Polaron formation via doping process in an organic semiconductor polymer based on thiophene-phenylene

• Published in: European polymer journal 2024-11, Vol.220, p.113485, Article 113485
• Main Authors: Silva, M.D.R., de Fátima Curcino da Silva, Silésia, Jarrosson, T., Lère-Porte, J.-P., Serein-Spirau, Françoise, Nobuyasu, Roberto S., Dalkiranis, Gustavo G., Zanatta, Bruno S., Lucia Nogueira, Sandra, Foschini, M., Silva, R.A., Marletta, A.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Doping; Gamma radiation; Organic semiconductor; Polymer chain; Solvent; Thiophene-phenylene
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2024.113485

[Display omitted] •An enlightening study upon polarons and bipolarons, formation and its properties.•Polymer in solution display doped properties when exposed to H+ ions.•Proximal chemical environment promoting doping via a reversible alteration on the thiophene group.•The gamma radiation serves as a tool for the doping process. Phenylene and thiophene confer a set of advantageous properties to the polymer.•The gamma radiation interaction with polymer is solvent dependent. In this research, we synthesized and analyzed the polymer 5-(5-(10-chlorodecyloxy)-2-methoxy-4-(5-methylthiophen-2-yl)phenyl)-5′-(2-(2-ethylhexyloxy)-5-methoxy-4-(5-methylthiophen-2-yl)phenyl)-2,2′-bithiophene (PTBT46). The polymer was dissolved in chloroform and subjected to gamma radiation doses ranging from 0 to 100 Gy (gray). We observed that PTBT46 can be doped with H+ions, as indicated by visible color changes, optical measurements, and a tenfold increase in conductivity. When analyzing PTBT46 in solution using THF (tetrahydrofuran) and chloroform, we found a notable solvent dependence. In chloroform, new absorption bands appeared at approximately 680 nm and 2630 nm after radiation doses of 25 to 100 Gy, which were not present in THF. These bands are attributed to polarons and bipolarons resulting from the doping process. Additionally, we observed a spectral “blue shift” with increasing H+concentration due to changes in molecular conjugation, without degradation of the polymer chain. This shift, confirmed by Fourier-transform infrared (FTIR) spectroscopy, is reversible and suggests potential applications in optoelectronic devices and advanced radiation sensors.