Fabrication Of Polymer Field Effect Tran- Sistors And Investigation Of Their Perfor- Mances

Compared to inorganic field-effect transistors, OFETs offer several advantages, such as low cost, solution processability, mechanical flexibil-ity, and chemical versatility. But the mobility and stability of OFETs are still relatively low, so they cannot be completely used for industrial pro-duction. In this dissertation, we focused on material selection and optimi-zation of the device in order to improve the performance of OFETs.1. We prepared a series of OFETs based on P(NDT3-BT), P(NDT3-BO), P(NDF3-BT), and P(NDF3-BO). We systematically investigated their electrical performance to analysis how the sulfur and oxygen atoms in the bandbond impacted OFETs performance and characterized film morphology of these polymers. It was found that, compared with P(NDF3-BT)/P(NDF3-BO), P(NDT3-BT)/P(NDT3-BO) showed smaller lamellar distance, which results in better hole mobilities.2. The donor cell is Naphthdifuran and the acceptor cells are DPP and IID in PNDF3DPP-C24 and PNDF3IID-C24 conjugated polymers, respectively. And we prepared the bottom gate/bottom contact OFETs based on PNDF3DPP-C24 and PNDF3IID-C24. The OFETs with W/L= 1400/5 showed the highest saturated hole mobilities after annealing optimization at 120℃. The highest saturated mobilities of PNDF3DPP-C24 and PNDF3IID-C24 were 5.31 cm2 V-1 s-1 and 3.35 cm2 V-1 s-1,re-spectively. Film morphology of these polymers were characterized by AFM and GIXRD in order to explain the reasons why the OFETs based on PNDF3DPP-C24 and PNDF3IID-C24 exhibited high performance.3. We investigated a conjugated PNDTP-DPP containing alkyl-phenyl substituted naphthodithiophene. PNDTP-DPP exhibited good so- lubility. We prepared the polymer film by solution method and con-structed the OFET devices. Intermolecular interactions was strong and π-π stacking distance was-3.7 A in the film, which made the hole mobil-ity of the OFETs up to 0.86 cm2 V-1 s-1. The results demonstrated that 2-D molecular configuration is benefical to decrease of interchain distances, therefore to improvement of the hole mobility of the polymer.