Green technology innovation with environmental constraints
采用实物期权方法研究环境规制对企业绿色技术创新投资时机的影响，发现两者呈U型关系，并存在最优环境约束水平，政府可据此鼓励企业尽早投资。
In this paper, we employ the real-option approach to investigate the impact of environmental constraints (regulations) on a firm's green technology innovation investment decisions. We discover that the relationship between the timing of green technology innovation and the intensity of environmental constraints follows a U-shaped pattern, which provides a potential explanation for the conflicting predictions on the relationship between green technology innovation and environmental constraints in the empirical findings. Critically, our findings suggest that there is an optimal level of environmental constraints, which can be chosen by the government to encourage firms to undertake green technology innovation investments sooner. Furthermore, we find that the optimal environmental constraints first loosen and then tighten as business risk increases.