Effect of side groups on the vacuum thermal evaporation of polythiophenes for organic electronics

• Published in: Organic electronics Vol. 13; no. 4; pp. 687 - 696
• Main Authors: Kovacik, Peter, Willis, Shawn M., Matichak, Jonathan D., Assender, Hazel E., Watt, Andrew A.R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2012; Elsevier
• Subjects: Applied sciences; Compound structure devices; Conjugated polymers; Electrical engineering. Electrical power engineering; Electronics; Energy; Exact sciences and technology; Materials; Natural energy; Optoelectronic devices; Organic solar cells; Photovoltaic conversion; Poly(3-hexylthiophene); Polythiophene; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solar cells. Photoelectrochemical cells; Solar energy; Thin films; Vacuum thermal evaporation; Thin films; Poly(3-hexylthiophene); Conjugated polymers; Polythiophene; Organic solar cells; Vacuum thermal evaporation; Performance evaluation; Atomic force microscopy; Transport properties; Charge transport; Thin film; Conjugated polymer; Charge collection; Packing; Thiophene derivative polymer; Topography; Optoelectronic device; Organic electronics; Heterojunction; Electronic properties; Hole mobility; Polymer films; Solar cell; Fullerenes; Thiophene polymer; Vacuum deposition; Planar technology
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2012.01.005

[Display omitted] ► Vacuum evaporation of polymers with (P3HT) and without side groups (PTh) is reported. ► Polymer side groups influence structural and electronic properties of the films. ► Molecular order and charge transport in PTh are significantly better than in P3HT. ► High PTh hole mobilities (10−4cm2/Vs) and PTh/C60 device efficiencies are achieved. ► Vacuum thermal evaporation is suitable for the deposition of low solubility polymers. The vacuum thermal evaporation of poly(3-hexylthiophene) (P3HT) and poly(thiophene) (PTh) conductive polymers with and without side groups is reported. The role of side groups in relation to structural and electronic properties is examined. FT-IR and GPC analysis is used to study the effect deposition has on conjugation of the polymer. Topography and grain structure of the polymer films are studied using MicroXAM, AFM and TEM. XRD and TEM data reveal enhanced molecular packing and crystallinity of PTh. This results in significantly improved charge transport properties with relatively high hole mobilities (10−4cm2/Vs). Evaluation of PTh and P3HT electronic properties is performed on simple geometry planar C60 heterojunction solar cells. PTh/C60 devices exhibit almost a 70% increase in efficiency as compared to P3HT/C60 devices, demonstrating enhanced charge collection in PTh films through improved molecular order.