Technological industry agglomeration, green innovation efficiency, and development quality of city cluster

Technological progress, especially green innovation, is a key factor in achieving sustainable development and promoting economic growth. In this study, based on innovation value chain theory, we employ the location entropy, super-efficiency SBM-DEA model, and the improved entropy TOPSIS method to measure the technological industry agglomeration, two-stage green innovation efficiency, and development quality index in Yangtze River Delta city cluster, respectively. We then build a spatial panel simultaneous cubic equation model, focusing on the interaction effects among the three factors. The findings indicate: (1) There are significant spatial links between the technological industry agglomeration, green innovation efficiency, and development quality in city cluster. (2) The development quality and technological industry agglomeration are mutually beneficial. In the R&D stage, green innovation efficiency, development quality, and technological industry agglomeration compete with each other, while there is a mutual promotion in the transformation stage. (3) The spatial interaction among the three factors reveals the heterogeneity of two innovation stages. The positive geographical spillover effects of technological industry agglomeration, green innovation efficiency, and development quality are all related to each other. This paper can provide a reference for the direction and path of improving the development quality of city clusters worldwide.