Multicomponent semiconducting polymer systems with low crystallization-induced percolation threshold

Abstract

Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species with the excellent mechanical properties of certain commodity polymers. Here we investigate bicomponent blends comprising semicrystalline regioregular poly(3-hexylthiophene) and selected semicrystalline commodity polymers, and show that, owing to a highly favourable, crystallization-induced phase segregation of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor can be reduced to values as low as 3 wt% without any degradation in device performance. This is in stark contrast to blends containing an amorphous insulating polymer, for which significant reduction in electrical performance was reported. Crystalline-crystalline/semiconducting-insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer itself.

The effect of morphology upon mobility: Implications for bulk heterojunction solar cells with nonuniform blend morphology

“…26 Furthermore, blends of P3HT with nonconducting crystalline polymers have been shown to force the P3HT into structures capable of conducting when the concentration of P3HT is only 3 wt %. 27 Whether the present Monte Carlo approach is appropriate depends upon whether the morphologies generated by simulated annealing match the local morphology of the device in question. However, the morphologies used are expected to be accurate for many blends.…”

A Solution‐Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics

“…In order to maintain a good device performance at low content of the conjugated polymer judiciously chosen processing schemes are necessary. Semi‐crystalline matrix polymers such as polyethylenes and isotactic polystyrene (i‐PS) tend to yield superior results provided that the conjugated polymer crystallizes prior to the insulator 5, 13. Notably, bulk‐charge transport can be maintained down to a semiconductor content of only 10 wt%, as observed by Kumar et al using time‐of‐flight photoconductivity measurements 20.…”

“…Blends of an organic semiconductor and insulating polymer have been successfully employed for a range of opto‐electronic devices including field‐effect transistors (FETs)5, 6, 7, 8, 9, 10, 11, 12 and bulk‐heterojunction solar cells,13, 14 as well as applications such as elastic conductors15, 16, 17 and organic thermoelectrics 18, 19. In order to maintain a good device performance at low content of the conjugated polymer judiciously chosen processing schemes are necessary.…”

Route towards huge magnetoresistance in doped polymers

“…It has been shown that blends of poly(3-hexylthiophene) (P3HT) with nonconducting commodity polymers can show excellent conduction even at P3HT weight percentages of only a few percent. 25 A starting point for realizing the case n = 2 could be the copolymerization of monomeric units with strongly electron accepting and electron donating properties. The onset of the optical transition for charge transfer in these polymers marks the energy needed to generate free charge carriers and has been made as low as = 0.5 eV.…”