A study of technological collaboration in solar cell industry using patent analysis

This study examines the technological collaboration in solar cell industry by using the information of patent assignees and inventors as defined by the United States Patent and Trademark Office (USPTO). Three different collaborative types, namely local (same city), domestic (different cities of the same country), and international collaboration are discussed. The general status of solar cell patent collaborations, transforming trends of collaborative patterns, average numbers of assignees and inventors for three collaborative types, and international collaboration countries are studied. It is found that co-invented patents and co-assigned patents have both increased in numbers during the four decades; the collaboration of technology owners is very low, while the collaboration of inventors is active. Domestic collaboration is the main collaborative pattern for both assignee collaboration and inventor collaboration. The other two collaborative types show contrary trends: international collaboration has slowly risen in the past decades while local collaboration dwindled away. The US has the largest number of internationally collaborative patents in worldwide, though such patents occupy a low portion of total US patents. In contrast, China has small number in total patents and internationally collaborative patents, but its international collaborative shares are higher.