Stepwise heating in Stille polycondensation toward no batch-to-batch variations in polymer solar cell performance

For a given ??-conjugated polymer, the batch-to-batch variations in molecular weight (Mw) and polydispersity index (??) can lead to inconsistent process-dependent material properties and consequent performance variations in the device application. Using a stepwise-heating protocol in the Stille polycondensation in conjunction with optimized processing, we obtained an ultrahigh-quality PTB7 polymer having high Mw and very narrow ??. The resulting ultrahigh-quality polymer-based solar cells demonstrate up to 9.97% power conversion efficiencies (PCEs), which is over 24% enhancement from the control devices fabricated with commercially available PTB7. Moreover, we observe almost negligible batch-to-batch variations in the overall PCE values from ultrahigh-quality polymer-based devices. The proposed stepwise polymerization demonstrates a facile and effective strategy for synthesizing high-quality semiconducting polymers that can significantly improve device yield in polymer-based solar cells, an important factor for the commercialization of organic solar cells, by mitigating device-to-device variations

Analysis of Utilization of Biological Resources Using Text Mining Based on Freshwater Biodiversity Information Platform

The Nagoya Protocol on access to genetic resources and fair and equitable sharing of benefits arising from their utilization in the convention on biological diversity entered into force on October 12, 2014. Accordingly, attention toward securing the sovereignty and discovering the utilization value of biological resources has been increasing to secure national competitiveness. We are developing a freshwater biodiversity information platform for the systematic conservation and industrialization of freshwater biodiversity in South Korea. The platform comprises an integrated management system of freshwater bioresources for systematic registration and management of freshwater biodiversity information based on databases; a management system of storage for managing freshwater biological specimen; a utilization information system that manages efficacy, experimental method, and activity produced by the Nakdonggang National Institute of Biological Resources and external big data such as literature and patent; and a freshwater bioresources culture collection for preservation, ordering and deposition of biological resources. These systems are connected organically. Text mining, one of the big data technologies, helps to determine the utility of biological resources through comprehensive analysis. We tried to establish utilization foundations by predicting the usability of biological resources through systematic collection, processing, and analyzing external data, such as abstract, in order to support industrialization of national freshwater bioresources. Through text mining, we constructed a literature-based corpus and preprocessed the corpus with lowercase conversion and removal of stop word. Then, a word cloud was created and statistical analysis was performed. As a result, genes and diseases associated with specific biological resources have been identified. In this study, through a comprehensive analysis of species, genes, and disease information using text mining, we were able to determine the utilization value of biological resources. This study will help the freshwater biodiversity researchers by adding a function for utilization analysis in the utilization information system of the platform in the future

DNA-directed self-assembly of three-dimensional plasmonic nanostructures for detection by surface-enhanced Raman scattering (SERS)

AbstractSurface-enhanced Raman scattering (SERS) is a promising technology owing to its single-molecular sensitivity and molecular specificity. However, producing strong and stable SERS signal from plasmonic nanostructures remains a challenge. Herein, we present a facile generation of SERS-active nanomaterials by organizing metallic nanoparticles onto dye-labeled three-dimensional DNA nanostructures. Stable formations of metal clusters with the dye located in hot spots enabled detection of SERS signals. SERS signals were further regulated via interaction of pyramidal DNA scaffold with target biomolecules. We believe our SERS-active nanomaterials with controllable geometry and reversible SERS effects meet significant requirements for practical SERS-based sensors. By integrating versatile properties of DNA and introducing various Raman dyes into plasmonic nanostructures, the emergence of powerful and multiplexed biosensors should be possible

Improved interface control for high-performance graphene-based organic solar cells

The demand for high-efficiency flexible optoelectronic devices is ever-increasing because next-generation electronic devices that comprise portable or wearable electronic systems are set to play an important role. Graphene has received extensive attention as it is considered to be a promising candidate material for transparent flexible electrode platforms owing to its outstanding electrical, optical, and physical properties. Despite these properties, the inert and hydrophobic nature of graphene surfaces renders it difficult to use in optoelectronic devices. In particular, commonly used charge transporting layer (CTL) materials for organic solar cells (OSCs) cannot uniformly coat a graphene surface, which leads to such devices failing. Herein, this paper proposes an approach that will enable CTL materials to completely cover a graphene electrode; this is done with the assistance of commonly accessible polar solvents. These are successfully applied to various configurations of OSCs, with power conversion efficiencies of 8.17% for graphene electrode-based c-OSCs (OSCs with conventional structures), 8.38% for i-OSCs (OSCs with inverted structures), and 7.53% for flexible solar cells. The proposed approach is expected to bring about significant advances for efficiency enhancements in graphene-based optoelectronic devices, and it is expected that it will open up new possibilities for flexible optoelectronic systems

Improved Interface Control for High-Performance Graphene-Based Solar Cells

The demand for high-efficiency flexible optoelectronic devices is ever-increasing because next-generation electronic devices that comprise portable or wearable electronic systems are set to play an important role. Graphene has received extensive attention as it is considered to be a promising candidate material for transparent flexible electrode platforms owing to its outstanding electrical, optical, and physical properties. Despite these properties, the inert and hydrophobic nature of graphene surfaces renders it difficult to use in optoelectronic devices. In particular, commonly used charge transporting layer (CTL) materials for organic solar cells (OSCs) cannot uniformly coat a graphene surface, which leads to the inevitable devices failing. Herein, this paper proposes an approach that will enable CTL materials to completely cover a graphene electrode; this is done with the assistance of commonly accessible polar solvents

Freshwater Biodiversity Platform (FBP): an Integrated Information Management System of Freshwater Ecosystem for the Conservation and Sustainable Use of Biodiversity

Since the Nagoya Protocol on Access to genetic resources and Benefit Sharing (ABS) came into force in 2014, the conservation and assurance of national biodiversity has been internationally stressed. The Government of South Korea is exercising significant efforts to integrate and manage the information pertaining to biological resources in line with this global trend. However, connecting and sharing biodiversity data has certain challenges because the existing databases and information systems are being operated using different standards. In the present study, we established an integrated management system for freshwater biodiversity information, the Freshwater Biodiversity Platform (FBP), to support the conservation and sustainable use of biodiversity. This platform allows the management of various types of biodiversity data, such as occurrences, habitats and genetics, for freshwater species inhabiting South Korea. The data fields are based on a global biodiversity data standard, Darwin Core, and national biodiversity standards of South Korea in order to share our data more efficiently, both nationally and internationally. It is important to note that the platform deals with information related to the utilization of biological resources as well as information representing the national biodiversity. We have collected bibliographical data, such as papers and patents, from databases, including information on the use of biological resources. The data have been refined by applying a national species list of South Korea and ontology terms in (MeSH) to compile valuable information for biological industries. Furthermore, our platform is open source and is compatible with multiple language packs to facilitate the availability of biodiversity data for other countries and institutions. Currently, the Freshwater Biodiversity Platform is being used to collect and standardize various types of existing freshwater biodiversity data to build foundations for data management. Based on these data, we will improve the platform by adding new systems that can analyze and release data for public access. This platform will provide integrated information on freshwater species from the Korean Peninsula to the world and contribute to the conservation and sustainable use of biological resources