Controlling polarity of organic bulk heterojunction field-effect transistors via solvent additives.

The effect of additives such as 1,8-diiodooctane (DIO) and 1-chloronaphthalene (CN) on the electronic structures, charge transport and phase separation of small-molecule-based bulk heterojunction (BHJ) films was investigated. Charge transport properties of the BHJ layers significantly changed via the introduction of additives, even though the molecular energy levels remained unchanged. X-ray photoelectron microscopy (XPM) images show the distribution of each phase of the blend films upon the use of additives. The CN additive, in particular, results in a well-percolated network through the active layer.