skip to main content


Title: Copolymers for electronic, optical, and sensing applications with engineered physical properties
Electronic and optoelectronic devices often require multifunctional properties combined with conductivity that are not achieved from a single species of molecules. The capability to tune chain length, shape, and physicochemical characteristics of conductive copolymers provides substantial benefits for a wide range of scientific areas that require unique and engineered optical, electrical, or optoelectronic properties. Although efforts have been made to develop synthetic routes to realize such promising copolymers, an understanding of the process–structure–property relationship of the synthesis methods needs to be further enhanced. In addition, since traditional methods are often limited to achieving pinhole-free, large-area coverage, and conformal coating of copolymer films with thickness controllability, unconventional synthetic strategies to address these issues need to be established. This Perspective article intends to enhance knowledge on the process–structure–property relationship of functional copolymers by providing the definition of copolymers, polymerization mechanisms, and a comparison of traditional and emerging synthetic methods with reaction parameters and tuned physical properties. In parallel, practical applications featuring the desired copolymers in electronic, optical, and sensing devices are showcased. Last, a pathway toward further advancement of unique copolymers for next-generation device applications is discussed.  more » « less
Award ID(s):
2207302
PAR ID:
10451165
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Applied Physics Letters
Volume:
123
Issue:
5
ISSN:
0003-6951
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Non‐conjugated pendant electroactive polymers (NCPEPs) are an emerging class of polymers that offer the potential of combining the desirable optoelectronic properties of conjugated polymers with the superior synthetic methodologies and stability of traditional non‐conjugated polymers. Despite an increasing number of studies focused on NCPEPs, particularly on understanding fundamental structure‐property relationships, no attempts have been made to provide an overview on established relationships to date. This review showcases selected reports on NCPEP homopolymers and copolymers that demonstrate how optical, electronic, and physical properties of the polymers are affected by tuning of key structural variables such as the chemical structure of the polymer backbone, molecular weight, tacticity, spacer length, the nature of the pendant group, and in the case of copolymers the ratios between different comonomers and between individual polymer blocks. Correlation of structural features with improvedπ‐stacking and enhanced charge carrier mobility serve as the primary figures of merit in evaluating impact on NCPEP properties. While this review is not intended to serve as a comprehensive summary of all reports on tuning of structural parameters in NCPEPs, it highlights relevant established structure‐property relationships that can serve as a guideline for more targeted design of novel NCPEPs in the future.

     
    more » « less
  2. Abstract

    Donor–acceptor (D–A)‐conjugated polymers have achieved promising performance metrics in numerous optoelectronic applications that continue to motivate studying structure–property relationships and discovering new materials. Here, the materials toolbox is expanded by synthesizing D–A copolymers where 1,4‐dihydropyrrolo[3,2‐b]pyrrole (DHPP) is directly incorporated into the main chain of D–A copolymers for the first time via direct heteroarylation polymerization. Notably, the synthetic complexity of DHPP‐containing polymers coupled with thieno[3,2‐b]pyrrole‐4,6‐dione (TPD) or 3,6‐bis(2‐thienyl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (Th2DPP) comonomers is calculated to be lower compared to many common conjugated polymers synthesized via direct arylation. The electron‐rich nature of DHPPs when coupled with TPD or DPP enables optoelectronic properties to be manipulated, evident by measuring distinctly different absorbance and redox properties. Additionally, these D–A copolymers demonstrate their potential in organic electronic applications, such as electrochromics and organic photovoltaics. The reported DHPP‐alt‐Th2DPP copolymer is the first DHPP‐based colored‐to‐transmissive electrochrome and achieves power conversion efficiencies of ~2.5% when incorporated into bulk heterojunction solar cells. Overall, the synthetic accessibility of DHPP monomers and their propensity to participate in robust polymerizations highlights the value of establishing structure–property relationships of an underutilized scaffold. These fundamental attributes serve to inform and advance efforts in the development of DHPP‐containing copolymers for various applications.

     
    more » « less
  3. Conjugated copolymers containing electron donor and acceptor units in their main chain have emerged as promising materials for organic electronic devices due to their tunable optoelectronic properties. Herein, we describe the use of direct arylation polymerization to create a series of fully π-conjugated copolymers containing the highly tailorable purine scaffold as a key design element. To create efficient coupling sites, dihalopurines are flanked by alkylthiophenes to create a monomer that is readily copolymerized with a variety of conjugated comonomers, ranging from electron-donating 3,4-dihydro-2 H -thieno[3,4- b ][1,4]dioxepine to electron-accepting 4,7-bis(5-bromo-3-hexylthiophen-2-yl)benzo[ c ][1,2,5]thiadiazole. The comonomer choice and electronic nature of the purine scaffold allow the photophysical properties of the purine-containing copolymers to be widely varied, with optical bandgaps ranging from 1.96–2.46 eV, and photoluminescent quantum yields as high as ϕ = 0.61. Frontier orbital energy levels determined for the various copolymers using density functional theory tight binding calculations track with experimental results, and the geometric structures of the alkylthiophene-flanked purine monomer and its copolymer are found to be nearly planar. The utility of direct arylation polymerization and intrinsic tailorability of the purine scaffold highlight the potential of these fully conjugated polymers to establish structure–property relationships based on connectivity pattern and comonomer type, which may broadly inform efforts to advance purine-containing conjugated copolymers for various applications. 
    more » « less
  4. The versatility of early transition metal chalcogenide nanomaterials, including chalcogenide perovskites, has attracted enormous attention for a variety of applications, such as photovoltaics, photocatalysis, and optoelectronic devices. These nanomaterials exhibit unique electronic and optical properties, allowing for a broad range of applications, depending on their chemical composition and crystal structure. However, solution-phase synthesis of early transition metal chalcogenide nanocrystals is challenging due, in part, to their high crystallization energy and oxophilicity. In this feature article, we explore various synthetic routes reported for inorganic ternary and binary sulfide and selenide nanomaterials that include transition metals from groups 3, 4, and 5. By systematically comparing different synthetic approaches, we identify trends and insights into the chemistry of these chalcogenide nanomaterials. 
    more » « less
  5. Abstract

    Intercalation in few‐layer (2D) materials is a rapidly growing area of research to develop next‐generation energy‐storage and optoelectronic devices, including batteries, sensors, transistors, and electrically tunable displays. Identifying fundamental differences between intercalation in bulk and 2D materials will play a key role in developing functional devices. Herein, advances in few‐layer intercalation are addressed in the historical context of bulk intercalation. First, synthesis methods and structural properties are discussed, emphasizing electrochemical techniques, the mechanism of intercalation, and the formation of a solid‐electrolyte interphase. To address fundamental differences between bulk and 2D materials, scaling relationships describe how intercalation kinetics, structure, and electronic and optical properties depend on material thickness and lateral dimension. Here, diffusion rates, pseudocapacity, limits of staging, and electronic structure are compared for bulk and 2D materials. Next, the optoelectronic properties are summarized, focusing on charge transfer, conductivity, and electronic structure. For energy devices, opportunities also emerge to design van der Waals heterostructures with high capacities and excellent cycling performance. Initial studies of heterostructured electrodes are compared to state‐of‐the‐art battery materials. Finally, challenges and opportunities are presented for 2D materials in energy and optoelectronic applications, along with promising research directions in synthesis and characterization to engineer 2D materials for superior devices.

     
    more » « less