Design And Synthesis Of Azulene-based Organic Semiconductors

In recent years, organic field-effect transistors(OFETs) have achieved considerable attention for their solution-processability and being able to fabricate large-area flexible devices. In OFETs, organic semiconductors play the most important role in determining their charge transport properties by tunning molecules’ frontier orbital energy and packing morphology. We constructed a series of newly-designed D-A-D molecules to have successfully tuned their frontier orbital energy by introducing various electron-withdrwing and electron-donating groups. The thesis primarily contains the following several parts:1. A series of D-A-D structures adopting thieno[3,4-c]pyrrole-4,6-dione(TPD) as acceptor and naphthalene, benzo[b]thiophene(BT), azulene respectively as donor have been designed and synthesized. Their optical and electronic properties have been characterized. We observed that the azulene-based molecules have narrower band gaps and delocalized LUMO distribution which is favorable for electron transport. Naphthalene-, BT-based compounds have high thermal stabilities. And the charge transport properties of the naphthalene-based compound have been preliminarily explored. We found that it showed preferable hole mobility.2. We have synthesized the terthiophene-based anhydrides with low-cost materials and novel synthesis routes. And the azulene-based intermediate products have been synthezied applying optimized procedure and condition. Their optical properties and theoretical calculation indicated that the formation of anhydrides resulted in smaller band gaps, while sulfonic acid group led to larger band gaps probably due to too strong electron-withdrawing ability; the optical properties of azulene can be affected by substituting groups; carbony groups led to lower frontier obital energies effectively. These works provide important prerequisite for the synthesis of TPD-based compounds and azulene derivatives.