Design,Fabrication,and Performance Investigation Of Organic Field-Effect Transistors Based On N-type Organic Semiconductor Naphthalene Diimides Fused With Sulfur Heterocycles

Organic semiconductors have attracted great attention due to their great prospect in low-cost, light-weight and flexible devices. Nevertheless, there are still problems to be solved in organic electronics. For organic field effect transistors(OFETs), most solution processing techniques depend on chlorinated solvents. Chlorinated solvents may cause health hazard, environmental risk and add cost to waste recovery systems. So processing from environmentally benign solvents offers an alternative and more amenable way for industrial commercialization at a lower capital and environmental cost. In addition, the contact resistance between metal electrode and the organic semiconductor greatly affects carrier injection. Changing the work function of metal electrode could improve device performance by reducing energy barrier. Herein, different non-chlorinated solvents are used to process n-type semiconductor naphthalene diimides fused with sulfur heterocycles(NDI3HU-DTYM2). Moreover, the influence of different electrode and self-assembled monolayer on gold surface on device performance were investigated. The main contents are outlined below. 1. Two processing method, spin-coating and drop-casting, are used to fabricate n-type OFETs based on NDI3HU-DTYM2 in environmentally benign solvents, both methods could achieve electron mobility over 1 cm2V-1s-1 in ambient condition. The influence of high boiling point solvent as an additive of processing solvent are investigated. 2. A series of OFETs based on NDI3HU-DTYM2 are fabricated with different electrode Au, Ag and Cr-Au, but the device performance doesn’t improve upon the seemingly reduced injection barrier. Different electrode modification layer pentafluorobenzenethiol(PFBT) and 1,1-dicyanoethylene-2,2-dithiolate(DCDT) are used to change the work function of gold electrode. For Bottom Gate Bottom Contact(BGBC) device modified with DCDT, device performance(mobilty) is twice as much as those with no modification on Au.