Controlling Polymorphism in Poly(3‐Hexylthiophene) through Addition of Ferrocene for Enhanced Charge Mobilities in Thin‐Film Transistors |
| |
| Authors: | Brandon H. Smith Michael B. Clark Jr. Hao Kuang Christopher Grieco Alec V. Larsen Chenhui Zhu Cheng Wang Alexander Hexemer John B. Asbury Michael J. Janik Enrique D. Gomez |
| |
| Affiliation: | 1. Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, USA;2. The Dow Chemical Company, Collegeville, Pennsylvania, USA;3. Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA;4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA |
| |
| Abstract: | Crystalline organic molecules often exhibit the ability to assemble into multiple crystal structures depending on the processing conditions. Exploiting this polymorphism to optimize molecular orbital overlap between adjacent molecules in the unit lattice is an effective method for improving charge transport within the material. In this study, grazing incident X‐ray diffraction was employed to demonstrate the formation of tighter π‐π stacking poly(3‐hexylthiophene‐2,5‐diyl) polymorphs in films spin coated from ferrocene‐containing solutions. As a result, the addition of ferrocene to casting solutions yields thin‐film transistors which exhibit approximately three times higher source‐drain currents and charge mobilities than neat polymer devices. Nevertheless, XPS depth profiling and NMR analyses of the active layer reveal that all ferrocene is removed during the spin coating process, which may be an essential factor to achieve high mobilities. Such insights gleaned from ferrocene/poly(3‐hexylthiophene‐2,5‐diyl) mixtures can serve as a template for selection and optimization of other small molecule/polymer systems with greater baseline charge mobilities. |
| |
| Keywords: | organic field‐effect transistors charge transport conjugated polymers metallocenes time‐resolved infrared spectroscopy |
|
|
