The future of organic photovoltaics Mazzio, Katherine A; Luscombe, Christine K
Chemical Society reviews,
01/2015, Letnik:
44, Številka:
1
Journal Article
Recenzirano
Increasing global demand for energy, along with dwindling fossil fuel resources and a better understanding of the hidden costs associated with these energy sources, have spurred substantial ...political, academic, and industrial interest in alternative energy resources. Photovoltaics based on organic semiconductors have emerged as promising low-cost alternatives for electricity generation that relies on sunlight. In this tutorial review we discuss the relevance of these organic photovoltaics beginning with some of the economic drivers for these technologies. We then examine the basic properties of these devices, including operation and materials requirements, in addition to presenting the development of the field from a historical perspective. Potential future directions are also briefly discussed. This tutorial review is intended to be an essential overview of the progress of the field, in addition to aiding in the discussion of the future of OPV technologies.
This work summarizes the development of organic photovoltaics, including their economic motivation, device operation, and materials.
Organic photovoltaic cells made with semiconducting polymers remain one of the most promising technologies for low-cost solar energy due to their compatibility with roll-to-roll printing techniques. ...The development of new light-absorbing polymers has driven tremendous advances in the power conversion efficiency of these devices. In particular, the use of alternating electron rich (donor) and electron poor (acceptor) segments along the polymer backbone can produce low optical bandgap materials that capture more of the solar spectrum. As a result, power conversion efficiencies over 10% are increasingly common for this technology. This review summarizes the recent advances in donor-acceptor polymer design and synthesis, highlighting the structural features that are key to providing high efficiency, scalable and stable devices.
Expanding the toolbox of the biology and electronics mutual conjunction is a primary aim of bioelectronics. The organic electrochemical transistor (OECT) has undeniably become a predominant device ...for mixed conduction materials, offering impressive transconduction properties alongside a relatively simple device architecture. In this review, we focus on the discussion of recent material developments in the area of mixed conductors for bioelectronic applications by means of thorough structure–property investigation and analysis of current challenges. Fundamental operation principles of the OECT are revisited, and characterization methods are highlighted. Current bioelectronic applications of organic mixed ionic–electronic conductors (OMIECs) are underlined. Challenges in the performance and operational stability of OECT channel materials as well as potential strategies for mitigating them, are discussed. This is further expanded to sketch a synopsis of the history of mixed conduction materials for both p- and n-type channel operation, detailing the synthetic challenges and milestones which have been overcome to frequently produce higher performing OECT devices. The cumulative work of multiple research groups is summarized, and synthetic design strategies are extracted to present a series of design principles that can be utilized to drive figure-of-merit performance values even further for future OMIEC materials.
Owing to their versatile (opto)electronic properties, conjugated polymers have found application in several organic electronic devices. Cross‐coupling reactions such as Stille, Suzuki, Kumada ...couplings, and direct arylation reactions have proved to be effective for their synthesis. More atom‐efficient oxidative direct arylation polymerization has also been reported for making homopolymers. However, growing interest toward donor‐acceptor polymers has led to the recent emergence of cross‐dehydrogenative coupling (CDC) polymerization to synthesize alternating copolymers without any prefunctionalization of monomers. Metal‐catalyzed cross‐coupling of two simple arenes via double C−H activation, or of an arene with an alkene via oxidative Heck‐type reaction have been used so far for CDC polymerization. In this article, we discuss the development of CDC polymerization protocols along with the relevant small molecule CDC reactions for an improved understanding of these reactions.
Cross‐dehydrogenative coupling (CDC) via C−H activation is the latest addition in the repertoire of synthetic strategies towards conjugated polymers. This article captures the development of this polymerization strategy in the light of background small molecule reactions and highlights how its approach is greener than the previous methods. Arene–arene and arene–alkene couplings via transition metal catalysts have been explored for CDC polymerization.
Simple and efficient methods are a key consideration for small molecule and polymer syntheses. Direct arylation polymerization (DArP) is of increasing interest for preparing conjugated polymers as an ...effective approach compared to conventional cross-coupling polymerizations. As DArP sees broader utilization, advancements are needed to access materials with improved properties and different monomer structures and to improve the scalability of conjugated polymer synthesis. Presented herein are considerations for developing new methods of conjugated polymer synthesis from small molecule transformations, exploring how DArP has successfully used this approach, and presenting how emerging polymerization methodologies are developing similarly. While it is common to adapt small molecule methods to polymerizations, we demonstrate the ways in which information gained from studying polymerizations can inform and inspire greater advancements in small molecule transformations. This circular approach to organic synthetic method development underlines the value of collaboration between small molecule and polymer-based synthetic research groups.
We study poly(3-{2-(2-methoxyethoxy)ethoxymethyl}thiophene-2,5-diyl) (P3MEEMT), a new polythiophene derivative with ethylene glycol-based side chains, as a promising semiconducting polymer ...for accumulation-mode organic electrochemical transistors (OECTs) with figures of merit comparable to those of state-of-the-art materials. By characterizing the OECT performance of P3MEEMT transistors as a function of the anion, we find that large hydrophobic anions lower the threshold voltage. We find that, compared to poly(3-hexylthiophene-2,5-diyl) (P3HT), P3MEEMT has faster anion injection rates, which we attribute to the hydration of the P3MEEMT crystal lattice. We study P3MEEMT-based OECT and organic field-effect transistor (OFET) performance as a function of film crystallinity and show that changing the crystallinity of the polymer by thermal annealing increases the OFET mobility yet decreases the OECT mobility. We attribute this difference to the fact that, unlike OFETs, OECTs operate in aqueous environments. To probe how hydration affects the operation of OECTs, we investigate the role of water in electrochemical doping using electrochemical quartz microbalance (EQCM) gravimetry. We find that steady-state hydration and hydration dynamics under electrochemical bias differ dramatically between the crystalline and amorphous P3MEEMT films. These results suggest that the presence of water reduces the electronic connectivity between the crystalline regions of P3MEEMT, thus lowering the mobility in solution. Overall, our study highlights the importance of the role of polymer hydration and nanoscale morphology in elucidating design principles for OECT operation.
Plastic pollution is a threat to marine life with long term impacts to ecosystems and organisms in the sea. In this study, we quantified the presence of microparticles in wild populations of Pacific ...oysters (Crassostrea gigas) from the Salish Sea, Washington State. Examination under a dissecting microscope revealed 63% of oysters contained microparticles (~1.75 microparticles per oyster) and microfibers were the dominant type of particles. Using Raman microspectroscopy (RMS) and Fourier transform infrared microspectroscopy (μ-FTIR) we found that only ~2% of these microparticles were synthetic and included polymers such as polystyrene, polyethylene, polypropylene, poly(bisphenol A carbonate), rayon, and polyacrylate. It is important to note that of the 447 microparticles analyzed with RMS, 41% showed fluorescence interference, impeding the determination of their identification. The remaining microparticles were cellulose derivatives, shell fragments, biological or proteinaceous material, salts, minerals, and gypsum. Fourier transform infrared spectroscopy equipped with a diamond attenuated total reflectance accessory (ATR-FTIR) showed the presence of sorbitan derivatives in all samples examined (n = 213). These findings provide the first baseline for microplastic and other particles in oysters from the west coast of the United States integrating results from ATR-FTIR, μ-FTIR, and RMS, in addition to visual sorting. These results suggest there is low retention of plastic particles in Pacific oysters from the Salish Sea, but further research is needed to determine the composition of microparticles with fluorescence interference.
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•Microplastics in oysters were found in 5 of 10 sites in the Salish Sea, Washington.•Only ~2% of the microparticles were identified as microplastics by RMS and FTIR.•Sorbitan derivatives, polyamide resins, cellulose, and minerals were also present.•Microfibers were observed but were not confirmed as plastic or polymeric with RMS.
Conjugated polymers (CPs) are widely used in various domains of organic electronics. However, the performance of organic electronic devices can be variable due to the lack of precise predictive ...control over the polymer microstructure. While the chemical structure of CPs is important, CP microstructure also plays an important role in determining the charge-transport, optical and mechanical properties suitable for a target device. Understanding the interplay between CP microstructure and the resulting properties, as well as predicting and targeting specific polymer morphologies, would allow current comprehension of organic electronic device performance to be improved and potentially enable more facile device optimization and fabrication. In this Feature Article, we highlight the importance of investigating CP microstructure, discuss previous developments in the field, and provide an overview of the key aspects of the CP microstructure-property relationship, carried out in our group over recent years.
Conjugated polymer (CP) microstructure plays a crucial role in determining the characteristics of a target device. Here, we provide an overview of the key aspects of the CP microstructure-property relationship carried out in our group.
A series of alkyl-substituted indacenodithiophene (alkyl-IDT) semiconducting donor–acceptor polymers were designed by DFT to have varying degrees of backbone planarity and synthesized via direct ...arylation polymerization (DArP). These polymers exhibit weak intermolecular interactions, a glass transition temperature (T g) below room temperature, and low degrees of crystallinity from XRD measurements. Despite this, the field-effect mobilities (μ) of these polymers are relatively high (0.06–0.20 cm2 V–1 s–1) with mobility increasing with increasing backbone planarity. Because of the weak intermolecular interactions, the polymers exhibit low elastic moduli (E f) of less than 450 MPa. The polymer with the most twisted backbone exhibits high ductility with a crack-onset strain (CoS) over 100%. These structure–property relationship studies provide useful guidelines for designing semiconducting polymers with high mobility, low stiffness, and high ductility enabling applications in stretchable electronics.
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