Acceptor Polymers Research Articles

Luminescence Behavior and Acceptor Effects of Ambipolar Polymeric Electret on Photorecoverable Organic Field‐Effect Transistor Memory

AbstractPhotorecovery systems are considered to be a potential technology in photosensor, green energy‐saving, and high‐speed communication applications (light‐fidelity). However, the role of photoactive‐electret and semiconductor in the photorecovery system is still unintelligible. Herein, triphenylamine (TPA)‐based donor–acceptor polymers are designed as electrets with more effective excitons dissociation for organic field‐effect transistor memory equipped with photosensitive and photorecoverable response. By modifying TPA‐derived conjugated polymers with various electron‐withdrawing groups (PTPA‐CN, PTPA‐CNBr, and PTPA‐3CN), the obtained PTPAs induce disparate luminescent behaviors in the aggregated state. PTPA‐CN and PTPA‐CNBr exhibit aggregation‐induced emission (AIE) featuring the energy dissipation of partial photoexcited excitons through radiation, while PTPA‐3CN turns to aggregation‐caused quenching (ACQ) behavior leading considerable number of nonemissive excitons which can directly recombine with charged medium, an electret containing trapped charges. Pentacene‐based transistor devices incorporated with studied photoactive electrets are constructed for mechanism investigation. The results demonstrate that photorecovery response ability of ACQ‐polymer displays much faster than that of AIE‐polymers, PTPA‐CN, and PTPA‐CNBr, upon UV light irradiation, attributing to the intensely electron‐withdrawing ability of acceptor attached on the conjugated skeleton. The ACQ‐electret device behaves superior memory switching performance with reliable endurance characteristics under the cycling stress of electrical‐programming and optical‐erasing operations, demonstrating the feasibility for organic optoelectronic applications.

Heat transfer in photovoltaic polymers and bulk‐heterojunctions investigated by scanning photothermal deflection technique

AbstractOrganic semiconductors in electronic devices usually have poor thermal conduction which could trap considerable amount of heat, inducing operational instability and reducing device lifetime, limiting commercialization potential. Despite the technological essence to understand and enhance device heat‐dissipation, related studies on organic semiconductors are very limited. In this study, the authors show that the scanning photothermal deflection technique can be employed to study the thermal transport in thin films of organic photovoltaic (OPV) polymers and bulk‐heterojunctions (BHJs), with a simple empirical correction for the extrinsic experimental configuration. Phonons are identified to dominate the thermal transport due to the low carrier mobility. For OPV semiconductors, the positive correlation between the thermal diffusivity and the molecular planarity, – stacking and crystallinity is demonstrated. High‐performance 2D polymers such as PM6 can possess values comparable to alloys like stainless steel. In BHJs, using a polymeric acceptor can retain high thermal diffusivities compared to fullerene and ITIC acceptors, attributed to the efficient heat transfer within the polymer chains. The results offer not only a simple, highly customizable but sensitive experimental method for thermal transport in OPV systems, but also insights into the phonon dynamics and clinical investigations for thermal stability, pushing forward strategic material design.

Side Chain Engineered Naphthalene Diimide-Based Terpolymer for Efficient and Mechanically Robust All-Polymer Solar Cells

The recent evolution of new polymer acceptors (PAs) using small-molecule building blocks with high light absorption has significantly increased the power conversion efficiency (PCE) of all-polymer ...

Semiconducting polymer nanoparticles for photothermal ablation of colorectal cancer organoids

Colorectal cancer (CRC) treatment is currently hindered by micrometastatic relapse that cannot be removed completely during surgery and is often chemotherapy resistant. Targeted theranostic nanoparticles (NPs) that can produce heat for ablation and enable tumor visualization via their fluorescence offer advantages for detection and treatment of disseminated small nodules. A major hurdle in clinical translation of nanoparticles is their interaction with the 3D tumor microenvironment. To address this problem tumor organoid technology was used to evaluate the ablative potential of CD44-targeted polymer nanoparticles using hyaluronic acid (HA) as the targeting agent and coating it onto hybrid donor acceptor polymer particles (HDAPPs) to form HA-HDAPPs. Additionally, nanoparticles composed from only the photothermal polymer, poly[4,4-bis(2-ethylhexyl)-cyclopenta[2,1-b;3,4-b’]dithiophene-2,6-diyl-alt-2,1,3-benzoselenadiazole-4,7-diyl] (PCPDTBSe), were also coated with HA, to form HA-BSe NPs, and evaluated in 3D. Monitoring of nanoparticle transport in 3D organoids revealed uniform diffusion of non-targeted HDAPPs in comparison to attenuated diffusion of HA-HDAPPs due to nanoparticle-matrix interactions. Computational diffusion profiles suggested that HA-HDAPPs transport may not be accounted for by diffusion alone, which is indicative of nanoparticle/cell matrix interactions. Photothermal activation revealed that only HA-BSe NPs were able to significantly reduce tumor cell viability in the organoids. Despite limited transport of the CD44-targeted theranostic nanoparticles, their targeted retention provides increased heat for enhanced photothermal ablation in 3D, which is beneficial for assessing nanoparticle therapies prior to in vivo testing.

Synthesis and Electronic Properties of Diketopyrrolopyrrole-Based Polymers with and without Ring-Fusion.

Diketopyrrolopyrroles (DPP) have been recognized as a promising acceptor unit for construction of semiconducting donor–acceptor (D–A) polymers, which are typically flanked by spacers such as thiophene rings via a carbon–carbon single bond formation. It may suffer from a decrease in the coplanarity of the molecules especially when bulky side chains are installed. In this work, the two N atoms in the DPP unit are further fused with C-3 of the two flanking thiophene rings, yielding a π-expanded, very planar fused-ring building block (DPPFu). A novel DPPFu-based D–A copolymer (PBDTT-DPPFu) was successfully synthesized, consisting of a benzo[1,2-b:4,5-b′]dithiophene (BDTT) unit as a donor and a DPPFu unit as an acceptor. For comparison, the unfused DPP-based counterpart PBDTT-DPP was also synthesized. Two dodecyl alkyl chains were attached to thiophene rings of DPP moieties to ensure good solubility of the DPPFu-based polymer. The influence of the ring-fusion effect on their structure, photophysical properties, electronic properties, molecular packing, and charge transport properties is investigated. Ring-fusion enhances the intermolecular interactions of PBDTT-DPPFu polymer chains as indicated by density functional theory calculation and analysis of electrostatic potential and van der Waals potential and results in significantly improved molecular packing for both the in-plane and out-of-plane directions as suggested by X-ray measurements. Finally, we correlate the molecular packing to the device performance by fabricating field-effect transistors based on these two polymers. The charge carrier mobility of the ring-fused polymer PBDTT-DPPFu is significantly higher as compared to the PBDTT-DPP polymer without ring-fusion, although PBDTT-DPPFu exhibited a much lower number-average molecular weight of 17 kDa as compared to PBDTT-DPP with a molecular weight of 108 kDa. The results from our comparative study provide a robust way to increase the interchain interaction by ring-fusion-promoted coplanarity.

Highly Efficient and Stable All-Polymer Solar Cells Enabled by Near-Infrared Isomerized Polymer Acceptors

One of the most promising approaches to achieving high-performance all-polymer solar cells (all-PSCs) is to develop near-infrared polymer acceptors (PAs) constructed from n-type fused-ring electron...

A polymer acceptor containing the B←N unitfor all-polymer solar cells with 14% efficiency

A new polymer acceptor is designed by copolymerizing a small molecular acceptor with an electron-accepting building block based on the B←N unit. The all polymer solar cell with the polymer acceptor shows a power conversion efficiency of 14.3%.

Research Progress in Organic Solar Cells Based on Small Molecule Donors and Polymer Acceptors

Research Progress in Organic Solar Cells Based on Small Molecule Donors and Polymer Acceptors

Constructing a new polymer acceptor enabled non-halogenated solvent-processed all-polymer solar cell with an efficiency of 13.8.

A new polymer acceptor, PS1, was developed by connecting the non-fullerene acceptor building block of dithienothiophen[3,2-b]pyrrolobenzotriazole capped with 3-(dicyanomethylidene)-indan-1-one through a thiophene spacer. The solubilizing alkyl side groups in the central unit enabled PS1 to be readily dissolved in non-chlorinated solvents. By using 2-methyltetrahydrofuran as the processing solvent, the all-polymer solar cell (all-PSC) containing PS1 and a polymer donor PTzBI-oF in the light-harvesting layer exhibited an impressively high power conversion efficiency of 13.8%.

Binary non-fullerene-based polymer solar cells with a 430 nm thick active layer showing 15.39% efficiency and 73.38% fill factor

High hole mobility polymer and Y-series non-fullerene acceptor boost efficiency and fill factor of thick-film polymer solar cells.

Engineering donor–acceptor conjugated polymers for high-performance and fast-response organic electrochemical transistors

The donor, side chain, polymerization method, and processing solvent were systematically explored for diketopyrrolopyrrole (DPP) based donor–acceptor polymers to achieve high-performance and fast-response organic electrochemical transistors.

Theoretical Designing of Novel Donor Acceptor Type Copolymer Comprising of Thiophene

Using ab initio band structure results of three novel donor acceptor polymers (A)x PCDT, (B)x PMCT and (C)x PFTh as the input, the electronic structures and conduction properties of their periodic and aperiodic copolymer (AmBnCk)x have been investigated. The method involves using negative factor counting method based on Dean’s negative eigenvalue theorem. In this article, the quasi-one-dimensional Type II staggered copolymers comprising of thiophene units on the basis of the band alignments of the constituent homopolymers were studied. The trends in their electronic structures and conduction properties as a function of (i) block sizes (m, n, k) and (ii) arrangement of the blocks (periodic or aperiodic) in the various copolymer chains are discussed. These trends are important guidelines to the experimentalists for designing novel electrically conducting polymers with tailor made conduction properties.

Cost-Efficiency Balanced Polymer Acceptors Based on Lowly Fused Dithienopyrrolo[3, 2b]Benzothiadiazole for 16.04% Efficiency All-Polymer Solar Cells

Cost-Efficiency Balanced Polymer Acceptors Based on Lowly Fused Dithienopyrrolo[3, 2b]Benzothiadiazole for 16.04% Efficiency All-Polymer Solar Cells

Comparison of two side-chain design strategies for indacenodithienothiophene–naphthalene diimide polymer photovoltaic acceptors prepared by direct (hetero)arylation polycondensation

Two new indacenodithienothiophene–naphthalene diimide polymer acceptors PIN-1 and PIN-2 are rationally designed by two side-chain design strategies (SE-2 and SE-3) and are synthesized by the direct (hetero)arylation polycondensation (DHAP) method.

Polymerized Small‐Molecule Acceptors for High‐Performance All‐Polymer Solar Cells

AbstractAll‐polymer solar cells (all‐PSCs) have drawn tremendous research interest in recent years, due to their inherent advantages of good film formation, stable morphology, and mechanical flexibility. The most representative and most widely used n‐CP acceptor was the naphthalene diimide based D‐A copolymer N2200 before 2017, and the power conversion efficiency (PCE) of the all‐PSCs based on N2200 reached over 8% in 2016. However, the low absorption coefficient of N2200 in the near‐infrared (NIR) region limits the further increase of its PCE. In 2017, we proposed a strategy of polymerizing small‐molecule acceptors (SMAs) to construct new‐generation polymer acceptors. The polymerized SMAs (PSMAs) possess low band gap and strong absorption in the NIR region, which attracted great attention and drove the PCE of the all‐PSCs to over 15% recently. In this Minireview we explain the design strategies of the molecular structure of PSMAs and describe recent research progress. Finally, current challenges and future prospects of the PSMAs are analyzed and discussed.

Triazine and Porphyrin-Based Cross-Linked Conjugated Polymers: Protonation-Assisted Dissolution and Thermoelectric Properties

As two pivotal functional segments, triazine and porphyrin can be coupled to form a highly cross-linked conjugated polymer. Although the obtained conjugated polymers are almost insoluble in most so...

Polymerized Small-Molecule Acceptors for High-Performance All-Polymer Solar Cells.

All-polymer solar cells (all-PSCs) have drawn tremendous research interest in recent years, due to their inherent advantages of good film formation, stable morphology, and mechanical flexibility. The most representative and most widely used n-CP acceptor was the naphthalene diimide based D-A copolymer N2200 before 2017, and the power conversion efficiency (PCE) of the all-PSCs based on N2200 reached over 8% in 2016. However, the low absorption coefficient of N2200 in the near-infrared (NIR) region limits the further increase of its PCE. In 2017, we proposed a strategy of polymerizing small-molecule acceptors (SMAs) to construct new-generation polymer acceptors. The polymerized SMAs (PSMAs) possess low band gap and strong absorption in the NIR region, which attracted great attention and drove the PCE of the all-PSCs to over 15% recently. In this Minireview we explain the design strategies of the molecular structure of PSMAs and describe recent research progress. Finally, current challenges and future prospects of the PSMAs are analyzed and discussed.

Efficient, Thermally Stable, and Mechanically Robust All‐Polymer Solar Cells Consisting of the Same Benzodithiophene Unit‐Based Polymer Acceptor and Donor with High Molecular Compatibility

AbstractAll‐polymer solar cells (all‐PSCs) are a highly attractive class of photovoltaics for wearable and portable electronics due to their excellent morphological and mechanical stabilities. Recently, new types of polymer acceptors (PAs) consisting of non‐fullerene small molecule acceptors (NFSMAs) with strong light absorption have been proposed to enhance the power conversion efficiency (PCE) of all‐PSCs. However, polymerization of NFSMAs often reduces entropy of mixing in PSC blends and prevents the formation of intermixed blend domains required for efficient charge generation and morphological stability. One approach to increase compatibility in these systems is to design PAs that contain the same building blocks as their polymer donor (PD) counterparts. Here, a series of NFSMA‐based PAs [P(BDT2BOY5‐X), (X = H, F, Cl)] are reported, by copolymerizing NFSMA (Y5‐2BO) with benzodithiophene (BDT), a common donating unit in high‐performance PDs such as PBDB‐T. All‐PSC blends composed of PBDB‐T PD and P(BDT2BOY5‐X) PA show enhanced molecular compatibility, resulting in excellent morphological and electronic properties. Specifically, PBDB‐T:P(BDT2BOY5‐Cl) all‐PSC has a PCE of 11.12%, which is significantly higher than previous PBDB‐T:Y5‐2BO (7.02%) and PBDB‐T:P(NDI2OD‐T2) (6.00%) PSCs. Additionally, the increased compatibility of these all‐PSCs greatly improves their thermal stability and mechanical robustness. For example, the crack onset strain (COS) and toughness of the PBDB‐T:P(BDT2BOY5‐Cl) blend are 15.9% and 3.24 MJ m–3, respectively, in comparison to the PBDB‐T:Y5‐2BO blends at 2.21% and 0.32 MJ m–3.

Poly(2,2’-(2,5-difluoro-1,4-phenylene)dithiophene-alt-naphthalene diimide) synthesized by direct (hetero)arylation reaction for all-polymer solar cells

The weak donor-strong acceptor polymer acceptors for all-polymer solar cells (all-PSCs) have gained much less attention compared with the typical donor-strong acceptor counterparts. Direct (hetero)arylation polymerization reaction is a rising synthetic method, although most of the naphthalene diimide polymer photovoltaic acceptors have been prepared by classic Stille polymerization. A weak donor-strong acceptor polymer acceptor PNB2F has been successfully designed and synthesized by the two-step direct (hetero)arylation reaction and further applied in all-PSCs. The all-PSC device based on PNB2F and electron-donating polymer PBDB-T gained a PCE of 4.49%. The results demonstrate that direct (hetero)arylation reaction is a promising tool for building efficient polymer acceptors with convenient and low-cost synthesis ideas. • The polymer acceptor PNB2F has been successfully synthesized by a convenient two-step direct (hetero)arylation reaction. • PNB2F is a weak donor-strong acceptor polymer acceptor, which has gained much less attention compared with the typical donor-strong acceptor counterparts. • The PBDB-T: PNB2F based all-PSCs achieves a PCE of 4.49%.

Impact of the Electron Acceptor Nature on the Durability and Nanomorphological Stability of Bulk Heterojunction Active Layers for Organic Solar Cells.

A systematic study is conducted to compare the performances and stability of active layers employing a high performance electron donor (PBDB-T) combined with state-of-the-art fullerene (PC71 BM), nonfullerene (ITIC), and polymer (N2200) electron acceptors. The impact of the chemical nature of the acceptor on the durability of organic solar cells (OSCs) is elucidated by monitoring their photovoltaic performances under light exposure or dark conditions in the presence of oxygen. PC71 BM molecules exhibit a higher resistance toward oxidation compared to nonfullerene acceptors. Unencapsulated PBDB-T:PC71 BM OSCs display relatively stable performances at room temperature when stored in air for 3 months. However, when exposed to temperatures above 80°C, their active materials demix causing notable reductions in the short-circuit densities. Such detrimental demixing can also be seen for PBDB-T:ITIC active layers above 120°C. Although N2200 chains irreversibly degrade when exposed to air, thermally induced demixing does not occur in PBDB-T:N2200 active layers annealed up to 200°C. In summary, fullerene OSCs may be the best currently available choice for unencapsulated room temperature applications but if oxidation of the polymer acceptors can be avoided, all polymer active layers should enable the fabrication of highly durable OSCs with lifetimes matching the requirements for OSC commercialization.