Acceptor Copolymers Research Articles

Post‐Polymerization Strategy via Dual Site Clicking for Synthesizing Intrinsically Cross‐Linkable Semiconducting Polymers

ABSTRACTCrosslinked organic semiconductors have opened the way for various fabrication techniques in the field of organic electronics owing to their three‐dimensional network structure with high solvent resistivity. However, recent efforts to synthesize cross‐linkable semiconducting polymers have been limited by their low molecular weights and yields. In this study, this limitation is overcome by a novel post‐polymerization strategy. A reagent with a cross‐linkable functional group, (3‐mercaptopropyl)trimethoxysilane, is attached to a diketopyrrolopyrrole‐based donor–acceptor copolymer (DPPTT) via thioesterification and para‐fluoro‐thiol reaction, modifying two sites simultaneously. This modification preserves the molecular weight and electrical properties of the original polymers. In addition, the use of click chemistry enables high yield (98%) without any purification. The modified DPPTT demonstrated high resistance to organic solvents (80% retention dipped in 1‐chlorobenzene for 1 h). Exploiting this benefit, an ultrathin flexible array of 100 organic field‐effect transistors fabricated using conventional photolithography showed high‐performance reliability. Thus, this study provides a universal strategy to synthesize versatile polymer semiconductors for practical organic electronics. image

A Tricyclic Framework with Integrated B←N and Cyano Dual Functionalization for Superior n‐Type Organic Electronics

Abstractn‐Type conjugated polymers featuring low‐lying lowest unoccupied molecular orbital (LUMO) energy levels are essential for achieving high‐performance n‐type organic thin‐film transistors (OTFTs) and organic thermoelectrics (OTEs). However, the synthesis of acceptors with strong electron‐withdrawing characteristics presents a significant challenge. Herein, a peripheral functionalization strategy is employed on the tricyclic framework anthracene by introducing dual N,O‐bidentate BF2/B(CN)2 groups to enhance its electron‐withdrawing capability. This approach successfully navigates synthetic challenges, leading to the development of two novel acceptor building blocks: DBNF and DBNCN. Compared to the counterparts with a single N,O‐bidentate BF2/B(CN)2 moiety, DBNF and DBNCN exhibit an extended π‐backbone, enhanced molecular packing, and improved electron‐withdrawing properties. Utilizing these innovative acceptor monomers, copolymers, PDBNF and PDBNCN, are synthesized, which exhibit considerably suppressed LUMO ≈−4.0 eV. The deep LUMO of PDBNF together with its favourable bimodal packing orientation leads to remarkable electron mobility of 3.04 cm2 V−1 s−1 with improved stability in OTFTs. Importantly, efficient n‐doping in OTEs is achieved with PDBNCN, exhibiting exceptional conductivity of 95.5 S cm−1 and a maximum power factor of 147.8 μW m−1 K−2—among the highest reported for solution‐processed n‐type polymers. This work underscores the effectiveness of introducing dual B←N and cyano functionalities in attaining high‐performance n‐type plastic electronics.

A Tricyclic Framework with Integrated B←N and Cyano Dual Functionalization for Superior n-Type Organic Electronics.

n-Type conjugated polymers featuring low-lying lowest unoccupied molecular orbital (LUMO) energy levels are essential for achieving high-performance n-type organic thin-film transistors (OTFTs) and organic thermoelectrics (OTEs). However, the synthesis of acceptors with strong electron-withdrawing characteristics presents a significant challenge. Herein, a peripheral functionalization strategy is employed on the tricyclic framework anthracene by introducing dual N,O-bidentate BF2/B(CN)2 groups to enhance its electron-withdrawing capability. This approach successfully navigates synthetic challenges, leading to the development of two novel acceptor building blocks: DBNF and DBNCN. Compared to the counterparts with a single N,O-bidentate BF2/B(CN)2 moiety, DBNF and DBNCN exhibit an extended π-backbone, enhanced molecular packing, and improved electron-withdrawing properties. Utilizing these innovative acceptor monomers, copolymers, PDBNF and PDBNCN, are synthesized, which exhibit considerably suppressed LUMO ≈-4.0 eV. The deep LUMO of PDBNF together with its favourable bimodal packing orientation leads to remarkable electron mobility of 3.04 cm2 V-1 s-1 with improved stability in OTFTs. Importantly, efficient n-doping in OTEs is achieved with PDBNCN, exhibiting exceptional conductivity of 95.5 S cm-1 and a maximum power factor of 147.8 μW m-1 K-2-among the highest reported for solution-processed n-type polymers. This work underscores the effectiveness of introducing dual B←N and cyano functionalities in attaining high-performance n-type plastic electronics.

Correction to “Triethylene Glycol Substituted Diketopyrrolopyrrole‐ and Isoindigo‐Dye Based Donor–Acceptor Copolymers for Organic Light‐Emitting Electrochemical Cells and Transistors”

Correction to “Triethylene Glycol Substituted Diketopyrrolopyrrole‐ and Isoindigo‐Dye Based Donor–Acceptor Copolymers for Organic Light‐Emitting Electrochemical Cells and Transistors”

Synthesis of 1,4‐dihydropyrrolo[3,2‐b]pyrrole‐containing donor–acceptor copolymers and their optoelectronic properties

AbstractDonor–acceptor (D–A)‐conjugated polymers have achieved promising performance metrics in numerous optoelectronic applications that continue to motivate studying structure–property relationships and discovering new materials. Here, the materials toolbox is expanded by synthesizing D–A copolymers where 1,4‐dihydropyrrolo[3,2‐b]pyrrole (DHPP) is directly incorporated into the main chain of D–A copolymers for the first time via direct heteroarylation polymerization. Notably, the synthetic complexity of DHPP‐containing polymers coupled with thieno[3,2‐b]pyrrole‐4,6‐dione (TPD) or 3,6‐bis(2‐thienyl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (Th2DPP) comonomers is calculated to be lower compared to many common conjugated polymers synthesized via direct arylation. The electron‐rich nature of DHPPs when coupled with TPD or DPP enables optoelectronic properties to be manipulated, evident by measuring distinctly different absorbance and redox properties. Additionally, these D–A copolymers demonstrate their potential in organic electronic applications, such as electrochromics and organic photovoltaics. The reported DHPP‐alt‐Th2DPP copolymer is the first DHPP‐based colored‐to‐transmissive electrochrome and achieves power conversion efficiencies of ~2.5% when incorporated into bulk heterojunction solar cells. Overall, the synthetic accessibility of DHPP monomers and their propensity to participate in robust polymerizations highlights the value of establishing structure–property relationships of an underutilized scaffold. These fundamental attributes serve to inform and advance efforts in the development of DHPP‐containing copolymers for various applications.

Poling induced changes in polarization domain structure of polymer ferroelectrics for application in organic thin film transistors

While electrical poling of organic ferroelectrics has been shown to improve device properties, there are challenges in visualizing accompanying structural changes. We observe poling induced changes in ferroelectric domains by applying differential phase contrast (DPC) imaging in the scanning transmission electron microscope, a method that has been used to observe spatial distributions of electromagnetic fields at the atomic scale. In this work, we obtain DPC images from unpoled and electrically poled polyvinylidene fluoride trifluorethylene films and compare their performance in polymer thin film transistors. The vertically poled films show uniform domains throughout the bulk compared to the unpoled film with a significantly higher magnitude of the overall polarization. Thin film transistors comprising a donor–acceptor copolymer as the active semiconductor layer show improved performance with the vertically poled ferroelectric dielectric film compared with the unpoled ferroelectric dielectric film. A poling field of 80–100 MV/m for the dielectric layer yields the best performing transistors; higher than 100 MV/m is seen to degrade the transistor performance. The results are consistent with a reduction in deleterious charge carrier scattering from ferroelectric domain boundaries or interfacial dipoles arising from electrical poling.

Regulating the thermoelectric power factor of donor–acceptor copolymers by heavy chalcogen substitution: a first-principles study

Te substitution of sulfur (S) in PzDPP-based donor–acceptor copolymers enhances n-type power factor, while Se boosts both n-type and p-type power factors. Heavy chalcogen doping strategy shows promise for improving thermoelectric properties.

Enhancing charge transport in isoindigo-based donor–acceptor copolymers by combining ionic doping with polar alkoxy side chains

Side chains of polymers play a crucial role in manipulating polymer interchain interactions, especially polar side chains that promote strong molecular stacking and facilitate ionic diffusion.

Complementary Absorption Pseudo‐Ternary Blend Containing a Y‐Series Block Copolymer Acceptor for Indoor and Outdoor All‐Polymer Photovoltaics

All‐polymer photovoltaics (all‐PPVs) that operate under both indoor and outdoor lighting conditions require active layers with appropriately adjusted optical‐absorption ranges. However, the optical absorption of a conventional donor–acceptor binary blend is restricted to the combined absorption bands of its components. Herein, a new conjugated block copolymer (CBC) acceptor, b‐PYT, is designed by integrating polymer acceptor blocks of wide and narrow bandgaps in a single structure. Such combination results in the wide absorption range (550–850 nm) of b‐PYT that matches the emission of both artificial and solar light. The b‐PYT CBC acceptor is more crystalline than the corresponding random terpolymer, r‐PYT, owing to improved interactions between its macromolecular acceptor units. Despite exhibiting slightly inferior outdoor performance compared to that of devices using the homopolymer BTTP‐T, the PM6:b‐PYT‐based devices deliver superior power conversion efficiency (PCE) under indoor light‐emitting diode (LED) light owing to better matched absorption and emission spectra of b‐PYT and a cold white LED, respectively. Additionally, it is worth highlighting that PM6:b‐PYT‐based all‐PPVs can maintain approximately 87% of the initial PCE even after 600 min of thermal aging at 150 °C, which demonstrates the superior thermal stability compared with those of all‐PPVs that use traditional binary active layers.

Origin of Intrinsic Operational Instability in Organic Field‐Effect Transistors with Aligned High‐Mobility Donor–Acceptor Copolymer Active Layers

AbstractThe origin of intrinsic operational instability in organic field‐effect transistors (OFETs) is discussed by comparing bias stress effects of OFETs with unidirectionally aligned and unaligned active layers of two different semiconducting polymers under vacuum environment. By forming hydrophobic nano‐groove structures on gate dielectric surfaces, a high‐mobility donor–acceptor copolymer, poly[4‐(4,4‐dihexadecyl‐4H‐cyclopenta[1,2‐b:5,4‐b′]‐dithiophen‐2‐yl)‐alt‐[1,2,5]thiadiazolo[3,4‐c]pyridine] (PCDTPT) and a benchmark semicrystalline polymer, poly(2,5‐bis(3‐hexadecylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT‐C16), are successfully aligned. The mobilities of the PCDTPT‐OFETs are higher than those of the PBTTT‐OFETs, but the operational stabilities are lower. Moreover, for both semiconducting polymers, the aligned OFETs exhibit higher mobility but lower operational stability than the unaligned OFETs. These results indicate that an increase in mobility does not necessarily lead to an increase in operational stability. The interface trap density of states analysis reveals that the lower operational stability of PCDTPT‐OFETs is not due to the tail state change but primarily due to the much larger turn‐on voltage shift (ΔVon). The major mechanism causing ΔVon should be the charge carrier transfer from the channel to the gate dielectric. Since the energy barrier limiting the charge carrier transfer decreases with increasing ionization potential of the active layer, the lower operational stability of PCDTPT‐OFETs is attributed to the higher ionization potential of PCDTPT.

Improved Exciton Bandwidth and Edge-On Oriented Ordering of Donor–Acceptor Copolymer Thin Films

Improved Exciton Bandwidth and Edge-On Oriented Ordering of Donor–Acceptor Copolymer Thin Films

Synthesis of Asymmetric Benzotrithiophene/Benzotriselenophene Building Blocks and Their Donor–Acceptor Copolymers: Chalcogen Effect on Face-on/Edge-on Orientations and Charge Transport

Synthesis of Asymmetric Benzotrithiophene/Benzotriselenophene Building Blocks and Their Donor<b>–</b>Acceptor Copolymers: Chalcogen Effect on Face-on/Edge-on Orientations and Charge Transport

New Chemical Dopant and Counterion Mechanism for Organic Electrochemical Transistors and Organic Mixed Ionic-Electronic Conductors.

Organic mixed ionic-electronic conductors (OMIECs) have varied performance requirements across a diverse application space. Chemically doping the OMIEC can be a simple, low-cost approach for adapting performance metrics. However, complex challenges, such as identifying new dopant materials and elucidating design rules, inhibit its realization. Here, these challenges are approached by introducing a new n-dopant, tetrabutylammonium hydroxide (TBA-OH), and identifying a new design consideration underpinning its success. TBA-OH behaves as both a chemical n-dopant and morphology additive in donor acceptor co-polymer naphthodithiophene diimide-based polymer, which serves as an electron transporting material in organic electrochemical transistors (OECTs). The combined effects enhance OECT transconductance, charge carrier mobility, and volumetric capacitance, representative of the key metrics underpinning all OMIEC applications. Additionally, when the TBA+ counterion adopts an "edge-on" location relative to the polymer backbone, Coulombic interaction between the counterion and polaron is reduced, and polaron delocalization increases. This is the first time such mechanisms are identified in doped-OECTs and doped-OMIECs. The work herein therefore takes the first steps toward developing the design guidelines needed to realize chemical doping as a generic strategy for tailoring performance metrics in OECTs and OMIECs.

Synthesis and Characterization of the Donor-Acceptor Conjugated Polymer PBDB-T Implementing Group IV Element Germanium.

Here, we synthesized and characterized a novel two-dimensional (2D) conjugated electron donor-acceptor (D-A) copolymer (PBDB-T-Ge), wherein the substituent of triethyl germanium was added to the electron donor unit of the polymer. The Turbo-Grignard reaction was used to implement the group IV element into the polymer, resulting in a yield of 86%. This corresponding polymer, PBDB-T-Ge, exhibited a down-shift in the highest occupied molecular orbital (HOMO) level to -5.45 eV while the lowest unoccupied molecular orbital (LUMO) level was -3.64 eV. The peaks in UV-Vis absorption and the PL emission of PBDB-T-Ge were observed at 484 nm and 615 nm, respectively.

Molecularly Hybridized Conduction in DPP‐Based Donor–Acceptor Copolymers toward High‐Performance Iono‐Electronics (Small 18/2023)

Iono-Electronics In article 2207554, Aristide Gumyusenge and co-workers demonstrate a copolymerization strategy to engineer novel mixed-ionic electronic conductors with well-balanced conduction at the molecular level. Through chemical fine tuning, these copolymers demonstrate tunable synaptic behaviors enabled by controlled ion insertion and retention. This copolymerization approach is a promising venue for designing novel materials used in future organic body-machine interfaces.

Crystallinity and phase separation induced morphological modulation for efficient ternary all-polymer solar cells

All-polymer solar cells (all-PSCs) have attracted enormous attention and achieved significant progress in recent years due to their long-term stability and excellent film stretchability. However, the problem of morphology control in bulk-heterojunction (BHJ) films due to highly entangled polymeric chains hinders the further improvement of device performance. In this work, we obtained fine-tuned photoactive layer morphology through reconstructed microstructure induced by steric effects to realize an improved device performance in ternary all-PSCs. The large tetrahexylphenyl substituents on the backbone of naphthalene diimide–indacenodithienothiophene based copolymer acceptor BL-102 bring forth the steric-hindrance effect and influence intermolecular interactions. Therefore, the copolymer BL-102 delivers the property of suppressed self-aggregation, causing reconstructed crystalline features and morphology in blending films. The ternary devices tended to reduce the excessive phase separation by suppressing the aggregation of original polymers but to promote intermixing behaviors. Therefore, the optimal BHJ film manifested a well-formed bi-continuous interpenetrating nanoscale network with a larger π–π stacking coherence length and ordered face-on molecular orientation. Hence, a faster electron transfer (ET) and hole transfer (HT) process combined with balanced charge carrier mobilities can be achieved to enhance the overall device performance. This work provides an effective method to regulate the photoactive layer morphology of all-PSCs through structurally steric hindrance effects and demonstrate the significance of ternary-blending strategy induced nanoscale morphology modulation for fabricating highly efficient all-PSCs.

Through-Space Charge-Transfer Thermally Activated Delayed Fluorescence Alternating Donor–Acceptor Copolymers for Nondoped Solution-Processable OLEDs

Through-Space Charge-Transfer Thermally Activated Delayed Fluorescence Alternating Donor–Acceptor Copolymers for Nondoped Solution-Processable OLEDs

Electron Transport in Donor-Acceptor Copolymer and Methanofullerene Derivative Organic Photovoltaic Blend

Recently, organic photovoltaics (OPVs) based on the blends of donor–acceptor (D–A) copolymers as efficient p-type materials and fullerene derivatives as acceptors have attracted considerable attention. In this paper, electron transport and electrical properties in a blend of D–A copolymer DTS-C0(F2) and methanofullerene derivative PC71BM are investigated. From an analysis of the temperature dependence of the current density–voltage (J − V) characteristics of electron-only device based on DTS-C0(F2):PC71BM blend, it is found that consistent descriptions for the experimental measurements are obtained using both the improved extended Gaussian disorder model (IEGDM) and the extended correlated disorder model (ECDM), within which spatial correlations between the transport site energies are absent and are included, respectively. By comparing the model parameters with the typical values of organic semiconductors, we view the more realistic intersite distance obtained using the IEGDM (1.9 nm) compared to the value obtained using the ECDM (0.48 nm) as an indication that in DTS-C0(F2):PC71BM blend correlations between the transport site energies are absent. Furthermore, it is shown that the effective mobility in DTS-C0(F2):PC71BM blend gradually increases with increasing temperature.

Molecular design of two-dimensional donor-acceptor covalent organic frameworks for intramolecular singlet fission.

Two-dimensional covalent organic frameworks (2D-COFs) constitute an ideal platform for the design of novel optoelectronic materials. In this work, the donor-acceptor copolymer strategy for intramolecular singlet fission (iSF) is revisited and applied for the tailored design of a functional 2D-COF with iSF capabilities.

Synthesis of angular-shaped naphthodithiophenediimide and its donor–acceptor copolymers as nonvolatile polymer additives for organic solar cells

A new angular-shaped naphthodithiophene diimide (aNDTI) is designed and synthesized. The aNDTI-containing polymers are used as non-volatile additives to improve the efficiency of organic solar cells.