Narrow-Band-Gap Conjugated Polymers Based on 2,7-Dioctyl-Substituted Dibenzo[a,c]phenazine Derivatives for Polymer Solar Cells

Syntheses of novel fluorinated dibenzo[a,c]phenazine comprising polymers for electrochromic device applications

In this study, five novel fluorinated dibenzo[a,c]phenazine comprising polymers were synthesized and characterized for electrochromic device applications.

A Quinoxaline-Based D-A Copolymer Donor Achieving 17.62% Efficiency of Organic Solar Cells

Side-chain engineering has been an effective strategy in tuning electronic energy levels, intermolecular interaction, and aggregation morphology of organic photovoltaic materials, which is very important for improving the power conversion efficiency (PCE) of organic solar cells (OSCs). In this work, two D-A copolymers, PBQ5 and PBQ6, are designed and synthesized based on bithienyl-benzodithiophene (BDTT) as the donor (D) unit, difluoroquinoxaline (DFQ) with different side chains as the acceptor (A) unit, and thiophene as the π-bridges. PBQ6 with two alkyl-substituted fluorothiophene side chains on the DFQ units possesses redshifted absorption, stronger intermolecular interaction, and higher hole mobility than PBQ5 with two alkyl side chains on the DFQ units. The blend film of the PBQ6 donor with the Y6 acceptor shows higher and balanced hole/electron mobilities, less charge carrier recombination, and more favorable aggregation morphology. Therefore, the OSC based on PBQ6:Y6 achieves a PCE as high as 17.62% with a high fill factor of 77.91%, which is significantly higher than the PCE (15.55%) of the PBQ5:Y6-based OSC. The PCE of 17.62% is by far one of the highest efficiencies for the binary OSCs with polymer donor and Y6 acceptor.

Facile Synthesis of the O-Functionalized Ladder-Type Dipyran Building Block and Its Application in Polymer Solar Cells

A new centrosymmetrical dipyran unit (DTDP) is successfully prepared by means of an efficient and universal way, and a series of PDTDP polymers have been prepared so as to assess their potential application in organic photovoltaic. The function of pyran moiety is not merely limited to tune the electron-donating roles and energy levels but it also contributes to solubility improvement. Interestingly, all pyran-based polymers displayed wide absorption ranging from 350 to 780 nm, but varied aggregation phenomena are observed. Furthermore, the quantum chemistry calculations for dimers, morphology study and grazing-incidence wide-angle X-ray scattering analysis for blend films have been utilized to understand the variations at photovoltaic performances. Finally, PDTDP-4 achieved the highest power conversion efficiency of 7.26% ( V_oc = 0.72 V, FF = 0.66, and J_sc = 15.30 mA/cm²), demonstrating promising usage for high-efficiency polymer donors in polymer solar cells. In all, not only a promising dipyran building block is provided by this study, more dipyran derivatives and polymers could be prepared via this facile synthetic route.

High-Performance Organic Photodetectors from a High-Bandgap Indacenodithiophene-Based π-Conjugated Donor-Acceptor Polymer

A conjugated donor-acceptor polymer, poly[4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-2,7-diyl- alt-5-(2-ethylhexyl)-4 H-thieno[3,4- c]pyrrole-4,6(5 H)-dione-1,3-diyl] (PIDT-TPD), is blended with the fullerene derivative [6,6]phenyl-C61-butyric acid methyl ester (PC₆₁BM) for the fabrication of thin and solution-processed organic photodetectors (OPDs). Systematic screening of the concentration ratio of the blend and the molecular weight of the polymer is performed to optimize the active layer morphology and the OPD performance. The device comprising a medium molecular weight polymer (27.0 kg/mol) in a PIDT-TPD:PC₆₁BM 1:1 ratio exhibits an external quantum efficiency of 52% at 610 nm, a dark current density of 1 nA/cm², a detectivity of 1.44 × 10¹³ Jones, and a maximum 3 dB cutoff frequency of 100 kHz at -5 V bias. These results are remarkable among the state-of-the-art red photodetectors based on conjugated polymers. As such, this work presents a functional organic active material for high-speed OPDs with a linear photoresponse at different light intensities.

Wide Band Gap Polymer Based on Indacenodithiophene and Acenaphthoquinoxaline for Efficient Polymer Solar Cells Application

A new wide band gap polymer PIDT-AQx with indacenodithiophene (IDT) as the electron-rich unit and acenaphthoquinoxaline (AQx) as the electron-deficient unit has been designed and synthesized. The optical band gap of PIDT-AQx was 1.81 eV with a HOMO energy level of -5.13 eV. Polymer solar cells with the blend of PIDT-AQx/PC71BM as the active layer achieved a power conversion efficiency (PCE) of 4.56%, with an open-circuit voltage (Voc) of 0.84 V, a current density (Jsc) of 9.88 mA cm-2, and a fill factor (FF) of 55% without any solvent additives and pre- or post-treatments. The photovoltaic performance of PIDT-AQx could be slightly improved with a PCE up to 4.78% after thermal annealing due to enhanced Jsc. The results indicate that acenaphthoquinoxaline is a promising building block for developing conjugated polymers for efficient solar cells application.

Composition-dependent nanoelectronics of amido-phenazines: non-volatile RRAM and WORM memory devices

A metal-free three component cyclization reaction with amidation is devised for direct synthesis of DFT-designed amido-phenazine derivative bearing noncovalent gluing interactions to fabricate organic nanomaterials. Composition-dependent organic nanoelectronics for nonvolatile memory devices are discovered using mixed phenazine-stearic acid (SA) nanomaterials. We discovered simultaneous two different types of nonmagnetic and non-moisture sensitive switching resistance properties of fabricated devices utilizing mixed organic nanomaterials: (a) sample-1(8:SA = 1:3) is initially off, turning on at a threshold, but it does not turn off again with the application of any voltage, and (b) sample-2 (8:SA = 3:1) is initially off, turning on at a sharp threshold and off again by reversing the polarity. No negative differential resistance is observed in either type. These samples have different device implementations: sample-1 is attractive for write-once-read-many-times memory devices, such as novel non-editable database, archival memory, electronic voting, radio frequency identification, sample-2 is useful for resistive-switching random access memory application.

Quinoxaline-based conjugated polymers for polymer solar cells

Recent developments of quinoxaline-based conjugated polymers for polymer solar cells are reviewed.

A new fluoropyrido[3,4-b]pyrazine based polymer for efficient photovoltaics

Using a fluoropyrido[3,4-b]pyrazine based 2D-conjugated polymer as an electron donor in polymer solar cells, a power conversion efficiency of 6.2% is obtained, which is the highest PCE among the PP-based polymers reported to date.

Novel electroluminescent donor–acceptors based on dibenzo[a,c]phenazine as hole-transporting materials for organic electronics

Novel yellow-green fluorescent 3,6,11-trisubstitued-dibenzo[a,c]phenazine derivatives were synthesized via a Buchwald–Hartwig palladium-catalyzed C–N amination reaction for the hole-transporting materials.

The optoelectronic properties of organic materials based on triphenylamine that are relevant to organic solar photovoltaic cells

A triphenylamine compound bridged with a pyrazine derivative was characterized theoretically using DFT and TD-DFT as a promising acceptor in BHJs.

A Novel Alkylated Indacenodithieno[3,2-b]thiophene-Based Polymer for High-Performance Field-Effect Transistors

A novel rigid donor monomer, indacenodithieno[3,2-b]thiophene (IDTT), containing linear alkyl chains, is reported. Its copolymer with benzothiadiazole is an excellent p-type semiconductor, affording a mobility of 6.6 cm(2) V(-1) s(-1) in top-gated field-effect transistors with pentafluorobenzenethiol-modified Au electrodes. Electrode treatment with solution-deposited copper(I) thiocyanate (CuSCN) has a beneficial hole-injection/electron-blocking effect, further enhancing the mobility to 8.7 cm(2) V(-1) s(-1) .

Enhancing the photovoltaic properties of low bandgap terpolymers based on benzodithiophene and phenanthrophenazine by introducing different second acceptor units

Two D–A type random terpolymers PBDTT-PPzIID and PBDTT-PPzDPP were synthesized by copolymerizing a donor and two acceptor units. The PBDTT-PPzDPP-based device shown a PCE of 5.91%.

Medium bandgap copolymers based on carbazole and quinoxaline exceeding 1.0 V open-circuit voltages

Given the desire for superior VOC values in PSCs, we have designed and synthesized a series of ‘medium bandgap’ donor–acceptor (D–A) copolymers containing carbazole (Cz) and quinoxaline (Qx) (PCzDT-Qx, PCzDT-fQx, and PCzDT-ffQx).

A new multi-functional conjugated polymer for use in high-performance bulk heterojunction solar cells

We report a new multi-functional copolymer, PDTP-DTBDT, containing DTP and DTBDT units. Surprisingly, the introduction of novel DTP and DTBDT units brings not only superior charge transfer properites but also charge transport characteristics for efficient bulk heterojunction solar cells.

Donor–acceptor conjugated polymers based on cyclic imide substituted quinoxaline or dibenzo[a,c]phenazine for polymer solar cells

A series of donor–acceptor type of conjugated polymers based on cyclic imide substituted quinoxaline or dibenzo[a,c]phenazine were synthesized, where the copolymers comprising dibenzo[a,c]phenazine showed much higher photovoltaic performances.

The side chain effect on difluoro-substituted dibenzo[a,c]phenazine based conjugated polymers as donor materials for high efficiency polymer solar cells

Conjugated polymers with difluoro-substituted dibenzo[a,c]phenazine as the acceptor unit and benzodithiophene derivatives as the donor unit were prepared and used for polymer solar cells.

Supramolecular electron donor–acceptor complexes formed by perylene diimide derivative and conjugated phenazines

The nanostructure and binding mode of the perylene diimide–phenazine complex can be modulated by the phenazine derivative substituents.