One of the major challenges confronting organic electronics is the development of high-mobility semiconducting materials, especially n-channel and ambipolar semiconductors. Solution-processable semiconducting polymers have attracted much attention because of their tunable properties and their suitability for the fabrication of large-scale devices. Aza substitution has proven effective in electron-transport small-molecule semiconductors; however, high-performance polymeric semiconductors prepared by aza substitution are still lacking. We started with a computational screening procedure to introduce nitrogen atoms into isoindigo-based polymers and then proceeded with the synthesis and fabrication of field-effect transistors. The resulting 7,7′-diazaisoindigo-based polymers exhibit extensive π conjugation and high crystallinity with hole mobilities exceeding 7 cm 2 V −1 s −1 with bottom-gate/bottom-contact configuration and ambipolar transport properties with top-gate/bottom-contact configuration in air. These properties make diazaisoindigo a promising building block for polymeric semiconductors.

We develop two donor−acceptor copolymers based on a fluorinated dithienylethene building block, namely PNFDTE1 and PNFDTE2, in which naphthalenediimide (NDI) acts as an acceptor unit. Thermogravimetric analysis displayed both copolymers having good thermal stability with high decomposition temperatures over 400 °C. Broad absorption spectra were observed in the UV−vis−NIR region, with the absorption maxima being 720 and 724 nm for PNFDTE1 and PNFDTE2, respectively. Cyclic voltammetry tests exhibited deep-lying lowest unoccupied molecular orbital energy levels of ca. −4.0 eV. Twodimensional grazing incidence X-ray diffraction patterns showed that different packing modes for two polymers result in the variation in charge transport properties. Backbone fluorination effectively decreases electron injection barrier, thereby facilitating electron mobility. An impressive electron mobility of 3.20 cm 2 V −1 s −1 was achieved in air for PNFDTE1-based polymer field-effect transistors fabricated on the poly(ethylene terephthalate) substrate. The mobility value is almost the highest for NDI-containing polymers on the flexible substrate. This work provides a guideline for design and synthesis of fluorinated semiconductors that enables control of chargetransport polarity.

Designing materials with appropriate crystal and electronic structures to enhance ionic and electronic transport simultaneously are highly desirable for both electrochromic and electrochemical energy storage devices. It remains a great challenge to simultaneously meet these requirements. Here, a Nb18W16O93 nanomaterial is successfully synthesized with superstructure motifs and uniform self‐supported electrochromic films are prepared on a transparent conductive substrate. The results show that the films can effectively accommodate lithium ions and facilitate intercalation–deintercalation on transparent fluorine‐doped tin oxide (FTO) substrates at high current density. Mechanistic insights into the excellent electrochromic and rechargeable energy storage properties are provided by density functional theory (DFT) calculations. Specifically, the Nb18W16O93 film displays a large optical modulation (up to 93% at 633 nm and 89% at 1200 nm), high coloration efficiency (105.6 cm2 C−1), high energy storage capacity (151.4 mAh g−1 at 2 A g−1), excellent rate capability, and long‐term electrochemical stability (6000 cycles). As a demonstration of its application, an energy storage indicator is illustrated and a complementary electrochromic energy storage smart window is fabricated based on the Nb18W16O93 film. The results demonstrate that the Nb18W16O93 nanomaterial has a promising application in the field of high‐performance electrochromic and energy storage devices.

Crucial to the development of polymeric semiconductors has been the establishment of structure-property correlations to achieve high-mobility and versatile devices. [2] Despite the continuing improvement of carrier mobilities, a clear understanding of charge transport mechanisms and the relationship between device function and molecular structure are yet to be fully explored. Thanks to the thirdgeneration donor-acceptor (D-A) alternating conjugated copolymers, tunable comonomers are able to be incorporated into the backbone, evolving in the diversity and complexity to deeply investigate the influencing factors. [3] Coplanarity, π-conjugation, linearity, symmetry, frontier molecular orbital (FMO) energy, heteroatom effect, molecular weight, and density of side chains, to name but a few, are usually deemed critical in the structural and conformational control for rational design of conjugated polymers. When attempting to gain insight into these sophisticated factors, one might select a state-of-the-art building block and adjust the other moiety to fine-tune electronic and solid-state structures. A delicate compromise between such factors is also needed to achieve the optimal device performance. [4] Exploring new structures to boost device performance has always been the motivation of synthetic scientists. [1c,h,5] During the past few years, bislactam or bisimide has emerged as electron-withdrawing building blocks for high-performance semiconductors. For example, field-effect transistors of diketopyrrolopyrrole-, isoindigo-, and naphthalenediimide-based polymeric semiconductors exhibit mobilities of 1-10 cm 2 V −1 s −1 , which are comparable to inorganic counterparts. [1c,d] The incorporation of bislactam or bisimide provides three major advantages: (a) the electron deficient nature of these functional groups lowers the FMO energy levels to stabilize injected charge carriers and enhances stacking interactions between π-orbitals by depleting electron density and subsequently relieving electrostatic repulsion; [6] (b) the presence of intramolecular throughspace interactions minimizes dihedral torsions and promotes backbone coplanarity; [1c] (c) readily introduced side chains can not only tune the polymer aggregation tendency but also ensure solution processability. [3b] Among these bislactam-orTo establish a structure-property relationship between polymer backbone structures and field-effect transistor performance has emerged as a new topic in organic electronics. The tunability and diversity of organic semiconductors provide the feasibility of controlling the electrical properties. Herein the characterization of thienothiophene-, dithiophenylethene-, biselenophene-, and diselenophenylethene-containing azaisoindigo copolymers is presented. As suggested by both theoretical calculations and experimental results, backbone electronic structure and linearity, density of side chains, aggregation, and thin film microstructure are involved in the differences in optical and electrical properties of these polymers. As...

Two highly planar cross-conjugated polymers with multiple conformational locks were designed and synthesized, and their charge transport properties were investigated.

The exploration of unipolar n-channel semiconductors plays an important role in the advance of organic complementary inverters and complementary logic circuits. Based on the conventional donor–acceptor type conjugated copolymers, the...

A novel building block (VDTOI) was designed and synthesized. VDTOI-based copolymers exhibit a high mobility of 0.35 cm2 V−1 s−1.

Herein, we report a series of tetrafluoroethylene (TFE)-containing semiconducting polymers 80, 70, 60, and 0), in which the TFE segments were first introduced into polymeric main chains as flexible π-nonconjugated nodes, and its fully conjugated analogue PNBDO-FDTE100. Our results indicate that the TFE segment is quite compatible with the NBDO-alt-FDTE conjugated matrix system. The HOMO/LUMO energy levels (approximately −6.0/−4.0 eV) and optical band gaps (1.28 eV) remain almost the same in the polymers with the TFE content varying from 0% to 40%. The polymers PNBDO-FDTEm (m = 90, 80, 70, and 60) have similar highly ordered molecular packing with close π−π stacking in a thin film as PNBDO-FDTE100 does, implying that the TFE segments exert no clear negative influences on the molecular packing of these polymers either. PNBDO-FDTE100 exhibited a much high electron mobility (μ e ) of 7.43 cm 2 V −1 s −1 , while PNBDO-FDTE90 and PNBDO-FDTE80 also showed impressively high μ e values of 7.25 and 6.00 cm 2 V −1 s −1 , respectively. However, PNBDO-FDTEm (m = 70, 60, and 0) afforded a μ e as low as 0.182 cm 2 V −1 s −1 . We attributed this to the transition of the carrier transport mode caused by the increase in the number of π-nonconjugated nodes.