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Item type:Publication, Access status: with files , Sequentially processed P3HT/CN6-CP•−NBu4+ films: interfacial or bulk doping?(Wiley-VCH, 2020-04-13); ; ; ; Derivatives of the hexacyano-[3]-radialene anion radical (CN6-CP•−) emerge as a promising new family of p-dopants having a doping strength comparable to that of archetypical dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ). Here, mixed solution (MxS) and sequential processing (SqP) doping methods are compared by using a model semiconductor poly(3-hexylthiophene) (P3HT) and the dopant CN6-CP•−NBu4+ (NBu4+ = tetrabutylammonium). MxS films show a moderate yet thickness-independent conductivity of ≈0.1 S cm−1. For the SqP case, the highest conductivity value of ≈6 S cm−1 is achieved for the thinnest (1.5–3 nm) films whereas conductivity drops two orders of magnitudes for 100 times thicker films. These results are explained in terms of an interfacial doping mechanism realized in the SqP films, where only layers close to the P3HT/dopant interface are doped efficiently, whereas internal P3HT layers remain essentially undoped. This structure is in agreement with transmission electron microscopy, atomic force microscopy, and Kelvin probe force microscopy results. The temperature-dependent conductivity measurements reveal a lower activation energy for charge carriers in SqP samples than in MxS films (79 meV vs 110 meV), which could be a reason for their superior conductivity.Publicationtype: Journal ArticleScopus© Citations 7 26 59 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Layer-by-layer assembly enabled by the anionic p-dopant CN6-CP•-K+: a route to achieve interfacial doping of organic semiconductorsHighly efficient 2D (interfacial) doping of organic semiconductors, poly(3-hexylthiophene) (P3HT) and TIPS-pentacene, was achieved by a polyelectrolyte-supported layer-by-layer assembly of the dual-mode functional dopant CN6-CP•-K+, having an anionic group for its fixation onto oppositely charged surfaces/molecules as well as electron-deficient groups providing its p-doping ability. Polyelectrolyte-supported dopant layers were used to generate conductive channels at the bottom or at the top of semiconducting films. Unlike to the case of sequentially processed P3HT films doped by F4TCNQ (Moulé, J. Chem. Mater. 2015, 27, 5765; Koech, P. K. J. Mater. Chem. C 2013, 1, 1876; Schwartz, B. J. J. Phys. Chem. Lett. 2015, 6, 4786), the use of more polar CN6-CP•-K+ dopant and ultrathin polycation separation interlayer enables predominantly interfacial kind of doping placement with no or minimal intercalation of the dopant into the semiconductor bulk. The layered structure of the doped film was proved by transmission electron microscopy of the cross-section and it agrees well with other data obtained in this work. The interfacial doping enabled an impressive conductivity of 13 S/cm even for ultrathin P3HT films. We propose to explain the superior efficiency of the interfacial doping compared to the bulk doping in terms of unperturbed morphology of the semiconductor and high mobility of charge carriers, which are spatially separated from the dopant phase.Publicationtype: Journal ArticleScopus© Citations 6 23