Poly(3-hexylthiophene) Film Structure Regulation And Control And In Situ Detection

Poly (3-hexyl thiophene)(P3HT) is an organic polymer semiconductor which is successful synthesized ineighties of the last century, it has a good solubility in the conventional solution, lightweight flexible, low cost and excellent features, and it can simply spin coating or inkjet printing and other methods to making the flexible film on substrate. In this paper, P3HT as the research object, using in situ infrared technology in an inert atmosphere we researchedits molecular structure and dynamics of crystalline transition, but also we analyzed the stability of P3HT at different oxygen content atmosphere.Through the P3HT film in an inert atmosphere at atmospheric pressure in situ IR experiments, we found that P3HT film is mainly characterized by two crystalline states:plastic crystal and amorphous. The different peak position(～820cm-1:outside Cβ-H plane deformation vibration peaks) can be characterized P3HT films with different molecular states. By analyzing the in situ infrared spectroscopy, we found the transformation rule of P3HT molecular structure during heating:The rigid backbone of thiophene is almost unaffectedat110℃before; When the temperature is higher than110℃, the chain began distorted, plastic crystal slowly transformingto amorphous state; when the temperature reaches the melting temperature, the plastic quickly transformed into crystalline amorphous.We use high-pressure inert atmosphere situ FTIR experiments to study the effects of the atmosphere pressure in the heating process of P3HT molecular structure. We found that:in a high pressure atmosphere, the transition temperature which the molecular backbone transform to the disordered arrangement with increasing temperature raised, namely gas pressure can inhibit the transition of P3HT molecules from the π-π-conjugated system of the larger to in non-crystalline plastic crystalline.In the stability of P3HT, the in situ infrared experiment with different oxygen-containing atmosphereand the XPS experimental data showed that:P3HT oxidation is divided into two parts:On the one hand, the oxidation of molecular alkyl side chains; on the other hand,the oxidation of sulfur in molecular thiophene ring main chain.We also found that in the atmosphere of different oxygen concentration, oxidation occurs at different temperatures. With the increase of oxygen concentration, the oxidation temperature decreases. In the low oxygen concentration (1%02, normal pressure) atmosphere, P3HT is partially oxidized, and the oxidized portion located in a side chain attached to carbon of the thiophene ring, and the backbone of thiophene ring is not oxidized. Through the transit time method(TOF),we found that the mobility ofpartially oxidized P3HT improved by about20%.