Poly(3-hexylthiophene-2,5-diyl) (regioregular) is widely used in organic electronics due to its excellent semiconducting properties. It is a key material in the fabrication of organic field-effect transistors (OFETs), where it serves as the active layer, enabling efficient charge transport. This polymer is also integral to organic photovoltaic (OPV) devices, where it acts as a donor material in bulk heterojunction solar cells, helping to convert sunlight into electricity. Additionally, it is employed in organic light-emitting diodes (OLEDs) to enhance device performance and efficiency. Its regioregular structure ensures high crystallinity and improved electrical conductivity, making it a preferred choice for advanced electronic applications.