Specifying international research network diagram in growing field

An innovation model providing a solution for climate change and sustainable economic growth is required. In this scenario, clean energy is the most promising technology. Their research requires a considerable amount of R&D expenditure and various core technologies. Therefore, international research collaboration is effective for prompt and efficient development. With countries and organizations contributing to the rapid growth of knowledge, the meta-structure of international research and collaboration has become ambiguous. Our paper aims to establish a knowledgebase that can help to prepare international research collaboration policies for solving global challenges effectively. We demonstrate research capacity and international research collaboration in solar cell, fuel cell technologies and service science, using global research network diagrams gathered from 35, 322, 33, 136 and 50,035 academic papers respectively. The diagram includes the data of research competency of countries or institutions and of co-authorship. More than 6,000 institutions and 100 countries are involved in each field. Based on the diagrams, the clean energy technologies and service science are compared and international collaboration is analyzed. A valley of research collaboration in Asia and a gap between the collaboration structures of the both technologies are identified. Then, science and education policies which influence the structures are discussed.