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- Riera-Galindo, Sergi, et al.
(author)
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Impact of Singly Occupied Molecular Orbital Energy on the n-Doping Efficiency of Benzimidazole Derivatives
- 2019
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In: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:41, s. 37981-37990
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Journal article (peer-reviewed)abstract
- We investigated the impact of singly occupied molecular orbital (SOMO) energy on the n-doping efficiency of benzimidazole derivatives. By designing and synthesizing a series of new air-stable benzimidazole-based dopants with different SOMO energy levels, we demonstrated that an increase of the dopant SOMO energy by only similar to 0.3 eV enhances the electrical conductivity of a benchmark electron-transporting naphthalenediimide-bithiophene polymer by more than 1 order of magnitude. By combining electrical, X-ray diffraction, and electron paramagnetic resonance measurements with density functional theory calculations and analytical transport simulations, we quantitatively characterized the conductivity, Seebeck coefficient, spin density, and crystallinity of the doped polymer as a function of the dopant SOMO energy. Our findings strongly indicate that charge and energy transport are dominated by the (relative) position of the SOMO level, whereas morphological differences appear to play a lesser role. These results set molecular-design guidelines for next-generation n-type dopants.
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2. |
- Riera-Galindo, Sergi, et al.
(author)
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Organic Semiconductor/Polymer Blend Films for Organic Field-Effect Transistors
- 2019
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In: Advanced Materials Technologies. - : WILEY. - 2365-709X. ; 4:9
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Research review (peer-reviewed)abstract
- The development of low-cost printed organic electronics entails the processing of active organic semiconductors (OSCs) through solution-based techniques. However, the preparation of large-area uniform and reproducible films based on OSC inks can be very challenging due to the low viscosity of their solutions, which causes dewetting problems, the low stability of OSC polymer solutions, or the difficulty in achieving appropriate crystal order. To circumvent this, a promising route is the use of blends of OSCs and insulating binding polymers. This approach typically gives rise to films with an enhanced crystallinity and organic field-effect transistors (OFETs) with significantly improved device performance. Recent progress in the fabrication of OFETs based on OSC/binding polymer inks is reviewed, highlighting the main morphological and structural features that play a major role in determining the final electrical properties and some future perspectives. Undoubtedly, the use of these types of blends results in more reliable and reproducible devices that can be fabricated on large areas and at low cost and, thus, this methodology brings great expectations for the implementation of OSCs in real-world applications.
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