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.

A comprehensive understanding of the roles of various nanointerfaces in thermal transport is of critical significance but remains challenging. A two-dimensional van der Waals (vdW) heterostructure with tunable interface lattice mismatch provides an ideal platform to explore the correlation between thermal properties and nanointerfaces and achieve controllable tuning of heat flow. Here, we demonstrate that interfacial engineering is an efficient strategy to tune thermal transport via systematic investigation of the thermal conductance (G) across a series of large-area four-layer stacked vdW materials using an improved polyethylene glycol-assisted time-domain thermoreflectance method. Owing to its rich interfacial mismatch and weak interfacial coupling, the vertically stacked MoSe 2 -MoS 2 -MoSe 2 -MoS 2 heterostructure demonstrates the lowest G of 1.5 MW m −2 K −1 among all vdW structures. A roadmap to tune G via homointerfacial mismatch, interfacial coupling, and heterointerfacial mismatch is further demonstrated for thermal tuning. Our work reveals the roles of various interfacial effects on heat flow and highlights the importance of the interfacial mismatch and coupling effects in thermal transport. The design principle is also promising for application in other areas, such as the electrical tuning of energy storage and conversion and the thermoelectricity tuning of thermoelectronics.

Crystalline semiconducting polymers can be chemically doped with molecular dopants via integer charge transfer to highly conductive states, where charge carriers in high-mobility, semicrystalline polymers undergo band-like transport. Although coherent, band-like transport characteristics are indispensable for further improvement of conductivity, the correlation between band-like transport and crystallinity in doped conjugated polymers has not been comprehensively studied. Here, we investigate the role of crystallinity in molecular-doped thiophene-based semiconducting regioisomers. The doping efficiency and band-like transport were examined using X-ray diffraction and magnetotransport measurements, which revealed clear differences between regioisomers due to the differences of their polymer packing structures and crystallinity.

Polymorphic transition from the 1D ribbon to the 2D carpet superstructure of squaric acid molecules on Au(111) was achieved through a thermally activated process. Our combined STM and DFT study revealed that the molecular arrangements in 1D and 2D superstructures are determined by the stability of their conformational isomers and assembled structures, respectively.

Understanding the relationships between the thermal conductivity and carrier density in thin films is of great importance for the thermal management of flexible thin film electronics. Here, we report a robust measurement technique to tune the carrier density in thin films and to evaluate their cross-plane thermal conductivities simultaneously. We employed the time-domain thermoreflectance method using an Au transducer and evaluated the thin film thermal conductivity in situ using electrolyte gating with an ionic gel. The robust measurement technique proposed in this study elucidated the relationships among the above-mentioned parameters in semiconducting single-walled carbon nanotubes.

Crystal structures of eight derivatives of bis(diphenylglyoximato)–nickel(II), bearing four alkoxy chains of different lengths, were determined by single-crystal X-ray crystallography. Sequential transition of packing structures by chain elongation was observed. The packing structures were typically one-dimensional columnar structure comprising metal wires, herringbone structures, quasi-layered structures and layered structures having an interdigitation of alkyl moieties in the alkoxy chains. Each structural characteristic depends on odd–even effect and alkoxy chain interactions. Additionally, the gauche conformation of the alkoxy chains contributes to filling the empty spaces of the structures, placing out of the molecular plane packing, and forming a clip structure of the alkoxy chains.

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The presence of hopping carriers and grain boundaries can sometimes lead to anomalous carrier types and density overestimation in Hall-effect measurements. Previous Hall-effect studies on carbon nanotube films reported unreasonably large carrier densities without independent assessments of the carrier types and densities. Here, we have systematically investigated the validity of Hall-effect results for a series of metallic, semiconducting, and metal–semiconductor-mixed single-wall carbon nanotube films. With carrier densities controlled through applied gate voltages, we were able to observe the Hall effect both in the n- and p-type regions, detecting opposite signs in the Hall coefficient. By comparing the obtained carrier types and densities against values derived from simultaneous field-effect-transistor measurements, we found that, while the Hall carrier types were always correct, the Hall carrier densities were overestimated by up to four orders of magnitude. This significant overestimation indicates that thin films of one-dimensional SWCNTs are quite different from conventional hopping transport systems.