I just fabricate OFET with p3ht spin coating method. I stirred p3ht with chloroform and treat silicon wafer with hmds. When I made it before, the performance was good and its spin coated color is green-blue?? but when I tried to make it again, the color didn't come out well.( it seems more dark color maybe purple??) Can you tell me why? i just control various spin coating speed and temperature but it shows nothing different.
P3HT material is not air stable. If you don't store the material in an inert gas environment, P3HT is degraded. This is why the semiconductor properties changed.
Dear Na Hyeonseo,
Normally the color of the film is mostly related to the thickness of the film. So you have to use the same spin coating conditions (rpm, ramp, duration), and also if there is a large difference in humidity during spin coating ( like summer and winter) the thickness might be different that means you might get a different color. In addition, if you use silica wafer as substrate, the thickness of SiO2 layer will affect the color of the p3ht film ( using 100nm and 300 nm SiO2 thickness gives you different color even though the p3ht thickness is the same). Finally, make sure also you use the same condition when you treat the substrate using hmds since the different conditions will create different contact angles and affect the thickness of p3ht during spin coating. Good luck!
Henok Getachew Girma Thank you for your advice. In fact, I don't change any condition of spin coating before the spin coated fet color is dark and performance is not stable. Have you ever used p3ht dissolved in chloroform? I wonder which color is normal when spin coating is performed. when i read paper, turquoise color is shown which is same as I made first. However, Some papers show the same purple color as the one I'm currently making.
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