Bectron Varnish

Such a transistor device can drive a drain-source current of -17.1 nA at Vos -40 V and Vos 80 V (ML = 22.4). The output eharaeteristic did not show good behaviour, possibly due to a large charge earrier barrier, caused by the differenee of the work function of the titanium (4.3 eV [30]) and the HOMO (highest oeeupied molecule orbital) of the pentaeene film (4.8 eV [31]) that are not well adapted. Au, Pd or Pt would fit mueh better [32]. 

Furthermore, there could have been negative effeets on the OFETs by the deposition of the metal layers. In [33] a diffusion of metal atoms into the or-ganie semieonduetor or a formation of a mixing layer on the rough surface of the pentaeene film was reported. This can excite an additional shift of the Fermi level that need not shift in direction to improve the charge carrier injection. 

Moreover, thermal effects could have an impact on the organic semiconductor due to a temperature of more than 80 °C during the deposition process of titanium as a eonsequence of thermal radiation. It could not be ruled out that this proeess step entails a premature degradation. 

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