**2. Literature Review**

#### *2.1. Cooperation in Green Supply Chain*

Green supply chain cooperation has an important impact on sustainable product development and operations mode [11–15] and has become a positive change in corporate strategy for various companies [14,15]. Cooperation can be divided into vertical and horizontal cooperation and among the two types of cooperation and their cooperation performance is impacted by different ways [16–22]. The literature shows that vertical cooperation in the supply chain can improve supply chain decision-making and performance through information sharing, thereby achieving a win–win situation [16–18]. In the horizontal cooperation, two competitive retailers can cooperate to purchase and obtain a quantity discount, thereby influencing their profits [19].

In addition, for the purpose of realizing the green and economic performance of products, supply chain members mainly adopt two typical ways in the green cooperation of a supply chain: alliance and cost sharing contracts [23]. For example, Ge et al. showed that both cooperation and competition will tend toward a green technology alliance, and the company's decision to cooperate will change with the change in the endogenous knowledge sharing rate [24–26].The second model is to stimulate the green investment of members through supply chain contracts and deal with the coordination of green channels. For example, Yenipazarli et al. analyzed the effects of retailer supplier cooperation on profit/cost and the environmental effects on the supply chain under two upstream and downstream contracts [27]. When members of the supply chain share the cost, on one hand, it can make products greener. On the other hand, it can make the overall profit of the supply chain increase [21,28–30]. Therefore, it is necessary to discuss how to cooperate with supply chain partners to improve corporate performance.

#### *2.2. Value Co-Creation Behavior in the Supply Chain*

Michael (1980) suggests that the value creation of an enterprise is composed of internal production and operations routines that create value. However, with the continuous change in the market competition environment, the creation process of enterprise value cannot be limited to the inside of the enterprise [31], but is co-created by the cooperative network composed of enterprises [32]. Enterprises can improve the efficiency, quality, cost, and other aspects of the whole supply chain through cooperative implementation of strategic management [33].

Prahalad et al. proposed value co-creation as a new method of value creation [34] and believe that value originates not only from producers, but from the joint creation of consumers and enterprises or other relevant stakeholders. Ultimately, the value is determined by the consumer. From the perspective of stakeholders, the meaning of a "company" is a relationship that exists between individuals or groups that affect the company's business or is affected by it, and the purpose for which a business is established forms the basis for whether a stakeholder establishes relationships and cooperates with them [35]. In this relationship, stakeholders are the unity of recipients of value and the value creators/co-creators [36]. Multiple stakeholders have an impact on the business environment and company efficiency by providing resources and benefit from it [37]. Therefore, the joint efforts of stakeholders are the most important part of value co-creation [38]. In addition, stakeholders must first have a common purpose to collaborate [39] and then also encourage the positive contributions of members [40].

Value creation usually occurs in the process of using products or services [41]. The fierce market competition requires the enterprises in the supply chain to strengthen cooperation and establish a value network. Many scholars have studied the vertical cooperation among enterprises, that is, the cooperation between enterprises and suppliers and retailers. Enterprises can create more value for the supply chain through information sharing, resource integration, and process integration with upstream and downstream partners [29,42–47]. Some scholars have also paid attention to the horizontal cooperation between supply chain enterprises and competitors, but there have been few studies. D'Aspremon et al. and Kamien et al. introduced the concept of horizontal Research & Development. cooperation in theory early on [48,49]; Ge et al. and Dai et al. compared different horizontal cooperation modes of green supply chain [22,23]; and Luo et al. studied the green technology investment of two manufacturers in a competitive and cooperative environment [50]. Gnyawali et al. applied practical case analysis, and concluded that competitive cooperation is beneficial to the development of advanced technology [51]. Therefore, our research focused on three different types of value co-creation: co-creation with suppliers, co-creation with retailers, and co-creation with competitors.

#### *2.3. Value Co-Creation and Performance*

Research shows that value co-creation behavior benefits both suppliers and customers [52]. For customers, value co-creation mainly focuses on the customer dimension, which is a relatively new research field [53]. Most of the relevant studies have focused on the development of measurement tools to study customer co-creation value across different research backgrounds [54–56]. Co-creation practices enable interaction and communication between customers and enterprises, so as to benefit customers who participate. Active participation in co-creating value makes them more satisfied than those who are not [57], encourages customers to be more innovative [58], and increases the customers' enthusiasm and willingness to take risks [59]. At the same time, the perceived value gained from value co creation will increase customer commitment [60], and psychological attachment, which increases the willingness of customers to make more voluntary efforts in the cooperative relationship. The increase of customer value in value co-creation improves the customer experience in supplier relationships [61], and establishes customer loyalty [62].

For enterprises, value co-creation is realized through the establishment of a co-operation relationship between two or more parties in the supply chain, so as to jointly obtain strategic benefits and improve the operation efficiency, economic performance, and service performance of enterprises [63–65], which is also the key success factor of enterprises in delivering products and services [66]. Through value co-creation, companies have a positive impact on service performance and environmental performance [67,68]. Through the green internal innovation process and green technology investment research and development, it can promote enterprises to develop green energy-saving products and realize energy-saving and emissions reduction of the whole supply chain [69,70]. The optimal strategy of the enterprise and the performance of the supply chain will change due to different cooperation models [17,18,21,71]. Thus, this study will examine different performances (i.e., operational performance, innovation performance and financial performance) of value co-creation in the supply chain and the changes in performance under different contextual factors.
