At present, the continuous stream of educational reforms worldwide mandates innovation and flexibility within school organizations to augment their adaptability to environmental shifts and pedagogical transformations. Traditional, fixed job responsibilities are rendered inadequate in the face of such dynamic changes ^[1][2][1,2], hence elevating the significance of teachers’ organizational citizenship behavior. This behavior, metaphorically seen as a “lubricant”, bolsters school organizational efficacy [3].

For example, as the curriculum reform deepens and the emergence of interdisciplinary courses pairs with the growth of research-oriented learning, the roles and responsibilities of teachers should transcend the confines of conventional subject teaching [4]. An essential requisite in this evolving educational scenario is the development of teachers’ awareness and abilities in interdisciplinary teaching, an achievement possible only through extensive collaboration and altruistic assistance among faculty across diverse disciplines [5]. Herein, the organizational citizenship behavior plays a cardinal role, as it encourages teachers to aid others selflessly. This behavior is inclusive of the critical practice of knowledge-sharing in interdisciplinary courses, thereby fostering an environment of collective growth and shared wisdom [6].

Nevertheless, the subtle and non-economic nature of teachers’ work renders many behaviors and performance outcomes challenging to delineate or quantify for assessment and motivation purposes [7]. Hence, if school organizations aspire for teachers to undertake informal tasks that lack comprehensive regulation yet maintain the organization’s competitive edge [8], then the engagement in organizational citizenship behavior becomes of paramount importance for teachers. This non-structured, extra-role behavior can indeed help in advancing the educational mission and promoting an overall beneficial academic environment.

The advent of organizational citizenship behavior can be attributed to many factors, with transformational leadership serving as a notable determinant [9]. Transformational leaders adeptly articulate the organization’s vision to its employees, bolstering employee identification through the presentation of attainable prospects [10]. These leaders inspire employees to exhibit high levels of commitment and altruism, thus encouraging them to prioritize collective interests over individual ones [11]. Moreover, transformational leadership cultivates a congenial organizational atmosphere, facilitating employees in recognizing their self-worth within an engaging working environment and propelling the achievement of organizational objectives [12].

In a recent meta-analytical study, de Geus et al. demonstrated that positive leadership (encompassing both transformational and ethical leadership) exerts a significantly positive influence on subordinates’ organizational citizenship behavior within the public sectors [13]. Despite the abundance of research corroborating the significance of positive transformational leadership behavior for fostering subordinates’ individual-level organizational citizenship behavior ^{[14][15][16][17]}[14,15,16,17], the inherent mechanism underpinning how transformational leadership successfully activates subordinates’ organizational citizenship behavior warrants further exploration. Such research will serve to clarify the nuanced interactions between leadership behaviors and their impacts on organizational citizenship actions.

In the realm of transformational leadership, scholars have identified its influence at two distinct levels: the individual and the group level [18]. Group-focused transformational leadership directs its attention towards collective entities, emphasizing shared objectives and interests, fostering group identification, and inspiring effective collaboration towards common goals [10]. Conversely, individual-focused transformational leadership shifts its focus towards individual constituents, tailoring guidance and assistance based on deep understanding, resulting in varied perceptions among group members [10]. While theory suggests that transformational leadership operates at both levels ^[19][20][21][19,20,21], current scholarly work often treats it as a single construct tied primarily to job performance outcomes ^[22][23][24][22,23,24]. Scholars advocate for more a nuanced exploration of the impact mechanisms at each level, especially regarding the motivational mechanisms of group-focused and individual-focused transformational leadership ^{[10][19][21][25][26]}[10,19,21,25,26].

2. Theoretical Framework

Self-determination theory offers a robust framework for comprehending the motivation and quality of human behavior ^[27][49]. The core tenet of this theory asserts that the influence of various environmental factors (including job design, contingency pay, leadership style) on subordinates’ motivation and experience is largely mediated by a set of basic psychological needs (competence, autonomy, and relatedness) ^[28][50]. Burns first introduced the concept of transformational leadership, shifting the focus of leadership research towards how leaders can change and transform the values, interpersonal relationships, organizational culture, and behavior patterns within an organization ^[29][51]. He viewed leadership as an evolving process of mutual influence between leaders and followers, where leaders and followers work together to stimulate intellect and inspire spirits to drive organizational transformation ^[29][51]. Transformational leadership involves leaders making their subordinates aware of the meaning of the tasks they undertake, inspiring high-level needs in their subordinates, and establishing a mutual trust atmosphere ^[30][52]. In certain situations, subordinates may even sacrifice personal interests for the benefit of the organization and achieve results that exceed their initial expectations ^[17][31][32][17,41,53]. This leadership style triggers intrinsic motivation in subordinates, making them more committed to their work, and hence driving organizational change and progress ^[33][34]. Kovjanic et al. contend that, viewed through the lens of self-determination theory, transformational leadership can be interpreted as bolstering the quality and quantity of followers’ job performance by supporting their fundamental psychological needs ^[33][34]. When these basic psychological needs are sustained by external environmental stimuli, followers perceive these as symbolic and expressive facets of their self-concept and adopt shared values and goals as their guiding principles ^[28][50]. There exists a discernible relationship between transformational leadership, characterized as a needs-supportive leadership style, and subordinates’ basic psychological needs and autonomous motivation ^[34][54]. This relationship could constitute one of the mechanisms through which transformational leadership impacts the quality and quantity of subordinates’ work ^[35][33]. In a recent study, Amor et al. investigated the relationship between transformational leadership behavior and subordinates’ work engagement based on the self-determination theory and psychological contract theory ^[36][55]. They also examined the partial mediating role of structural empowerment in this relationship. Their findings suggested that high-level transformational leadership could enhance subordinates’ sense of structural empowerment by providing them with access to information, opportunities, support, and ample resources, thereby promoting work engagement. This study, drawing from the theoretical framework of Amor et al., substitutes the psychological contract for structural empowerment as a mediating variable. This is based on the premise that the fulfillment of a psychological contract and psychological empowerment are interdependent and, as acknowledged by the authors, psychological empowerment is a precursor to structural empowerment ^[36][55]. However, the application of the psychological contract as a mediating variable in the research of transformational leadership is relatively rare. Chen et al. considered the psychological contract as a mediating variable in exploring the relationship between transformational leadership and subordinate emotional labor ^[37][28]. Therefore, by referencing Chen et al., this study incorporates the psychological contract as a mediating variable into the research framework to further elucidate the mechanisms of transformational leadership. While Chen et al.’s design considering the psychological contract as a mediating variable offers theoretical support for this study, their research only accounted for relational and transactional psychological contracts, neglecting developmental psychological contracts, which are equally significant in this study. Developmental psychological contracts emphasize the mutual responsibilities of the employer and employee regarding future career success and development ^[38][56]. This includes job roles with developmental space, challenging job content, obtaining a sense of achievement and satisfaction in the job, and voluntarily taking on extra-role work tasks, such as the exchange and sharing of work skills ^[39][57]. These concepts align closely with the philosophy of group-focused transformational leadership, which strives to paint an appealing future vision, encourages subordinates’ participation in decision-making, collaboratively establishes group goals, and sets high performance expectations based on these goals ^[40][58]. A compelling vision can cause teachers to perceive their job roles as having developmental space ^[41][59]. Group goals prompt group members to voluntarily take on extra-role work tasks ^[42][60]. Setting high-performance expectations based on group goals makes teachers’ job content more challenging ^[43][61]. This challenge may stimulate teachers’ intrinsic motivation, encouraging them to utilize their abilities fully while accomplishing group goals ^[43][61]. Under the stimulation of intrinsic motivation, the degree of accomplishment of group goals may exceed initial expectations. This unexpected exceedance could provide teachers with a greater sense of achievement and satisfaction in their work ^[44][62]. Still, the study by Amor et al. treats transformational leadership as a single holistic construct, refraining from a segregated analysis of the respective impact mechanisms of group-focused and individual-focused leadership on essential psychological elements and job performance ^[36][55]. The majority of the prevailing literature attributes the fulfillment of psychological contracts at an individual level to individual-focused transformational leadership ^[45][46][29,63], particularly the notion that transformational leadership augments psychological contract satisfaction via certain individualized consideration behaviors ^[46][63]. These studies, to a certain degree, overlook the significant role that group-focused transformational leadership plays in bolstering internal group objectives ^[40][58] and fostering group cohesion ^[47][64]. Consequently, it is of importance to address this gap and illuminate the contribution of group-focused transformational leadership to the fulfillment of psychological contracts. Lastly, Rousseau and Fried argue that cultural conditions exert a profound impact on theoretical constructs, necessitating a distinct approach when analyzing disparate countries ^[48][65]. With the rapid progression of reform and liberalization in the past few decades, China has undergone a pivotal transition from a planned economy to a market-oriented one, resulting in significant shifts in societal values ^[49][66]. Nevertheless, the imprint of a collectivist culture remains profound within the Chinese populace, influencing elements such as personality development, attitude formation, and behavioral norms to a considerable extent ^[50][67]. Hofstede extensively explored collectivism on the national cultural level, deeming it a vital dimension for cultural categorization and identifying China as a paradigmatic collectivist nation ^[51][68]. As research advanced, scholars shifted their focus towards the comprehension of collectivist culture at the individual and group levels. Among these, group collectivist orientation emerged as a group-level variable, representing an underlying set of norms and cultural ambiance within a group ^[52][69]. It accentuates the importance of harmonious relations within groups, encourages employees to internalize the group’s goals, promotes concern for the welfare of the group and colleagues, and underscores the subordination of individual goals to group objectives ^[53][70]. According to the concept of leader–follower value congruence ^[54][71], when subordinates’ values align with the leadership style in terms of ideology, subordinates are more likely to respond strongly to that leadership style, whereas the influence of this leadership style on subordinates is comparatively weaker when there is a divergence in values. Group-focused transformational leadership places importance on collective awareness and group objectives ^[55][72], encouraging group members to collaborate synergistically for the attainment of common goals ^[56][73]. Group members with a high degree of group collectivism tend to adhere to collective norms, prioritize group objectives, and actively participate in cooperative endeavors ^[57][74]. This alignment corresponds with the ideology of group-focused transformational leadership. Consequently, group members immersed in a high-level group collectivist atmosphere are more likely to internalize the leadership’s group values, leading to a manifestation of organizational citizenship behavior ^[58][75]. Conversely, group members in a low-level group collectivist atmosphere hold self-centered values ^[59][42], which can be viewed as incongruent with the ideology of group-focused transformational leadership. As a result, for such employees, the impact of group-focused transformational leadership on organizational citizenship behavior might be relatively weaker. In the realm of education, teachers, shaped by various cultural value orientations, adhere to divergent behavioral norms. This divergence can precipitate substantial differences in the influence of certain factors on teachers’ organizational citizenship behavior ^[60][76]. To address this phenomenon and to respond to Bass’s proposition that transformational leadership initially conceptualized and measured within the individualistic context of the United States appears equally, if not more, applicable in the collectivist societies of Asia ^[61][44], this study incorporates collectivist culture as a moderating variable. This is achieved within the research framework to expand upon the model proposed by Amor et al. ^[36][55]. The incorporation is intended to shed further light on the boundary conditions pertinent to the impact of group-focused transformational leadership on teachers’ organizational citizenship behavior, thereby enhancing the comprehension of such behavior within Chinese educational institutions. This approach is significant, as, in a collectivist group, an emphasis is often placed on group cooperation and common interests. In such a context, subordinates may demonstrate a greater inclination to respect their leaders ^[62][63][40,77], aligning with the group values promoted by leadership ^[54][71], thus potentially amplifying the impact of transformational leadership.