Abstract: In recent years, reducing carbon emissions has become a shared global challenge, requiring international cooperation and coordination. Multinational enterprises can lower carbon emissions during production by adopting low-carbon technologies; however, determining the optimal timing for adopting such technologies has become a key concern for firms. This paper builds a transnational manufacturing network influenced by carbon tax policies, consisting of an original equipment manufacturer (OEM) and two contract manufacturers (CMs). By employing optimal stopping theory and game theory, it analyzes the critical and optimal production quantities for adopting low-carbon technologies under collaborative and Stackelberg decision-making scenarios, and explores the optimal timing for adoption. To mitigate the cost pressures from carbon taxes and rapidly increasing exchange rates, it proposes a cost-sharing contract. This contract effectively reduces international trade risk and helps the supply chain achieve optimal performance. The findings reveal that under collaborative decision-making, the critical production threshold for optimal stopping is affected by both carbon tax rates and market volatility. Raising the carbon tax rate lowers the threshold for investing in low-carbon technologies and accelerates their adoption; similarly, market stability also encourages adoption. Under Stackelberg decision-making, the optimal production quantity of firms is jointly influenced by exchange rates, carbon taxes, carbon emission volumes, and the carbon reduction efficiency of the low-carbon technology. As carbon taxes, exchange rates, and emission reduction efficiency increase, firms become more inclined to adopt low-carbon technologies. Overall, the government plays a vital role in promoting corporate adoption of low-carbon technologies and in advancing carbon emission reduction efforts.

Key words: carbon tax, low-carbon technologies, timing of adoption, optimal stopping waiting, Stackelberg game

摘要： 近年来，减少碳排放是全球共同面临的挑战之一，亟须广泛的国际合作与协调。跨国企业可通过采纳低碳技术降低生产碳排放，而采纳低碳技术的最优时机问题又成为企业关注的焦点。基于碳税政策下的离岸外包跨国生产网络，构建了一个由原始设备制造商（OEM）和两个合同制造商（CM）组成的跨国制造链模型，运用最优停止等待和博弈理论，分析了协同决策与Stackelberg决策下企业采纳低碳技术的临界产量与最优产量，探讨了低碳技术的最优采纳时机。为减轻碳税和汇率上涨过快的压力，设计了成本分担契约，该契约能有效降低国际贸易风险成本，推动供应链实现最优状态。研究发现：协同决策情形下，企业最优停止的临界产量受碳税和市场波动率影响。政府提高碳税税率能降低企业投资低碳技术的临界产量，从而加快低碳技术的采纳；市场稳定有助于促进企业采用低碳技术。在Stackelberg决策中，企业最优产量受汇率、碳税、碳排放量及低碳技术碳减排率共同影响，碳税、汇率和碳减排率的提高均促使企业更倾向于采纳低碳技术。研究表明，政府在推动企业通过低碳技术降低碳排放的过程中发挥着更为重要的作用。

关键词: 碳税, 低碳技术, 采纳时机, 最优停止等待, Stackelberg博弈