we attribute to a combination of crack formation and potentially also a structural transition during the anneal process. We also find that illumination has a significant positive effect on crystallisation, possibly due to an optically induced enhancement in molecular mobility during annealing. This suggests that further studies of how solvent exposure, heat, substrate surface properties and particularly light exposure influence the ordering kinetics of TESADT are warranted.

Keywords:

• organic transistor
• crystallisation
• thermal anneal
• triethylsilylethynyl anthradithiophene

Acknowledgements

A.P.M. acknowledges the Australian Research Council (FT0990285) and J.E.A. acknowledges the National Science Foundation (DMR1035257) for support. This work was performed in part using the NSW node of the Australian National Fabrication Facility (ANFF). We thank A.R. Hamilton and P. Meredith for helpful discussions. K. Muhieddine and R.W. Lyttleton contributed equally to this work.