Considering the increasing demand for high-resolution light-emitting diodes (LEDs), it is important that direct fine patterning technologies for LEDs be developed, especially for quantum-dot LEDs ...(QLEDs). Traditionally, the patterning of QLEDs relies on resin-based photolithography techniques, requiring multiple steps and causing performance deterioration. Nondestructive direct patterning may provide an easy and stepwise method to achieve fine-pixelated units in QLEDs. In this study, two isomeric tridentate cross-linkers (X8/X9) are presented and can be blended into the hole transport layer (HTL) and the emissive layer (EML) of QLEDs. Because of their photosensitivity, the in situ cross-linking process can be efficiently triggered by ultraviolet irradiation, affording high solvent resistance and nondestructive direct patterning of the layers. Red QLEDs using the cross-linked HTL demonstrate an impressive external quantum efficiency of up to 22.45%. Through lithographic patterning enabled by X9, line patterns of HTL and EML films exhibit widths as narrow as 2 and 4 μm, respectively. Leveraging the patterned HTL and EML, we show the successful fabrication of pixelated QLED devices with an area size of 3 × 3 mm2, alongside the successful production of dual-color pixelated QLED devices. These findings showcase the promising potential of direct patterning facilitated by engineered cross-linkers for the cost-effective fabrication of pixelated QLED displays.
A new triaryl-borane-BODIPY based electron acceptor (BDY) for the bulk hetero-junction solar cell is reported. The electron acceptor property of BDY was fine-tuned by introducing the triphenylamine ...moieties. The electron mobility value of BDY was found to be of the order of standard PC61BM. BHJ solar devices were fabricated using BDY as the electron acceptor and maximum PCE of 4.46% is achieved.
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•First example of triaryl-borane-BODIPY based bulk heterojunction solar cells (BHJ).•Introducing the TPA, the acceptor properties of the triaryl-borane-BODIPY is tuned.•We have fabricated different devices (conventional BHJ, Inverted BHJ).•The maximum PCE of 4.46% is achieved and there is a lot of room to improve the PCE.•This concept can be used to develop diverse TAB-BODIPY based acceptors for OPV cell.
A new X-type, structurally twisted, highly soluble TAB-BODIPY based electron acceptor (BDY) is designed and synthesized. Organic solar devices are fabricated using poly(3-hexylthiophene-2,5-diyl) (P3HT) as donor polymer and BDY as an electron acceptor. A promising power conversion efficiency of 4.46% is obtained for this new class of acceptor, which is the first-ever reported on TAB-BODIPY as a non-fullerene acceptor in organic solar cells.
C–H activation reactions have allowed us to react traditionally chemically inert bonds in molecules to develop new methods for cross-coupling reactions. This type of reactivity can be applied to ...conjugated polymer materials in an effort to improve existing synthetic difficulties including harsh reaction conditions, multiple monomer functionalization steps, and organometallic reagent waste. In this Viewpoint, we highlight some of the encouraging advances in direct arylation polymerization (DArP) as well as ongoing challenges for future improvement and utility.
An investigation for the initiation of a chain-growth polymerization, Kumada catalyst-transfer polycondensation, for the synthesis of poly(3-hexylthiophene) is described. A novel method for the ...generation of an active catalyst/initiator complex was developed utilizing the inexpensive, air stable Ni(PPh3)2Cl2 precursor to generate the active Ni(PPh3)4 catalyst in situ. Poly(3-hexylthiophene) polymerization reactions were carried out using aryl halides with various substituents on the phenyl ring as external initiators, and it was found that the type of the functional group present on the initiator plays a crucial role in the polymerization. The new method provided a more efficient way to initiate polymerization yielding polymers with higher regioregularity, larger molecular weight, and lower polydispersity than the previously reported methods.
Solution-processable n-type ladder-based polymers are highly desirable due to their potential capability to form strong π–π interactions. A series of 5 highly soluble naphthalene diimide (NDI) ...polymers are presented, differing in the degree to which they are able to form imine-bridged ladder polymer structures. Average electron mobilities as high as 0.0026 cm2 V–1 s–1, which show an electron-mobility improvement of 4 orders of magnitude following ladderization, and on/off current ratios on the order of 104 are reported for the novel material PNDI-2BocL, an alkyl-substituted poly(benzoquinolinophenanthrolinedione). The structure–property relationship of the aforementioned series of copolymers is presented and discussed as it pertains to organic field-effect transistor (OFET) performance.
The shape of the mid-IR absorption spectrum provides valuable information about the “hole” polaron coherence length in doped and undoped conjugated polymer films. In poly(3-hexylthiophene) (P3HT) ...films, the spectrum generally consists of a narrow, low-energy peak A (700–1000 cm–1) followed by a much broader, higher-energy peak B (2500–5000 cm–1). By using a theory based on the Holstein Hamiltonian for mobile holes in P3HT, the IR line-shape is successfully reproduced for several recently measured spectra recorded in doped and undoped films, confirming the association of an enhanced peak ratio (A/B) with extended polaron coherence. Emphasis is placed on the origin of components polarized along the intra- and interchain directions and their dependence on the spatial distribution of disorder as well as the position of the dopant relative to the π-stack. The model is further adapted to treat donor–acceptor copolymers where the local HOMO energy varies periodically from donor unit to acceptor unit. The calculated line shape for a diketopyrrolopyrrole-based copolymer agrees well with the recently measured spectrum.
The molecular morphology and dynamics of conjugated polymers in the bulk solid state play a significant role in determining macroscopic charge transport properties. To understand this relationship, ...molecular dynamics (MD) simulations and quantum mechanical calculations are used to evaluate local electronic properties. In this work, we investigate the importance of system and simulation parameters, such as force fields and equilibration methods, when simulating amorphous poly(3-hexylthiophene) (P3HT), a model semiconducting polymer. An assessment of MD simulations for five different published P3HT force fields is made by comparing results to experimental wide-angle X-ray scattering (WAXS) and to a broad range of quasi-elastic neutron scattering (QENS) data. Moreover, an
in silico
analysis of force field parameters reveals that atomic partial charges and torsion potentials along the backbone and side chains have the greatest impact on structure and dynamics related to charge transport mechanisms in P3HT.
An honest discussion on the strengths and limitations of molecular dynamics force fields for P3HT through neutron scattering.
A series of fully conjugated graft copolymers containing poly(3-hexylthiophene) (P3HT) side chains and a p-type carbazole-diketopyrrolopyrrole (CbzDPP) donor–acceptor backbone were synthesized via a ...graft through Suzuki polymerization. The macromonomers were formed by externally initiating P3HT growth from a boronic ester-functionalized carbazole via Kumada catalyst transfer polycondensation. Subsequently, this macromonomer was copolymerized with a DPP monomer via a graft through Suzuki polymerization to yield the final graft copolymers. The graft copolymers exhibit optical and electronic properties of both P3HT and the CbzDPP polymers independently due to the break in conjugation between the carbazole unit and P3HT chain. Moreover, these properties reflect the relative proportion of P3HT and CbzDPP polymers; shorter P3HT chain lengths lead to graft copolymers that possess more CbzDPP character and vice versa. The macromonomers were characterized by gel permeation chromatography, mass spectrometry, and UV–visible spectroscopy. The graft copolymers were further investigated using gel permeation chromatography, UV–visible spectroscopy, cyclic voltammetry, differential scanning calorimetry, and atomic force microscopy. Finally, organic field effect transistors were fabricated using the graft copolymers and compared to an analogous linear CbzDPP copolymer. Ultimately, the graft copolymers with the longest P3HT chains (ca. 75 repeat units) exhibited almost exclusively P3HT characteristics, possessing a small CbzDPP internal charge transfer (ICT) peak and only p-type conductivity (μh ∼ 6 × 10–4 cm2 V–1 s–1). Conversely, the graft copolymers with the shortest P3HT chains (ca. 10 repeat units) showed significant CbzDPP character, including a strong ICT peak and ambipolar mobilities (μh ∼ 5 × 10–3 cm2 V–1 s–1; μe ∼ 7 × 10–4 cm2 V–1 s–1).
π-Conjugated polymers are materials of interest for use in organic electronics. Within these polymers, donor–acceptor polymers are favorable for solar cell applications due to improved charge ...mobility, better absorption in the low energy region of the solar spectrum, and tunable band gaps. One of the barriers to commercializing these donor–acceptor materials is that their synthetic pathways are complex because of the alternating repeat units in the polymer. To address this, the application of cross dehydrogenative coupling (also called oxidative CH/CH cross-coupling) toward the synthesis of donor–acceptor polymers was explored. In this work, the roles of specific reagents in a one-pot gold- and silver-catalyzed cross dehydrogenative coupling and the factors that contribute to selectivity for cross-coupling rather than homo-coupling are analyzed. Based on our results, we postulate that the percentage of alternating repeat units in the final polymer is affected by the increased reactivity of the dimer that forms in the initial stages of the polymerization compared to the monomer, which ultimately may be exploited to control the ratio of electron-rich to electron-poor monomers.
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