Geographic and Technological Perspectives on "Photovoltaic Cells: " Patents as Instruments for Exploring Innovation Dynamics

The dynamics of innovation are nonlinear and complex: geographical, technological, and economic selection environments can be expected to interact. Can patents provide an analytical lens to this process in terms of different attributes such as inventor addresses, classification codes, backward and forward citations, etc.? Two recently developed patent maps with interactive overlay techniques—Google Maps and maps based on citation relations among International Patent Classifications (IPC)—are elaborated into dynamic versions that allow for online animations and comparisons by using split screens. Various forms of animation are explored. The recently developed Cooperative Patent Classifications (CPC) of the U.S. Patent and Trade Office (USPTO) and the European Patent Office (EPO) provide new options for a precise delineation of samples in both USPTO data and the worldwide patent database PatStat of EPO. Among the “technologies for the mitigation of climate change” (class Y02), we zoom in on nine material technologies for photovoltaic cells; and focus on one of them (CuInSe2) as a lead case. The longitudinal development of Rao-Stirling diversity in the IPC-based maps provides a heuristics for studying technological generations during the period under study (1975-2012). The sequencing of generations prevails in USPTO data more than in PatStat data because PatStat aggregates patent information from countries in different stages of technological development, whereas one can expect USPTO patents to be competitive at the technological edge.