How does industrial agglomeration affect green innovation efficiency in high-tech industries?—Evidence from China

Innovation is the primary driving force for national development, and industrial agglomeration is one of the key ways to improve the green innovation efficiency (GIE). Taking the data of 30 provinces in China from 2011 to 2021, we use the undesired SBM model to calculate the GIE, and utilize the interaction term method and threshold model to analyze the mechanisms of different agglomeration modes on it. The results show that the GIE of China's high-tech industries has steadily improved over time, and the efficiency of eastern region is higher than central and western regions. In high-tech industries, the existence of Williamson hypothesis is verified. The impacts of specialized and diversified agglomerations on GIE have double threshold effects of economic development. Following economic growth, the marginal effects of specialized agglomeration on GIE gradually decrease until turn to negative effects, while the effects of diversified agglomeration are always positive. The impacts of industrial agglomeration on GIE vary with different regions. The negative impacts of specialized and diversified agglomerations in eastern region have emerged. Consequently, China should encourage reasonable high-tech industrial agglomeration and prevent the negative impacts of excessive agglomeration at the same time, trying to mitigate the specialized agglomeration, actively give play to the advantages of diversified agglomeration and promote industries diversified integration and technology spillovers.