The key role plays a pivotal fulcrum in fostering interdisciplinary innovation. This study examines the structure and function of key roles in disciplinary convergence. We conducted a comprehensive analysis using the Web of Science SCIE database, gathering 4,904 scientific papers published between 2016 and 2022. These publications were authored by 94 scholars who received funding from China's major research initiative "High-performance Materials based on Functional Units and their Ordered Structures." Utilizing a brokerage analysis method, we constructed a scholar-following network to delineate knowledge flows and identify key roles. Subsequently, we analyzed the evolution patterns and distribution features of these key roles. Through scientometric and Pearson correlation analysis, we uncovered the diverse functions of key roles in disciplinary convergence innovation. Our findings reveal that key roles in the materials field include coordinator, representative, and gatekeeper. Over time, there has been an increasing concentration of scholars assuming all three key roles, as well as those serving as both representative and gatekeeper (referred to as external key roles). Notably, the concentrations of representative and gatekeeper surpass that of coordinator across disciplines, excluding the materials field. Furthermore, we observed positive correlations between the concentrations of all three key roles and disciplinary convergence level, with external key role concentration demonstrating stronger correlations. Overall, our research provides valuable theoretical insights and practical implications for advancing disciplinary convergence through the lens of key roles.