Abstract: As consumers increasingly prefer green energy-efficient products, enterprises engage in green research and development (R&D) to improve the environmental performance of their products and strengthen  market competitiveness. However, because green R&D exhibits spillover effects, competitors can easily learn from or imitate these efforts, reducing their won R&D costs. Some competitors may even “leapfrog” and achieve an advantage in product greenness. This creates a dilemma for firms: should they engage in green R&D early to gain a first-mover advantage, or should they wait and benefit from competitors’ spillovers? To address problem, this paper develops a two-period duopoly game model. The results show that the there are two pure-strategy Nash equilibria in the timing of green R&D. When the spillover rate is low, the duopolies choose to conduct green R&D in the first period. However, the equilibrium profit in this scenario is lower than if they conduct R&D in the second period, creating a classic prisoner’s dilemma. When the spillover rate is high, the duopolies choose to conduct green R&D at different periods. In this case, the firm that invests first achieves higher profits and exerts greater R&D effort than the later firm. As the spillover rate increases, the first-mover’s profit and R&D effort gradually decline, while the second-mover’s profit and effort increase. Furthermore, in the scenario where the two firms conduct R&D in different periods, a mixed-strategy Nash equilibrium also exists. In this case, the probability that each firm conducts green R&D in the second period increases with the spillover rate.

Key words: spillover effects, duopoly competition, green research and development (R&D)

摘要： 在消费者日益偏好绿色节能产品的背景下，为提升市场竞争力,企业倾向于开展绿色研发以提升产品绿色水平。然而，由于绿色研发具有外溢性，其成果易被竞争对手学习和模仿，这将使得竞争对手的研发成本降低，甚至可能使竞争对手因此“后来居上”，在绿色产品水平上取得领先。因此，企业面临着两难选择：是率先进行绿色研发以抢占市场，还是等待竞争对手研发、坐享溢出。为研究这一问题，本文构建了一个两时期双寡头竞争博弈模型。研究结果表明，双寡头在绿色研发时机的选择上存在两种纯策略纳什均衡：① 当溢出率较低时，双寡头均选择在第1时期进行绿色研发，但此时的均衡利润低于两企业均在第2时期研发的情形，双寡头因此陷入“囚徒困境”；② 当溢出率较高时，双寡头会选择在不同时期进行绿色研发。此时，先研发企业的利润与绿色研发努力程度均高于后研发企业，且随着溢出率的提高，先研发企业的利润与绿色研发努力程度逐渐降低，而后研发企业的利润与绿色研发努力程度逐步增加。此外，在双寡头先后进行绿色研发的情形下，还存在一个混合策略纳什均衡，在此均衡中，双寡头在第2时期进行研发的概率随着溢出率的上升而增加。

关键词: 溢出效应, 双寡头竞争, 绿色研发