A bibliographic analysis of recent solar energy literatures: The expansion and evolution of a research field

This paper characterizes the solar energy literature from 1992 to 2011 using bibliometric techniques based on databases of the Science Citation Index and the Social Science Citation Index. Journal articles were the most frequently used document type representing 86.4% (6670) of the records. The pace of publishing in this field increased exponentially over these two decades, with the US accounting for the highest h-index (87) and the most publications (1273), followed by China and India. The US also plays a central role in the collaboration network among the 20 most productive countries, while China and India do not because of their more limited cross-national authorships. The Indian Institute of Technology was the organization with the most records (126), but it has few multinational co-authored articles. In contrast, the Paul Scherrer Institute in Switzerland is central to the collaboration network. The largest number of retrieved journal articles was in the area of energy applications (1059 articles) followed by light absorbing materials (983) and solar cells (420). Energy applications mainly address hydrogen, desalination, air conditioning, drying, heat pumps, biomass, and water splitting, while the light absorbing material mainly cover nano materials, TiO2, semiconductors, thin films, phase change material and so on. This analysis not only identifies global hotspots in solar energy research, but may also influence researchers' selection of future studies and publications.