Processable High Electron Mobility π‐Copolymers via Mesoscale Backbone Conformational Ordering

Abstract

The synthesis and experimental/theoretical characterization of a new series of electron‐transporting copolymers based on the naphthalene bis(4,8‐diamino‐1,5‐dicarboxyl)amide (NBA) building block are reported. Comonomers are designed to test the emergent effects of manipulating backbone torsional characteristics, and density functional theory (DFT) analysis reveals the key role of backbone conformation in optimizing electronic delocalization and transport. The NBA copolymer conformational and electronic properties are characterized using a broad array of molecular/macromolecular, thermal, optical, electrochemical, and charge transport techniques. All NBA copolymers exhibit strongly aggregated morphologies with significant nanoscale order. Copolymer charge transport properties are investigated in thin‐film transistors and exhibit excellent electron mobilities ranging from 0.4 to 4.5 cm2 V−1 s−1. Importantly, the electron transport efficiency correlates with the film mesoscale order, which emerges from comonomer‐dependent backbone planarity and extension. These results illuminate the key NBA building block structure–morphology–bulk property design relationships essential for processable, electronics‐applicable high‐performance polymeric semiconductors.

Thiazoloisoindigo-based ambipolar polymers for excellent balanced hole and electron mobility

“…49,50 Furthermore, in the solution state, the 0–0 vibration peak are stronger than 0–1 vibration peak, which according to the H , J -aggregation model for organic semiconductor, can be ascribed to a stronger J -type intrachain coupling. 33 It is worth noting that the 0–0/0–1 intensity ratio has changed slightly in the film state, and an increase in the intensity of the 0–1 vibrational peak was observed in the film state spectrum of P(T-TzII-T-DPP)-C12 , which may indicate a relatively increased H -type aggregation character in the film state. A similar observation was made in P(Se-TzII-T-DPP)-C12 and P(Se-TzII-T-DPP)-C20 (Fig.…”

“…3, it can be seen clearly that the trimer adopts a perfect linear coplanar conformation (both from the top view and from the side view), and has an even HOMO and LUMO orbital distribution along all of the repeating units, which is also well known to facilitate more efficient interchain coupling interaction. 33,44 Overall, theoretical calculations predict that the copolymer of T-TzII and T-DPP has an ideal coplanar molecular backbone, suitable HOMO/LUMO energy levels, long-range orbital distribution of HOMO/LUMO along the polymer chain and strong dipole–dipole interaction, all beneficial for high and balanced ambipolar charge transport.…”

“…The populations of the conformer with y 1 /y 2 /y 3 = 01 can be further confirmed to be the predominant conformer according to the equation of Boltzmann distribution. [32][33][34] To quantify torsional conformations and their relative contribution to the overall structural disorder, a planarity index (hcos 2 yi) was introduced as an empirical parameter. 35,36 We found that the combinations of TzII and thiophene (y 1 ) units, thiophene and thiophene (y 2 ) units, thiophene and DPP (y 3 ) units show high hcos 2 y 1 i, hcos 2 y 2 i, and hcos 2 y 3 i values of 0.9326, 0.8834, and 0.9272, respectively.…”

Acceptor Modulation Strategies for Improving the Electron Transport in High‐Performance Organic Field‐Effect Transistors

“…Two copolymers (P63a and P63b) based on the NBA and 2FBT moieties with different F atoms (0 and 2F) were synthesized. [ 152 ] After introduction of F atoms into the benzothiadiazole, the HOMO energy level of P63b was lowered to −5.92eV, which was 0.35 lower than that of P63a. GIXRD characterization indicated that the fluoropolymer P63b adopted both edge‐on and face‐on orientations, whereas P63a only formed a face‐on orientation.…”

Boosting photoprogramming performance of molecular-switch-embedded organic transistors via structural optimization of polymer semiconductors

“…Recent researches on donor-acceptor copolymer semiconductors reporting high mobility have shown that the degree of crystallinity does not directly correlate with the performance of polymer semiconductors. [31][32][33][34] This means that even in a polymer semiconductor with low crystallinity, efficient charge transport can be realized when sufficient tie chains are linked between small-localized aggregations. Utilizing a semi-paracrystalline polymer semiconductor in a photochromic hybrid system can simultaneously manifest high mobility and photoprogramming characteristics, which were considered before as a trade-off in previous polymer semiconductor/DAE hybrid systems.…”