With the aim of enhancing the field-effect mobility by promoting surface-mediated two-dimensional molecular ordering in self-aligned regioregular poly(3-hexylthiophene) (P3HT) we have controlled the intermolecular interaction at the interface between P3HT and the insulator substrate by using self-assembled monolayers (SAMs) functionalized with various groups (–NH2, –OH, and –CH3). We have found that, depending on the properties of the substrate surface, the P3HT nanocrystals adopt two different orientations—parallel and perpendicular to the insulator substrate—which have field-effect mobilities that differ by more than a factor of 4, and that are as high as 0.28 cm2 V–1 s–1. This surprising increase in field-effect mobility arises in particular for the perpendicular orientation of the nanocrystals with respect to the insulator substrate. Further, the perpendicular orientation of P3HT nanocrystals can be explained by the following factors: the unshared electron pairs of the SAM end groups, the π–H interactions between the thienyl-backbone bearing π-systems and the H (hydrogen) atoms of the SAM end groups, and interdigitation between the alkyl chains of P3HT and the alkyl chains of the SAMs.

Enhancement of Field-Effect Mobility by Surface-Mediated Molecular Ordering in Regioregular Polythiophene Thin Film Transistor

Heterogeneous interfaces that are ubiquitous in optoelectronic devices play a key role in the device performance and have led to the prosperity of today’s microelectronics. Interface engineering pr...

Interface Engineering in Organic Field-Effect Transistors: Principles, Applications, and Perspectives

/pdf/transparent-heaters-a-review-umiv831ieu.pdf

Transparent Heaters: A Review

Metal nanowire networks (MNNs) are promising as transparent electrode materials for a diverse range of optoelectronic devices and also work as active materials for electrical heating and electromagnetic interference (EMI) shielding applications. However, the relatively low performance and poor durability of MNNs are limiting the practical application of the resulting devices. Here, we report a controllable approach to enhance the conductivity and the stability of MNNs with their transmittance remaining unchanged, in which reduced graphene oxide conformally wrapped silver nanowire networks (AgNW@rGO networks) are synthesized by selective electrodeposition of GO nanosheets on AgNWs followed by a pulsed laser irradiation treatment. Experimental characterizations and finite-difference time-domain simulations indicate that pulsed laser irradiation at a specific wavelength not only reduces the GO but also welds the AgNWs together through a surface plasmon resonance process. As a result, the AgNW@rGO networks exhibit low sheet resistance of 3.3 Ω/□, average transmittance of 91.1%, and good flexibility. Wrapping with rGO improves the maximum electrical heating temperature of the AgNW network transparent heaters due to the effective suppression of the oxidation and the migration of surface silver atoms. In addition, excellent EMI shielding effectiveness of up to 35.5 dB in the 8.2-12.4 GHz frequency range is obtained as a consequence of the combined effects of dual reflection, conduction loss, and multiple dielectric polarization relaxation processes.

Reduced Graphene Oxide Conformally Wrapped Silver Nanowire Networks for Flexible Transparent Heating and Electromagnetic Interference Shielding

The semiconductor of an organic field-effect transistor is stripped with adhesive tape, yielding an exposed gate dielectric, accessible for various characterization techniques. By using scanning Kelvin probe microscopy we reveal that trapped charges after gate bias stress are located at the gate dielectric and not in the semiconductor. Charging of the gate dielectric is confirmed by the fact that the threshold voltage shift remains, when a pristine organic semiconductor is deposited on the exposed gate dielectric of a stressed and delaminated field-effect transistor.

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Revealing Buried Interfaces to Understand the Origins of Threshold Voltage Shifts in Organic Field-Effect Transistors

Self-assembled monolayers for electrode fabrication and efficient threshold voltage control of organic transistors with amorphous semiconductor layer

Fabrication of silver nanowires (AgNWs) with fine and independent control of both the diameter (from 30 to 120 nm) and length (from 5 to 120 μm) by concomitant addition of co-nucleants and temperature control is demonstrated, and used for the preparation of size standards. Percolating random networks were fabricated using these standards and their optoelectronic properties were measured and compared with regard to the nanowire dimensions. The transparent electrodes appear suitable for various applications and exhibit excellent performances (e.g. 16 ohm sq −1 at 93% transparency), with haze values varying from 1.6 to 26.2%. Besides, in vitro toxicological studies carried out on murine macrophages with the same size standards revealed that AgNWs are weakly toxic (no toxicity observed below 50 μg mL −1 Ag), in particular compared to other silver nanoparticles. Short AgNWs (4 μm) appeared to be slightly more toxic than longer AgNWs (10 and 20 μm). Conversely, long AgNWs (20 μm) induced a more prolonged pro-inflammatory response in murine macrophages. These results contribute, in a safer by design approach, to promoting the use of short AgNWs. The global knowledge dealing with the combination of nanowire dimensions associated with optoelectronic performances and related toxicity should encourage the rational use of AgNWs, and guide the choice of the most adequate AgNW dimensions in an integrated approach.

/pdf/a-toxicology-informed-safer-by-design-approach-for-the-fuo3nscn06.pdf

A toxicology-informed, safer by design approach for the fabrication of transparent electrodes based on silver nanowires

La presente invention se rapporte a un dispositif chauffant (1) comportant : - un substrat de base (11); - une couche electroconductrice (12), dite couche chauffante, portee par le substrat (11), formee d'au moins un reseau percolant de nano-objets comprenant des nanofils metalliques; et - une couche de diffusion thermique (13) a base de nitrure d'aluminium, recouvrant tout ou partie de la couche chauffante (12). Elle concerne egalement un procede de preparation d'un tel dispositif chauffant.

Dispositif chauffant, en particulier semi-transparent

The present disclosure relates to a multi-layer stack which is useful for forming a multi-junction organic photovoltaic cell, said stack including first and second active layers, and an intermediate p-type or n-type layer, inserted between said first and second active layers and in contact with at least one of the first and second active layers, said intermediate layer including a network of electrically conductive nanowires, said stack including an additional layer, inserted between the first active layer and the second active layer and directly in contact with the first active layer or the second active layer, the additional layer being P-type or N-type, separate from the one forming the intermediate layer.

Caroline Celle

Papers

Transparent Heaters: A Review

Self-assembled monolayers for electrode fabrication and efficient threshold voltage control of organic transistors with amorphous semiconductor layer

A toxicology-informed, safer by design approach for the fabrication of transparent electrodes based on silver nanowires

Dispositif chauffant, en particulier semi-transparent

Multi-terminal tandem cells