The Langmuir−Blodgett (LB) and Langmuir− Schaefer techniques facilitate thermodynamic favorability at an air−water interface, at which nanoscale molecular aggregations can be manipulated by micrometer-or millimeter-scale mechanics. The customary use of an aqueous subphase has limitations in the available temperature and spread materials. We present a general strategy to replace the aqueous subphase with an inert, low-vaporpressure liquid, ethylene glycol. As a representative spread material that requires high-temperature processes, a semicrystalline polymeric semiconductor was investigated. We successfully demonstrated that the polymeric semiconductor spreads homogeneously across the entire surface of ethylene glycol heated to 100 °C using an LB trough, and spontaneously forms multilayers. Comprehensive studies such as X-ray diffraction, optical spectroscopy, and charge transport measurements revealed that barrier compression of solid-state polymer thin films during a high-temperature LB process produced uniaxial alignment of the polymer main chain with an averaged dichroic ratio of about 8, by which the electron transport concomitantly became highly anisotropic. The LB method presented in this work could be used to deposit thin films under ultimate environments, e.g., below 0 °C or above 100 °C, minimizing the effects of the vapor pressure of the subphase.

Self-organization in π-conjugated polymers gives rise to a highly ordered lamellar structure, in which inter-chain stacking spontaneously forms two-dimensional conjugated sheets. This multi-layer stacked nature of semicrystalline polymers allows the inclusion of various functional molecules. In particular, redox-triggered ion-intercalation is an ideal system for molecular doping, for which extremely high charge carrier density has been achieved. Here, we conducted a detailed structural analysis and electron density simulation to pinpoint exactly where the guest dopants are located periodically in the void space in a polymer’s lamellae. Our findings are indicative of an intercalation compound of layered polymers and a guest intercalant. We show that a homogeneous cocrystal structure can be realized throughout the host polymer medium, which is proved by the observation of coherent carrier transport. The intercalation cocrystal nature gives the best achievable doping level in semicrystalline polymers and excellent environmental stability. These findings should open up possibilities for tuning the collective dynamics of functional molecules through intercalation phenomena.

Self-organization in π-conjugated polymers gives rise to a highly ordered lamellar structure, in which inter-chain stacking spontaneously forms two-dimensional conjugated sheets. This multi-layer stacked nature of semicrystalline polymers results not only in effective charge transport, but also allows the inclusion of various functional molecules and ions. In particular, redox-triggered ion-intercalation in a polymer's lamellae is an ideal system for molecular doping, for which extremely high charge carrier density, corresponding to one carrier per monomer unit, has been achieved. We conducted a detailed structural analysis and electron density simulation to pinpoint exactly where the guest dopants are located periodically in the restricted void space in a polymer's lamellae. Our findings are indicative of an intercalation compound of layered polymers and a guest intercalant. In addition, we show that a homogeneous cocrystal structure can be realized throughout the host polymer medium, which is proved unambiguously by the observation of coherent carrier transport across microscopic-scale films. Also, the intercalation cocrystal nature gives the best achievable doping level in semicrystalline conjugated polymers and excellent environmental stability. These findings should open up new possibilities for tuning the collective dynamics of functional molecules and ions through intercalation phenomena.