title: Bulk-Heterojunction Organic Solar Cells: Five Core Technologies for Their Commercialization.
abstract: The past two decades of vigorous interdisciplinary approaches has seen tremendous breakthroughs in both scientific and technological developments of bulk-heterojunction organic solar cells (OSCs) based on nanocomposites of π-conjugated organic semiconductors. Because of their unique functionalities, the OSC field is expected to enable innovative photovoltaic applications that can be difficult to achieve using traditional inorganic solar cells: OSCs are printable, portable, wearable, disposable, biocompatible, and attachable to curved surfaces. The ultimate objective of this field is to develop cost-effective, stable, and high-performance photovoltaic modules fabricated on large-area flexible plastic substrates via high-volume/throughput roll-to-roll printing processing and thus achieve the practical implementation of OSCs. Recently, intensive research efforts into the development of organic materials, processing techniques, interface engineering, and device architectures have led to a remarkable improvement in power conversion efficiencies, exceeding 11%, which has finally brought OSCs close to commercialization. Current research interests are expanding from academic to industrial viewpoints to improve device stability and compatibility with large-scale printing processes, which must be addressed to realize viable applications. Here, both academic and industrial issues are reviewed by highlighting historically monumental research results and recent state-of-the-art progress in OSCs. Moreover, perspectives on five core technologies that affect the realization of the practical use of OSCs are presented, including device efficiency, device stability, flexible and transparent electrodes, module designs, and printing techniques.
authors.affiliation: School of Materials Science and Engineering, Research Institute for Solar and Sustainable Energies, GIST-ICL International Collaboration R&D Centre, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.
authors.forename: Hongkyu
authors.initials: H
authors.lastname: Kang
authors.affiliation: School of Materials Science and Engineering, Research Institute for Solar and Sustainable Energies, GIST-ICL International Collaboration R&D Centre, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.
authors.forename: Geunjin
authors.initials: G
authors.lastname: Kim
authors.affiliation: School of Materials Science and Engineering, Research Institute for Solar and Sustainable Energies, GIST-ICL International Collaboration R&D Centre, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.
authors.forename: Junghwan
authors.initials: J
authors.lastname: Kim
authors.affiliation: School of Materials Science and Engineering, Research Institute for Solar and Sustainable Energies, GIST-ICL International Collaboration R&D Centre, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.
authors.forename: Sooncheol
authors.initials: S
authors.lastname: Kwon
authors.affiliation: School of Materials Science and Engineering, Research Institute for Solar and Sustainable Energies, GIST-ICL International Collaboration R&D Centre, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea. heejook@gist.ac.kr.
authors.forename: Heejoo
authors.initials: H
authors.lastname: Kim
authors.affiliation: School of Materials Science and Engineering, Research Institute for Solar and Sustainable Energies, GIST-ICL International Collaboration R&D Centre, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea. klee@gist.ac.kr.
authors.forename: Kwanghee
authors.initials: K
authors.lastname: Lee
keywords: bulk heterojunctions; conjugated polymers; organic solar cells; polymer solar cells; printing technology