Material:P3HT

Chemical structure of P3HT.

Poly(3-hexylthiophene) (P3HT) is a polymer with chemical formula (C₁₀H₁₄S)_n. It is a polythiophene with a short alkyl group on each repeat unit. It is noteworthy since it is a seminconducting polymer; it can conduct positive charges (holes). It is a common material for studies of organic electronics (e.g. FETs) and for organic photovoltaics (OPV).

Organization

P3HT typically organizes into a semi-crystalline state, with an idealized unit cell as shown below:

Cartoon of an idealized P3HT unit cell.

• The lamellar stacking has a spacing of ~1.6 nm, giving rise to a peak (100) at q ~0.4 Å⁻¹.
• The aromatic (π-π) stacking has a spacing of ~0.39 nm, giving rise to a peak (010) at q ~1.6 Å⁻¹.
• The spacing along the ring direction is too disordered to give a well-defined 001 peak.

Refer to P3HT orientation for details about the organization of P3HT.

Scattering

On flat substrates, P3HT typically organizes into an edge-on orientation, wherein the lamellar stacking direction is along the film normal (leading to the 100 peak being along q_z), and the aromatic stacking then being in-plane (010 peak along q_r).

Properties

• Density: ~1.33 g/cm³
• Neutron SLD: 0.817×10⁻⁶ Å⁻²

Material	density (g/cm3)	X-ray energy (keV)	X-ray wavelength (Å)	critical angle (°)	qc (Å−1)	SLD (10−6Å−2)
P3HT	1.33	2.0	6.20	0.700	0.0248	12.20
		4.0	3.10	0.352	0.0249	12.33
		8.0	1.55	0.176	0.0249	12.29
		12.0	1.03	0.117	0.0248	12.25
		16.0	0.77	0.088	0.0248	12.24
		24.0	0.52	0.058	0.0248	12.2

See Also

• Wikipedia: polythiophene
• Electron Diffraction and unit-cell: Martin Brinkmann, Christophe Contal, Navaphun Kayunkid, Tatjana Djuric, and Roland Resel Highly Oriented and Nanotextured Films of Regioregular Poly(3-hexylthiophene) Grown by Epitaxy on the Nanostructured Surface of an Aromatic Substrate Macromolecules 2010, 43(18), 7604-7610. doi: 10.1021/ma101313m
• Peter Müller-Buschbaum The Active Layer Morphology of Organic Solar Cells Probed with Grazing Incidence Scattering Techniques Advanced Materials 2014, 26 (46), 7692-7709. doi: 10.1002/adma.201304187