A Thiadiazole-capped Nanoribbon with 18 Linearly-Fused Rings

Polycyclic aromatic hydrocarbons that extend over 2 nm in one dimension are seen as monodisperse graphene nanoribbons, which have attracted significant attention for a broad range of applications in organic electronics and photonics. Herein we report the synthesis of a stable bisthiadiazole-capped pyrene-containing nanoribbon with 18 linearly fused rings (NR-18-TD). Thanks to the presence of alternating tert-butyl and tri-iso-butylsilyl groups, NR-18-TD is highly soluble in organic solvents and therefore its structure and fundamental optoelectronic, redox and electrical properties could be unambiguously established. This work illustrates that NR-18-TD is a promising soluble NR-based n-type semiconductor for applications in organic electronics.The authors are grateful to the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country (Grupo de Investigación GIU17/054 and SGIker), Gobierno de España (Ministerio de Economía y Competitividad CTQ2016-77970-R and CTQ2015-71936-REDT), Gobierno Vasco (BERC program), CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), Diputación Foral de Guipúzcoa (OF215/2016(ES)) and the FP7 framework program of the European Union (Marie Curie Career Integration Grant No. 618247 (NIRVANA)). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 664878. This project has also received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 722951

Monodisperse N‐Doped Graphene Nanoribbons Reaching 7.7 Nanometers in Length

The properties of graphene nanoribbons are highly dependent on structural variables such as width, length, edge structure, and heteroatom doping. Therefore, atomic precision over all these variables is necessary for establishing their fundamental properties and exploring their potential applications. An iterative approach is presented that assembles a small and carefully designed molecular building block into monodisperse N-doped graphene nanoribbons with different lengths. To showcase this approach, the synthesis and characterisation of a series of nanoribbons constituted of 10, 20 and 30 conjugated linearly-fused rings (2.9, 5.3, and 7.7 nm in length, respectively) is presented.We are grateful to the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country (SGIker), the Deutsche Forschungsgemeinschaft (MA 5215/4-1), Gobierno de Espana (Ministerio de Economia y Competitividad CTQ2016-77970-R and CTQ2015-71936-REDT), Gobierno Vasco (BERC program and PC2015-1-01(0637)), Diputacion Foral de Guipuzcoa (OF215/2016(ES)), CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), ON2 (NORTE-07-0162-FEDER-000086), and the FP7 framework program of the European Union (ERA Chemistry, Marie Curie Career Integration Grant No. 618247 (NIRVANA)). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 664878. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 722951)

BODIPY star-shaped molecules as solid state colour converters for visible light communications

We thank EPSRC for financial support from the UP-VLC Programme Grant (EP/K00042X/1). I.D.W.S. and P.J.S. are Royal Society Wolfson Research Merit Award holders. The research data supporting this publication can be accessed at http://dx.doi.org/10.17630/20163d03-6cc2-43b6-915c-d271f5220454.In this paper we study a family of solid-state, organic semiconductors for visible light communications. The star-shaped molecules have a boron-dipyrromethene (BODIPY) core with a range of side arm lengths which control the photophysical properties. The molecules emit red light with photoluminescence quantum yields ranging from 22 - 56 %. Thin films of the most promising BODIPY molecules were used as a red colour converter for visible light communications. The film enabled colour conversion with a modulation bandwidth of 73 MHz, which is 16 times higher than of a typical phosphor used in LED lighting systems. A data rate of 370 Mbit/s was demonstrated using On-Off keying modulation in a free space link with a distance of ~15 cm.PostprintPublisher PDFPeer reviewe

BODIPY-based conjugated polymers for broadband light sensing and harvesting applications

The synthesis of novel low band-gap polymers has significantly improved light sensing and harvesting in polymer-fullerene devices. Here the synthesis of two low band-gap polymers based on the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene core (BODIPY), and either bis(3,4-ethylenedioxythiophene) (bis-EDOT) or its all-sulfur analogue bis(3,4-ethylenedithiathiophene) (bis-EDTT) are described. The polymers demonstrate ambipolar charge transport and are shown to be suitable for broadband light sensing and solar energy harvesting in solution-processable polymer-fullerene devices

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

Star-shaped conjugated systems with varying oligofluorene arm length and substitution patterns of the central BODIPY core have been synthesised, leading to two families of compounds, T-B1–T-B4 and Y-B1–Y-B4, with T- and Y-shaped motifs, respectively. Thermal stability, cyclic voltammetry, absorption and photoluminescence spectroscopy of each member of these two families were studied in order to determine their suitability as emissive materials in photonic applications

Depositing Molecular Graphene Nanoribbons on Ag(111) by Electrospray Controlled Ion Beam Deposition: Self-Assembly and On-Surface Transformations

The chemical processing of low-dimensional carbon nanostructures is crucial for their integration in future devices. Here we apply a new methodology in atomically precise engineering by combining multistep solution synthesis of N-doped molecular graphene nanoribbons (GNRs) with mass-selected ultra-high vacuum electrospray controlled ion beam deposition on surfaces and real-space visualisation by scanning tunnelling microscopy. We demonstrate how this method yields solely a controllable amount of single, otherwise unsublimable, GNRs of 2.9 nm length on a planar Ag(111) surface. This methodology allows for further processing by employing on-surface synthesis protocols and exploiting the reactivity of the substrate. Following multiple chemical transformations, the GNRs provide reactive building blocks to form extended, metal-organic coordination polymers.This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreements No. 946223 and No. 899895. Financial support was provided by the German Research Foundation (DFG) through the TUM International Graduate School of Science and Engineering (IGSSE), Excellence Cluster e-conversion, and the priority programme 1928 COORNETs, the China Scholarship Council (CSC) and the European Research Council (ERC) (no. 722951). This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 722951). This work was carried out with support from the Basque Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country, Gobierno Vasco (BERC programme). Technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF) is acknowledged. Open Access funding enabled and organized by Projekt DEAL

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

Star-shaped conjugated systems with varying oligofluorene arm length and substitution patterns of the central BODIPY core have been synthesised, leading to two families of compounds, T-B1-T-B4 and Y-B1-Y-B4, with T- and Y-shaped motifs, respectively. Thermal stability, cyclic voltammetry, absorption and photoluminescence spectroscopy of each member of these two families were studied in order to determine their suitability as emissive materials in photonic applications

An air-stable DPP-thieno-TTF copolymer for single-material solar cell devices and field effect transistors

Following an approach developed in our group to incorporate tetrathiafulvalene (TTF) units into conjugated polymeric systems, we have studied a low band gap polymer incorporating TTF as a donor component. This polymer is based on a fused thieno-TTF unit that enables the direct incorporation of the TTF unit into the polymer, and a second comonomer based on the diketopyrrolopyrrole (DPP) molecule. These units represent a donor–acceptor copolymer system, p(DPP-TTF), showing strong absorption in the UV–visible region of the spectrum. An optimized p(DPP-TTF) polymer organic field effect transistor and a single material organic solar cell device showed excellent performance with a hole mobility of up to 5.3 × 10–2 cm2/(V s) and a power conversion efficiency (PCE) of 0.3%, respectively. Bulk heterojunction organic photovoltaic devices of p(DPP-TTF) blended with phenyl-C71-butyric acid methyl ester (PC71BM) exhibited a PCE of 1.8%

A novel series of organic semiconductors for OPV and OFET applications

In the last three decades, the search for alternative energy for common fuel sources has been greatly developed. Among the already well-established and developing technologies (wind energy, hydrogen, geothermal energy or hydropower), solar cells have attracted enormous interest. This interest is due to the potentially vast solar energy that can be harvested on the Earth's surface. Currently, solar cells based on inorganic materials are widespread due to their high efficiency, whereas the power conversion efficiency of organic photovoltaics (OPVs), being new technology, is continuously increasing towards that of their inorganic counterparts. The improvement of this promising field is strongly linked to the development of new materials to increase the harvesting properties of the organic solar cell, as well as a better understanding of the physics and the behaviour of every component within the device. In that sense, this thesis presents the synthesis and characterisation of three novel series of organic materials and their performance in organic photovoltaics. Chapter 2 describes the incorporation of a well-known dye (BODIPY) into conjugated polymers. A BODIPY core was co-polymerised with bis-EDOT and bis-EDTT units and their performance in OPVs was studied. Chapter 3 shows the effective fusion of TTF units via a thiophene unit to the main conjugated polymer chain. A fused thieno-TTF moiety was copolymerised with a soluble derivative of DPP and tested in organic photovoltaics and OFETs showing excellent results. Finally, the synthesis and characterisation of two new "small molecules" based on BODIPY-DPP-BODIPY triads are described in Chapter 4. The performance of these two novel compounds in OPVs is currently under study.In the last three decades, the search for alternative energy for common fuel sources has been greatly developed. Among the already well-established and developing technologies (wind energy, hydrogen, geothermal energy or hydropower), solar cells have attracted enormous interest. This interest is due to the potentially vast solar energy that can be harvested on the Earth's surface. Currently, solar cells based on inorganic materials are widespread due to their high efficiency, whereas the power conversion efficiency of organic photovoltaics (OPVs), being new technology, is continuously increasing towards that of their inorganic counterparts. The improvement of this promising field is strongly linked to the development of new materials to increase the harvesting properties of the organic solar cell, as well as a better understanding of the physics and the behaviour of every component within the device. In that sense, this thesis presents the synthesis and characterisation of three novel series of organic materials and their performance in organic photovoltaics. Chapter 2 describes the incorporation of a well-known dye (BODIPY) into conjugated polymers. A BODIPY core was co-polymerised with bis-EDOT and bis-EDTT units and their performance in OPVs was studied. Chapter 3 shows the effective fusion of TTF units via a thiophene unit to the main conjugated polymer chain. A fused thieno-TTF moiety was copolymerised with a soluble derivative of DPP and tested in organic photovoltaics and OFETs showing excellent results. Finally, the synthesis and characterisation of two new "small molecules" based on BODIPY-DPP-BODIPY triads are described in Chapter 4. The performance of these two novel compounds in OPVs is currently under study