Epidermal electronic systems (EESs) are skin-like electronic systems, which can be used to measure several physiological parameters from the skin. This paper presents materials and a simple, straightforward fabrication process for skin-conformable inkjet-printed temperature sensors. Epidermal temperature sensors are already presented in some studies, but they are mainly fabricated using traditional photolithography processes. These traditional fabrication routes have several processing steps and they create a substantial amount of material waste. Hence utilizing printing processes, the EES may become attractive for disposable systems by decreasing the manufacturing costs and reducing the wasted materials. In this study, the sensors are fabricated with inkjet-printed graphene/PEDOT:PSS ink and the printing is done on top of a skin-conformable polyurethane plaster (adhesive bandage). Sensor characterization was conducted both in inert and ambient atmosphere and the graphene/PEDOT:PSS temperature sensors (thermistors) were able reach higher than 0.06% per degree Celsius sensitivity in an optimal environment exhibiting negative temperature dependence.

A series of electron donor−acceptor (DA) dyads, composed of a porphyrin donor and a fullerene acceptor covalently linked with two molecular chains, were used to fabricate solid molecular films with the Langmuir−Blodgett (LB) technique. By means of the LB technique, the DA molecules can be oriented perpendicular to the plane of the substrate. In DHD6ee and its zinc derivative hydrophilic groups are attached to the phenyl moieties in the porphyrin end of the molecule; while in the other three dyads, TBD6a, TBD6hp, and TBD4hp, the hydrophilic groups are in the fullerene end of the molecule. This makes it possible to alternate the orientation of the molecules in two opposite directions with respect to the air−water interface and to fabricate molecular assemblies in which the direction of the primary photoinduced vectorial electron transfer can be controlled both by the deposition direction of the LB monolayer and by the selection of the used DA molecule. This was proved by the time-resolved Maxwell displacement charge measurements. The spectroscopic properties of the DA films were studied with the steady-state absorption and fluorescence methods. In addition, the time correlated single photon counting technique was used to determine the fluorescence properties of the dyad films.

Two porphyrin-fullerene dyads were synthesized to form self-assembled monolayers (SAMs) on indium-tin oxide (ITO) electrode, with either ITO-porphyrin-fullerene or ITO-fullerene-porphyrin orientations. The dyads contain two linkers for connecting the porphyrin and fullerene moieties and enforcing them essentially to similar geometries of the donor-acceptor pair, and two linkers to ensure the attachment of the dyads to the ITO surface with two desired opposite orientations. The transient photovoltage responses (Maxwell displacement charge) were measured for the dyad films covered by insulating LB films, thus ensuring that the dyads interact only with the ITO electrode. The direction of the electron transfer was from the photoexcited dyad to ITO independent of the dyad orientation. The response amplitude for the ITO-fullerene-porphyrin structure, where the primary intramolecular electron-transfer direction coincides with the direction of the final electron transfer from the dyad to ITO, was 25 times stronger than that for the opposite ITO-porphyrin-fullerene orientation of the dyad. Static photocurrent measurements in a liquid electrochemical cell, however, show only a minor orientation effect, indicating that the photocurrent generation is controlled by the processes at the SAM-liquid interface.

The ongoing revolution of touch‐based user interfaces sets new requirements for touch panel technologies, including the need to operate in a wide range of environments. Such touch panels need to endure moisture and sunlight. Moreover, they often need to be curved or flexible. Thus, there is a need for new technologies suitable, for example, for home appliances used in the kitchen or the bathroom, automotive applications, and e‐paper. In this work, the development of transparent and flexible touch panels for moist environments is reported. A piezoelectric polymer, poly(vinylidene difluoride) (PVDF), is used as a functional substrate material. Transparent electrodes are fabricated on both sides of a PVDF film using a graphene‐based ink and spray coating. The excellent performance of the touch panels is demonstrated in moist and underwater conditions. Also, the transparent device shows very small pyroelectric response to radiative heating in comparison to a non‐transparent device. Solution processable electrode materials in combination with functional substrates allow the low‐cost and high‐throughput manufacturing of touch panels using printing technologies.

Layers of poly(3-hexylthiophene), PHT, phenyl vinyl thiophene, PVT3, poly(p-phenylene-2,3′-bis(3,2′diphenyl)-quinoxaline-7-7′-diyl), PPQ, and covalently linked porphyrin-fullerene donor-acceptor dyad, P-F, were deposited as various multilayer films, which then were used to study photoinduced electron transfer and photocurrent generation. The aim of the research was to clarify functioning of different energy and electron donating and accepting layers in charge transfer processes, which were initially created in a film consisting of parallel P-F molecules. The reactions were studied by means of time-correlated and steady-state fluorescence, time-resolved photovoltage, and electrochemical photocurrent measurements. The longest-lived charge-separated state and the highest efficiency of photocurrent generation were obtained for the multilayer structure of PHT|PVT3|porphyrin-fullerene. Porphyrin-fullerene dyads deposited parallel as the Langmuir -Blodgett film transfer electrons from porphyrin to fullerene yielding radical cation and anion moieties, respectively. The dyad on a PHT layer induces electron donation from PHT to the porphyrin cation. When PVT3 is deposited between the PHT and the P-F layers, it promotes both energy and electron transfer to the porphyrin moiety of the dyad, retards the recombination of the primary charge-separated state, and thus increases the photocurrent generation. PPQ was used as an electron acceptor from the fullerene radical anion, causing an increased lifetime of the charge separation.