Thermo-mechanical stabilisation of a crystalline organic semiconductor for robust large area electronics

We report the first demonstration of the thermo-mechanical stabilisation of a semi-crystalline organic semiconductor by blending with an insulating polymer binder – an important step towards environmentally-robust solution-processible high performance semi-crystalline organic semi-conductors. In this work, organic thin film transistors (TFTs) were fabricated from 1,4,8,11-tetramethyl-6,13-triethylsilylethynyl pentacene (TMTES-pentacene) either directly or blended with isotactic poly(α-vinyl naphthalene) (iPVN). In measurements over the temperature range 353 K down to 153 K, the TMTES-pentacene devices either failed completely or displayed significantly reduced mobility upon warming to room temperature. On the other hand, TFTs formed from the blend showed little degradation during thermal cycling. Detailed analysis suggested that the saturation mobility was dominated by a parasitic resistance in series with the accumulation channel. We conclude that the resistance is associated with the bulk semiconductor between the source-drain contacts and the channel. Reducing this resistance could lead to significantly improved device performance.