Thin-film transistors
A thin film transistor having a semiconducting layer with improved flexibility and/or mobility is disclosed. The semiconducting layer comprises a semiconducting polymer and insulating polymer. Methods for forming and using such thin-film transistors are also disclosed.
1. A semiconductor composition comprising:
a solvent;
from about 0.1 to about 5 percent by weight of the composition of a semiconducting polymer; and
from about 0.01 to about 2.5 percent by weight of the composition of an insulating polymer;
wherein the composition has a viscosity from about 1.5 centipoise to about 20 centipoise.
2. The composition of claim 1 , wherein the semiconducting polymer is crystalline and the insulating polymer is amorphous.
3. The composition of claim 1 , wherein the composition has a viscosity of from about 2 centipoise to about 12 centipoise.
4. The composition of claim 1 , wherein the semiconductor polymer has a weight average molecular weight of 50,000 or less and the insulating polymer has a weight average molecular weight of 100,000 or greater.
5. The composition of claim 1 , wherein the insulating polymer is polystyrene and the semiconducting polymer has the structure of
wherein R and R′ are independently selected from alkyl or substituted alkyl containing from 1 to about 20 carbon atoms, a heteroatom-comprising group, and halogen; and n is a integer from about 3 to about 50.
6. The composition of claim 1 , wherein the semiconducting polymer has a crystallinity of greater than 50 percent.
7. The composition of claim 1 , wherein the semiconducting polymer has a melting point of 100° C. or higher.
8. The composition of claim 1 , wherein the semiconducting polymer has a melting point of 200° C. or higher.
9. The composition of claim 1 , wherein the semiconducting polymer is selected from the group consisting of polythiophenes, polythiophenes comprising substituted and unsubstituted thienylene groups, polythiophenes comprising optionally substituted thieno[3,2-b]thiophene and/or optionally substituted thieno[2,3-b]thiophene groups, polythiophenes comprising fused-ring aromatic groups selected from benzothiophene, benzodithiophene, and indolocarbazole, and polythiophenes comprising non-thiophene based aromatic groups including phenylene, fluorene, and furan.
10. The composition of claim 1 , wherein the semiconducting polymer is selected from the group consisting of polymers A to D:
wherein R and R′ are independently selected from hydrogen, alkyl or substituted alkyl containing from 1 to about 20 carbon atoms, a heteroatom-comprising group, and halogen; and n is a integer from about 3 to about 200.
11. The composition of claim 1 , wherein the semiconducting polymer is polymer D:
wherein R is independently selected from hydrogen, alkyl or substituted alkyl containing from 1 to about 20 carbon atoms, a heteroatom-comprising group, and halogen; and n is a integer from about 3 to about 200.
12. The composition of claim 1 , wherein the insulating polymer is selected from the group consisting of polystyrene, poly(α-methylstyrene), poly(4-vinyl biphenyl), poly(vinyl cinnamate), and polysiloxane.
13. The composition of claim 1 , wherein the insulating polymer is an amorphous polymer having a weight average molecular weight of at least 2,000.
14. The composition of claim 1 , wherein the insulating polymer has a weight average molecular weight of from about 5,000 to about 1,000,000.