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Engineering the molecular structure of conjugated polymers is key to advancing the field of organic electronics. In this work, we synthesized a molecularly encapsulated version of the naphthalene diimide bithiophene copolymer PNDIT2, which is among the most popular high charge mobility organic semiconductors in n-type field-effect transistors and non-fullerene acceptors in organic photovoltaic blends. The encapsulating macrocycles shield the bithiophene units while leaving the naphthalene diimide units available for intermolecular interactions. With respect to PNDIT2, the encapsulated counterpart displays an increased backbone planarity. Molecular encapsulation prevents preaggregation of the polymer chains in common organic solvents, while it permits π-stacking in the solid state and promotes thin film crystallinity through an intermolecular-lock mechanism. Consequently, n-type semiconducting behavior is retained in field-effect transistors, although charge mobility is lower than in PNDIT2 due to the absence of the fibrillar microstructure that originates from preaggregation in solution. Hence, molecularly encapsulating conjugated polymers represent a promising chemical strategy to tune the molecular interaction in solution and the backbone conformation and to consequently control the nanomorphology of casted films without altering the electronic structure of the core polymer.

The combination of computational methods and advanced characterization techniques is used to highlight the role of the intramolecular hydrogen bond in thienyldiketopyrrolopyrrole (ThDPPTh) copolyme...

Doping is a common strategy in the field of semiconductor technology but its employment in organic photodetectors (OPDs) has been limited due to the typical uncontrollable increase of the dark currents. This study introduces three different molecular dopants, including p-type tris(pentafluorophenyl)borane, n-type benzyl viologen, and (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-phenyl)dimethylamine, for near-infrared poly[[2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-alt-[3′,3′′-dimethyl-2,2′:5′,2′′-terthiophene]-5,5′′-diyl]:[6,6]-phenyl C61 butyric acid methyl ester (PMDPP3T:PC61BM) bulk-heterojunction OPDs. The results show that OPDs with optimal 0.02 wt% dopants exhibit low dark current (3.18 × 10−8 A cm−2), high detectivity (5.56 × 1012 Jones), and good environmental stability for ∼2 months. These doped OPDs are further used for pulse wave monitoring, which exhibit stable waveforms and can distinguish slow and fast heartbeat rates.

Atom-economic protocols for the synthesis of poly(indacenodithiophene-alt-benzothiadiazole) (PIDTBT) are presented in which all C–C coupling steps are achieved by direct arylation. Using two different synthetic pathways, PIDTBT copolymers with different side chains (hexylphenyl, octylphenyl, dodecyl, methyl/2-octyldodecylphenyl, 2-octyldodecylphenyl/2-octyldodecylphenyl) and molecular weight (MW) are prepared. Route A makes use of direct arylation polycondensation (DAP) of indacenodithiophene (IDT) and 4,7-dibromo-2,1,3-benzothiadiazole (BTBr2) leading to PIDTBT in high yields, with adjustable MW and without indications for structural defects. Route B starts from a polyketone precursor also prepared by DAP following cyclization. While route B allows introduction of asymmetric side chains at the IDT unit, polymer analogous cyclization gives rise to defect formation. The absorption coefficient of PIDTBT with alkylphenyl side chains made by route A increases with MW. Field-effect hole mobilities around ∼10−2 cm2 V−1 s−1 are molecular weight-independent, which is ascribed to a largely amorphous thin film morphology. PIDTBT with linear dodecyl side (C12) chains exhibits a bathochromic shift (20 nm), in agreement with theory, and more pronounced vibronic contributions to absorption spectra. In comparison to alkylphenyl side chains, C12 side chains allow for increased order in thin films, a weak melting endotherm and lower energetic disorder, which altogether explain substantially higher field-effect hole mobilities of ∼ 10−1 cm2 V−1 s−1.

Molecular doping has recently been shown to improve the operating characteristics of organic photovoltaics (OPVs). Here, we prepare neutral Diquat (DQ) and use it as n-dopant to improve the perform...

Recent efforts in the field of organic photodetectors (OPD) have been focused on extending broadband detection into the near-infrared (NIR) region. Here, two blends of an ultralow bandgap push–pull polymer TQ-T combined with state-of-the-art non-fullerene acceptors, IEICO-4F and Y6, are compared to obtain OPDs for sensing in the NIR beyond 1100 nm, which is the cut off for benchmark Si photodiodes. It is observed that the TQ-T:IEICO-4F device has a superior IR responsivity (0.03 AW-1 at 1200 nm and −2 V bias) and can detect infrared light up to 1800 nm, while the TQ-T:Y6 blend shows a lower responsivity of 0.01 AW-1. Device physics analyses are tied with spectroscopic and morphological studies to link the superior performance of TQ-T:IEICO-4F OPD to its faster charge separation as well as more favorable donor–acceptor domains mixing. In the polymer blend with Y6, the formation of large agglomerates that exceed the exciton diffusion length, which leads to high charge recombination, is observed. An application of these devices as biometric sensors for real-time heart rate monitoring via photoplethysmography, utilizing infrared light, is demonstrated.

[EN] Solution-processed, large-area, and flexible electronics largely relies on the excellent electronic properties of sp(2)-hybridized carbon molecules, either in the form of pi-conjugated small molecules and polymers or graphene and carbon nanotubes. Carbon with sp-hybridization, the foundation of the elusive allotrope carbyne, offers vast opportunities for functionalized molecules in the form of linear carbon atomic wires (CAWs), with intriguing and even superior predicted electronic properties. While CAWs represent a vibrant field of research, to date, they have only been applied sparingly to molecular devices. The recent observation of the field-effect in microcrystalline cumulenes suggests their potential applications in solution-processed thin-film transistors but concerns surrounding the stability and electronic performance have precluded developments in this direction. In the present study, ideal field-effect characteristics are demonstrated for solution-processed thin films of tetraphenyl[3]cumulene, the shortest semiconducting CAW. Films are deposited through a scalable, large-area, meniscus-coating technique, providing transistors with hole mobilities in excess of 0.1 cm(2 )V(-1 )s(-1), as well as promising operational stability under dark conditions. These results offer a solid foundation for the exploitation of a vast class of molecular semiconductors for organic electronics based on sp-hybridized carbon systems and create a previously unexplored paradigm. E.G.F. acknowledges the support through the EU Horizon 2020 research and innovation program, H2020-FETOPEN-01-2018-2020 (FET-Open Challenging Current Thinking), "LION-HEARTED", grant agreement no. 828984. C.S.C. acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program ERC-Consolidator Grant (ERC CoG 2016 EspLORE grant agreement no. 724610, website: ). R.R.T. acknowledges funding from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI). This work was partially supported by the European Union's H2020-EU.4.b. - Twinning of research institutions "GREENELIT", grant agreement number 951747. GIWAXS experiments were performed at BL11 NCD-SWEET beamline at ALBA Synchrotron (Spain) with the collaboration of ALBA staff. This work was in part carried out at Polifab, the micro- and nanotechnology centre of the Politecnico di Milano. Open access funding provided by Istituto Italiano di Tecnologia within the CRUI-CARE Agreement.

The low carrier mobility of organic semiconductors and the high parasitic resistance and capacitance often encountered in conventional organic Schottky diodes, hinder their deployment in emerging radio frequency (RF) electronics. Here we overcome these limitations by combining self-aligned asymmetric nanogap electrodes (∼25 nm) produced by adhesion-lithography, with a high mobility organic semiconductor and demonstrate RF Schottky diodes able to operate in the 5G frequency spectrum. We used C16 IDT-BT, as the high hole mobility polymer, and studied the impact of p-doping on the diode performance. Pristine C16 IDT-BT-based diodes exhibit maximum intrinsic and extrinsic cutoff frequencies (fC ) of >100 and 6 GHz, respectively. This extraordinary performance is attributed primarily to the planar nature of the nanogap channel and the diode's small junction capacitance (< 2 pF). Doping of C16 IDT-BT with the molecular p-dopant C60 F48 , improves the diode's performance further by reducing the series resistance resulting to intrinsic and extrinsic fC of >100 and ∼14 GHz respectively, while the DC output voltage of a RF rectifier circuit increases by a tenfold. Our work highlights the importance of the planar nanogap architecture and paves the way for the use of organic Schottky diodes in large-area radio frequency electronics of the future. This article is protected by copyright. All rights reserved.

This article is part of the Organic Bioelectronics special issue., Electronic doping in organic materials has remained an elusive concept for several decades. It drew considerable attention in the early days in the quest for organic materials with high electrical conductivity, paving the way for the pioneering work on pristine organic semiconductors (OSCs) and their eventual use in a plethora of applications. Despite this early trend, however, recent strides in the field of organic electronics have been made hand in hand with the development and use of dopants to the point that are now ubiquitous. Here, we give an overview of all important advances in the area of doping of organic semiconductors and their applications. We first review the relevant literature with particular focus on the physical processes involved, discussing established mechanisms but also newly proposed theories. We then continue with a comprehensive summary of the most widely studied dopants to date, placing particular emphasis on the chemical strategies toward the synthesis of molecules with improved functionality. The processing routes toward doped organic films and the important doping–processing–nanostructure relationships, are also discussed. We conclude the review by highlighting how doping can enhance the operating characteristics of various organic devices., This work was from King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award nos. OSR-2018-CARF/CCF-3079 and OSR-2019- CRG8-4095.3. F.A. acknowledges the support from The Wilkinson Charitable Foundation. C.M. acknowledges financial support from the Swedish Research Council (grant no. 2018- 03824) and the Knut and Alice Wallenberg Foundation through a Wallenberg Academy Fellowship Prolongation grant.

There is a growing demand to attain organic materials with high electron mobility, μ e, as current reliable reported values are significantly lower than those exhibited by their hole mobility counterparts. Here, it is shown that a well‐known nonfullerene‐acceptor commonly used in organic solar cells, that is, BTP‐4F (aka Y6), enables solution‐processed organic thin‐film transistors (OTFT) with a μ e as high as 2.4 cm2 V−1 s−1. This value is comparable to those of state‐of‐the‐art n‐type OTFTs, opening up a plethora of new possibilities for this class of materials in the field of organic electronics. Such efficient charge transport is linked to a readily achievable highly ordered crystalline phase, whose peculiar structural properties are thoroughly discussed. This work proves that structurally ordered nonfullerene acceptors can exhibit intrinsically high mobility and introduces a new approach in the quest of high μ e organic materials, as well as new guidelines for future materials design., n‐channel organic thin‐film transistors exhibiting electron mobility values as high as 2.4 cm2 V−1 s−1 are produced with the benchmark nonfullerene acceptor used in organic solar cell, that is, BTP‐4F (aka Y6). These properties stem from crystallization of Y6 in a crystalline structure featuring molecularly flat, highly ordered, and textured domains.

Blade-coating is a roll-to-roll (R2R) compatible processing technique and has the potential to address the industry's needs for scalable manufacturing of future organic electronics. Here we investigate the applicability of blade-coating for the fabrication of organic thin-film transistors (OTFTs) based on best-in-class organic semiconducting blends comprised of the conjugated small-molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), and the conjugated polymer poly(indacenodithiophene-co-benzothiadiazole) (C16IDT-BT). We show that the operating characteristics of blade-coated transistors consistently outperform devices prepared via spin-coating, showcasing the compatibility of the technique. Introducing the molecular p-dopant C60F48 into the binary C8-BTBT:C16IDT-BT blend formulation, in combination with carefully optimized blade-coating conditions, helps to enhance the performance of the ensuing transistors further resulting in a maximum hole mobility of ≈14 cm2 V−1 s−1, and an all-around improvement of the device operating characteristics. Our results show that p-doped blend OTFTs can be manufactured using industry relevant processing techniques without sacrificing their state-of-the-art performance.

Here we have investigated the influence of the molecular length and structure of a series of BTI-based semiconductors on the stabilization of charged states in solution by in situ UV/Vis/NIR spectroelectrochemistry and in the solid state, at the active interface of operational OFET devices, by charge modulation spectroscopy (CMS). Interestingly, we found that charge stabilization in the shortest system of the series (BTI2) is strongly favored via a π-dimer formation which, in addition to higher thin film microstructural ordering, results in a greater electron mobility in organic field effect transistors (OFETs). The experimental results were interpreted using TD-DFT and DFT quantum chemical calculations at different levels of theory.

Organic electronics has been steadily evolving, with improving performances, including unrivaled mechanical properties. One of the main technological trends aims at thinner and lighter form factors, toward the realization of ultraflexible and conformable large-area electronic devices, capable of withstanding harsh mechanical stresses and therefore finding applications where rigid or brittle technologies would fail. Pursuing this objective, a critical role is known to be played by the substrate, whose thickness needs to be reduced as much as possible while maintaining its processability. Ultrathin substrates and a neutral plane strategy have therefore been exploited to realize ultrathin organic devices; however, ultraflexible complementary circuits based on printed organic semiconductors, realized by means of high-throughput and large-area techniques, have not been realized so far. In this work, all-polymer organic field effect transistors and complementary inverters have been printed onto a micrometer-thin parylene substrate, subsequently also used as a top isolation layer in order to place the active components in the neutral plane of stresses. These devices show appropriate low voltage operation, with supply voltages as low as 2 V, and retain stable and uniform performances upon the application of harsh mechanical stresses, such as rolling and crumpling. These results represent the first demonstration of semi-transparent and fully organic crumpable printed electronics, and pave the way toward the realization of more complex complementary logic circuits, laying the foundation for their widespread and cost-effective integration into consumer products.

Organic solar cells incorporating non-fullerene acceptors (NFAs) have reached remarkable power conversion efficiencies of over 18%. Unlike fullerene derivatives, NFAs tend to crystallize from solutions, resulting in bulk heterojunctions that include a crystalline acceptor phase. This must be considered in any morphology-function models. Here, it is confirmed that high-performing solution-processed indacenodithienothiophene-based NFAs, i.e., ITIC and its derivatives ITIC-M, ITIC-2F, and ITIC-Th, exhibit at least two crystalline forms. In addition to highly ordered polymorphs that form at high temperatures, NFAs arrange into a low-temperature metastable phase that is readily promoted via solution processing and leads to the highest device efficiencies. Intriguingly, the low-temperature forms seem to feature a continuous network that favors charge transport despite of a poorly order along the π–π stacking direction. As the optical absorption of the structurally more disordered low-temperature phase can surpass that of the more ordered polymorphs while displaying comparable—or even higher—charge transport properties, it is argued that such a packing structure is an important feature for reaching highest device efficiencies, thus, providing guidelines for future materials design and crystal engineering activities., This work is supported by the Ministerio de Ciencia e Innovacion/FEDER (under Ref. PGC2018-094620-A-I00 and PGC2018-095411-B-I00, CEX2019-000917-S and PGC2018- 095411-B-100) and the Basque Country Government (Ref. PIBA19-0051). S.M. is grateful to POLYMAT for the doctoral scholarship. The authors thank A. Arbe, A. Alonso-Mateo, L. Hueso for their support and access to characterization tools. The authors also thank the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF). GIWAXS experiments were performed at BL11 NCD-SWEET beamline at ALBA Synchrotron (Spain) with the collaboration of ALBA staff. J.M and E.F.-G. acknowledge support through the European Union's Horizon 2020 research and innovation program, H2020-FETOPEN 01- 2018-2020 (FET-Open Challenging Current Thinking), ‘LION-HEARTED', grant agreement n. 828984. J.M and N.S. would like to thank the financial support provided by the IONBIKE RISE project, which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 823989. N.S. and A.K. and A.B. furthermore are grateful to the U.S. National Science Foundation (NSF) for support via project # 1905901 within NSF’s Division of Materials Research. A. S. and M. C. acknowledge financial support by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program “HEROIC,” grant agreement 638059. This work was partially carried out at Polifab, the micro- and nanotechnology center of the Politecnico di Milano. .C.M. thanks the Knut and Alice Wallenberg Foundation for funding through the project “Mastering Morphology for Solution-borne Electronics”.

Structural defects in semiconducting conjugated polymers are usually suspected to deteriorate their properties and device performance and therefore complicate batch-to-batch reproducibility. This s...

Substrate engineering for steering cell growth is a wide and well-established area of research in the field of modern biotechnology. Here we introduce a micromachining technique to pattern an inert, transparent polymer matrix blended with a photoactive polymer. We demonstrate that the obtained scaffold combines the capability to align with that to photostimulate living cells. This technology can open up new and promising applications, especially where cell alignment is required to trigger specific biological functions, e.g. generate powerful and efficient muscle contractions following an external stimulus., Comment: 30 pages, 7 images in main text, 5 images in supporting

It is well established that for organic photodetectors (OPDs) to compete with their inorganic counterparts, low dark currents at reverse bias must be achieved. Here, two rhodanine-terminated nonfullerene acceptors O-FBR and O-IDTBR are shown to deliver low dark currents at -2 V of 0.17 and 0.84 nA cm-2, respectively, when combined with the synthetically scalable polymer PTQ10 in OPD. These low dark currents contribute to the excellent sensitivity to low light of the detectors, reaching values of 0.57 μW cm-2 for PTQ10:O-FBR-based OPD and 2.12 μW cm-2 for PTQ10:O-IDTBR-based OPD. In both cases, this sensitivity exceeds that of a commercially available silicon photodiode. The responsivity of the PTQ10:O-FBR-based OPD of 0.34 AW-1 under a reverse bias of -2 V also exceeds that of a silicon photodiode. Meanwhile, the responsivity of the PTQ10:O-IDTBR of 0.03 AW-1 is limited by the energetic offset of the blend. The OPDs deliver high specific detectivities of 9.6 × 1012 Jones and 3.3 × 1011 Jones for O-FBR- and O-IDTBR-based blends, respectively. Both active layers are blade-coated in air, making them suitable for high-throughput methods. Finally, all three of the materials can be synthesized at low cost and on a large scale, making these blends good candidates for commercial OPD applications.

Organic mixed conductors find use in batteries, bioelectronics technologies, neuromorphic computing, and sensing. While great progress has been achieved, polymer-based mixed conductors frequently experience significant volumetric changes during ion uptake/rejection, i.e., during doping/de-doping and charging/discharging. Although ion dynamics may be enhanced in expanded networks, these volumetric changes can have undesirable consequences, e.g., negatively affecting hole/electron conduction and severely shortening device lifetime. Here, the authors present a new material poly[3-(6-hydroxy)hexylthiophene] (P3HHT) that is able to transport ions and electrons/holes, as tested in electrochemical absorption spectroscopy and organic electrochemical transistors, and that exhibits low swelling, attributed to the hydroxylated alkyl side-chain functionalization. P3HHT displays a thickness change upon passive swelling of only +2.5%, compared to +90% observed for the ubiquitous poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, and +10 to +15% for polymers such as poly(2-(3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-[2,2'-bithiophen]-5-yl)thieno[3,2-b]thiophene) (p[g2T-TT]). Applying a bias pulse during swelling, this discrepancy becomes even more pronounced, with the thickness of P3HHT films changing by10% while that of p(g2T-TT) structures increases by +75 to +80%. Importantly, the initial P3HHT film thickness is essentially restored after de-doping while p(g2T-TT) remains substantially swollen. The authors, thus, expand the materials-design toolbox for the creation of low-swelling soft mixed conductors with tailored properties and applications in bioelectronics and beyond.

Carbyne and linear carbon structures based on sp-hybridization are attractive targets as the ultimate one-dimensional system (i.e., one-atom in diameter) featuring wide tunability of optical and electronic properties. Two possible structures exist for sp-carbon atomic wires: (a) the polyynes with alternated single-triple bonds and (b) the cumulenes with contiguous double bonds. Theoretical studies predict semiconducting behavior for polyynes, while cumulenes are expected to be metallic. Very limited experimental work, however, has been directed toward investigating the electronic properties of these structures, mostly at the single-molecule or monolayer level. However, sp-carbon atomic wires hold great potential for solution-processed thin-film electronics, an avenue not exploited to date. Herein, we report the first field-effect transistor (FET) fabricated employing cumulenic sp-carbon atomic wires as a semiconductor material. Our proof-of-concept FET device is easily fabricated by solution drop casting and paves the way for exploiting sp-carbon atomic wires as active electronic materials.

The development of cheap and reliable time-temperature indicators (TTIs) can greatly improve customer satisfaction with respect to the correct handling and storage of perishable goods. A series of new irreversible thermochromic squaraine dyes enables the preparation of simple TTIs whose time-temperature regime can be controlled by selection of the appropriate molecule/substrate combinations.

Polymer blends are broadly important in chemical science and chemical engineering and have led to a wide range of commercial products, however their precise structure and phase morphology is often not well understood. Here we show for the first time that π-conjugated polytellurophenes and high-density polyethylene form blends that can serve as active layers in field-effect transistor devices and can be characterized by a variety of element-specific imaging techniques such as STEM and EDX. Changing the hydrocarbon content and degree of branching on the polytellurophene side-chain leads to a variety of blend structures, and these variations can be readily visualized. Characterization by electron microscopy is complemented by topographic and X-ray methods to establish a nano- to micro-scale picture of these systems. We find that blends that possess microscale networks function best as electronic devices; however, contrary to previous notions a strong correlation between nanofiber formation and electrical performance is not observed. Our work demonstrates that use of organometallic polymers assists in clarifying relevant structure–property–function relationships in multicomponent systems such as semiconductor:insulator blends and sheds light on the structure development in polymer:polymer blends including crystallization, phase separation, and formation of supramolecular arrangements.

It has been demonstrated that the 0-0 absorption transition of poly(3-hexylthiophene) (P3HT) in blends with poly(ethylene oxide) (PEO) could be rationally tuned through the control of the liquid–liquid phase separation process during solution deposition. Pronounced J-like aggregation behavior, characteristic for systems of a low exciton band width, was found for blends where the most pronounced liquid–liquid phase separation occurred in solution, leading to domains of P3HT and PEO of high phase purity. Since liquid–liquid phase separation could be readily manipulated either by the solution temperature, solute concentration, or deposition temperature, to name a few parameters, our findings promise the design from the out-set of semiconductor:insulator architectures of pre-defined properties by manipulation of the interaction parameter between the solutes as well as the respective solute:solvent system using classical polymer science principles. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 304–310

In recent years, immense efforts in the organic electronics field have led to unprecedented progress and to devices of ever increasing performance. Despite these advances, new opportunities are sought in order to widen the applications of organic-based technologies and expand their functionalities and features. For this purpose, use of multicomponent systems seems an interesting approach in view of, e.g., increasing the mechanical flexibility and stability of organic electronic products as well as introducing other features such as self-encapsulation. One specific strategy is based on blending polymeric insulators with organic semiconductors; which has led to a desired improvement of the mechanical properties of organic devices, producing in certain scenarios robust and stable architectures. Here we discuss the working principle of semiconductor:insulator blends, examining the different approaches that have recently been reported in literature. We illustrate how organic field-effect transistors (OFET)s and organic solar cells (OPV)s can be fabricated with such systems without detrimental effects on the resulting device characteristics even at high contents of the insulator. Furthermore, we review the various properties that can be enhanced and/or manipulated by blending including air stability, mechanical toughness, H- vs. J-aggregation, etc.

Chemical design criteria for materials for bioelectronics applications using a series of copolymer derivatives based on poly(3-hexylthiophene) are established. Directed chemical design via side-chain functionalization with polar groups allows manipulation of ion transport and ion-to-electron transduction. Insights gained will permit increased use of the plethora of materials employed in the organic electronics area for application in the bioelectronics field.

Indacenodithiophene (IDT) based materials are emerging high performance conjugated polymers for use in efficient organic photovoltaics and transistors. However, their preparation generally suffers from long reaction sequences and is often accomplished using disadvantageous Stille couplings. Herein, we present detailed synthesis pathways to IDT homopolymers using C-H activation for all C-C coupling steps. Polyketones are first prepared by direct arylation polycondensation (DAP) in quantitative yield and further cyclized polymer analogously. This protocol is suitable for obtaining structurally well-defined IDT homopolymers, provided that the conditions for cyclization are chosen appropriately and that side reactions are suppressed. Moreover, this polymer analogous pathway gives rise to asymmetric side chain patterns, which allows to fine tune physical properties. Alternatively, IDT homopolymers can be obtained via oxidative direct arylation polycondensation of IDT monomers (oxDAP), leading to IDT homopolymers with similar properties but at reduced yield. Detailed characterization by NMR, IR, UV-vis and PL spectroscopy, and thermal properties, is used to guide synthesis and to explain varying field-effect transistor hole mobilities in the range of 10-6- 10-3 cm2/Vs.

The addition of a third component to a donor:acceptor blend is a powerful tool to enhance the power conversion efficiency of organic solar cells. Featuring a similar operating mechanism, organic photodetectors are also expected to benefit from this approach. Here, we fabricated ternary organic photodetectors, based on a polymer donor and two nonfullerene acceptors, resulting in a low dark current of 0.42 nA cm−2 at −2 V and a broadband specific detectivity of 1012 Jones. We found that exciton recombination in the binary blend is reduced in ternary devices due to the formation of a pseudo-binary microstructure with mixed donor–acceptor phases. With this approach a wide range of intermediate open-circuit voltages is accessible, without sacrificing light-to-current conversion. This results in ternary organic photodetector (TOPD) with improved Responsivity values in the near-infrared. Moreover, morphology analyses reveal that TOPD devices showed improved microstructure ordering and consequentially higher charge carrier mobilities compared to the reference devices.