Sustainability in Social Enterprise Research: A Systematic Literature Review

Given the noteworthy contribution to the global socio-economic development, research on social enterprises (SE) has gained prominence over past two decades. Making a clear departure from for-profit counterparts, the core purpose of SEs is to deliver a social mission while at the same time staying financially viable and as a consequence, “sustainability” is strongly embedded in their core drive of existence. Rapidly sprouting body of literature on SE posits that “sustainability” is intensely coincided with “social enterprises.” Although “sustainability” has been a buzz word in the context of SE, lacking of systematization and categorization of knowledge hinders the advancement of SE specific research. Consequently, the primary objective of this paper is systematization and categorization of the extant knowledge on sustainability in SE research context. The study carried-out a systematic literature survey from reputed databases; Scopus, Social Science Citation Index and Science Direct. Removing the repetitions, 136 papers on sustainability was compiled for analysis. The analytical approach was two-fold: First, a citation analysis was performed in order to evaluate the prominent, emerging and popular sustainability-based research areas in the extant body of knowledge in the field. Second, a thematic analysis was performed to analyze and interpret explicit themes on which sustainability concept has been investigated. Paper discovered six themes that the sustainability concept has been researched through significant research popularity disparities can be witnessed among the discovered themes. Since this paper identifies several research gaps and inconsistencies, it noticeably sets path for future research on the concept of sustainability in SE.


Introduction
Making a clear departure from mainstream commercial enterprises, social enterprises apply business-like practices such as being innovative, pro-active and taking risks to solve wicked social issues those are unaddressed by government or private sector (Stecker, 2014;Weerawardena & Mort, 2006). Thus, these ventures are perceived as change agents who combat with social and natural issues (Partzsch & Ziegler, 2011) while staying financially sustainable (Mair & Martí, 2006). In that course, it is evident that social enterprises involve with balancing two incompatible extremesdelivering social mission to create a sustainable social impact and creating financially sustainable ventures. This is in fact where the two unharmonious interests are crossing paths (Picciotti, 2017). Scrutinizing the existent body of literature, it is vital that the conception of "sustainability" is strongly set in within social enterprises (Gupta et al., 2020;Hota et al., 2020).
After the publication of the Brundtland Report in 1987 and then followed by the Earth Summits in Rio de Janeiro in 1992 and Johannesburg in 2002, sustainability has become as an emerging concept in the globe to address the principal issues of environmental problems. The World Commission on Environment and Development (1987, p. 8) defined sustainability as "development that meets the needs of the present without compromising the ability of future generations to meet their needs" in Brundtland Commission report. However, some argue that this definition is entirely focused on the macroeconomic approach as organizations find it difficult to decide their roles within these borders. Although some researchers have investigated the microeconomic applications of sustainability using this definition in the fields of management, operations, and engineering. However, conceptualizations of organizational sustainability exclusively focused on environmental sustainability, with the recognition of social and economic responsibilities (Carter & Rogers, 2008). Therefore, the concept of sustainability was evaluated and measured within the space of economic or environmental sustainability alone, nevertheless it made up with three pillars, namely environmental, economic, and social (Quarshie et al., 2016).
Consequently, the sustainability aspect is immensely investigated in social enterprise research setting on varied frontages such as delivering sustainable social impact (Nguyen et al., 2015), incubating sustainable innovations (Zahra et al., 2014), having sustainable business models (George et al., 2016), together with value creation and value dissemination by SE (Sulphey & Alkahtani, 2017). Interestingly, ever-growing inquiries on social enterprises are a vibrant sign that this is an emergent field of research. Conversely, it is apparent that "sustainability" is more or less a taken-for-granted term in social enterprise research. Many researches have interchangeably used social enterprises and sustainable enterprises. Thus, it is worthwhile to scientifically study how the notion "sustainability" has been researched in social enterprise context. This posits that there is a considerable need for organization and systemization of the extant stock of knowledge on how sustainability has been researched from social enterprise context. This has a timely need since the systemization will set path for future development of the context specific knowledge which has not been taken place in this field of research. Aligned with this requisite, the principal objective of this paper has been to systemize and organize the contemporary knowledge on how the notion sustainability has been researched from social enterprise research context to spot the knowledge lacunas which is going to be immeasurably worthwhile for future research. We conducted a systemic literature review to achieve our aforementioned objective (Gupta et al., 2020;Hota et al., 2020) since the approach led us to observe diverse themes that the research on sustainability has been evolved and to reflect on the missing links .
The rest of this paper is organized as follows: First, our methodology is extensively discussed. Second, data analysis and discussion section is presented where we present our: (a) citation analysis which was performed to evaluate the conspicuous, emerging, and prevalent sustainability-based research areas and, (b) thematic analysis which was performed to discover core themes that the sustainability has been researched in social enterprise research agenda. Last, we present our conclusion.

Methodology
This study adopted a systematic approach to identify and review the relevant literature to form the main themes. A systematic search was conducted. Research articles were selected from the well reputed data bases such as Web of Science, Social Science Citation Index as well as Google Scholar databases. Various search strings were developed dependent on the purpose of this study, and the searches were not limited by time. The Boolean "or," "and" operators were utilized for searching through articles as these terms have reciprocally been used by the SE scholars (Gupta et al., 2020). The query directed to 146 papers and after eliminating the repetitions or duplications a final list of 127 papers was selected, which were furthermore assessed according to following steps. The first step, the articles included were additionally screened dependent on their title and keywords to filter inappropriate articles, second stage involved an indepth reading of the abstracts of the research papers by scholar concurrently to filter out inappropriate ones and the last stage involved the analyzing of the full paper of each of the articles by researcher to additionally filter out unnecessary research papers. At the end of these all stage, 136 research papers were remaining and used for the final analysis purpose of this study. The bibliometric summary of the chosen articles is presented in Table 1.
"This study then analyzed the patterns of these over time and contrasted them with identical searches on the terms "social entrepreneur OR social entrepreneurship," "dual objective of social enterprise," "social enterprise tensions," "sustainability and social enterprise," "sustainable leadership," "sustainable enterprise," "green enterprises, missiondriven organizations, social purpose organizations" and "hybrid organizations." The rationale of using these large number of terms is that the researchers have used a large variety of terms to define and interpret socially conscious enterprises. Further, reference lists of articles were cross-searched in order to include eventual non-identified reviews. Hence, the systematic methodology was two-fold: First, a citation analysis was conducted in order to evaluate the prominent, evolving and famous sustainability related research in the existing knowledge base. Second, a thematic analysis was performed to analyze and explain explicit themes on which sustainability idea has been explored in social venture research settings. Thematic analysis was also used to explore explicit patterns of sustainability research in social enterprise setting.

Findings and Discussion
Our analysis was twofold: (a) citation analysis to evaluate most influential researches and, (b) thematic analysis to identify the main areas that sustainability has been researched in social enterprise research context.

Citation Analysis
The purpose of this analysis was to identify the most influential papers in the respective study themes based on citation records. After evaluation the citation records for all the papers selected for the final analysis (136), 50 papers were identified as most influential and Table 2 classifies the identified papers into diverse 6 clusters based on their content similarities-the overarching objectives of the research papers.
In view of the citation analysis performed based on most cited papers, we discovered six clusters that sustainability research has been progressed. They are namely: (a) Motives, (b) Paradigm shift-from non-profits to social enterprises, (c) Managing and management challenges, (d) Venture creation, growth and challenges, (e) Creating impact-social value creation, and (f) Cross country experience. Taking of the first cluster, the whole purpose has been to discuss the motives behind initiating social ventures and to explore the characteristics of the particular ventures. The second cluster in general, investigates the paradigm shift of social enterprising. The main focus in this theme has been to discuss the significance of nurturing financially viable ventures by deviating from dependency charity models. Thus, a significant attention has been devoted to nurturing business models within social enterprises to generate the cash flows to stay sustainable. The third cluster is on managing social enterprises and management challenges. Here, the theme largely discusses the significance of managing the hybridity-The mission and financial sustainability perspectives. In addition to this main focus, the theme also discusses specific challenges that social ventures face due to being "hybrid ventures." Among these challenges, funding, financing, marketing, new product development, and operational challenges are chiefly have received the attention of researchers. Further, specific attention has been devoted to "mission drift" to investigate the consequences of focusing more on the financial sustainability at the cost of social mission aspect. The fourth theme elaborates the aspect of creating and growing social conscious ventures. This theme focuses on seed financing, opportunity identification and social investing. Further, specific attention has been devoted to elaborate the challenges and methodologies sand patterns of scaling up for these ventures. The fifth theme specifically focuses on creating social impact and social value creation. Here, the scholars build theoretical models and empirically validated on how social ventures have to operate by keeping their social value creation philosophy at the core. Further, a special attention has been received to evaluate the social impact and the debate on developing measurements on measuring the social impact of these ventures are emerging at this time. The sixth theme evaluates the cross-country experience and the differences of defining, operating and nurturing social ventures. Here, the main focus has been to discuss the definitional ambiguities, operational diversities and to show case different models of social ventures from around the world.
Interestingly, some research clusters are enormously prominent than the other clusters. For instant, higher number of citations for Cluster 3 and Cluster 4 and Cluster 5 state that sustainability is intensively researched when investigating; (a) management and managerial challenges, (b) venture creation growth and challenges, and (c) social value creation in social enterprise research context. Further, we explored that researches on social value creation (Cluster 5) have been popular compared with other clusters. However, citation records clearly demonstrate that Cluster 2 and Cluster 6 are not much influential.

Thematic Analysis
We thematically analyzed data to evaluate how the research on the notion of sustainability has been researched in social enterprise context. We found that the concept has been intensively researched and evolved based on six diverse themes as follows: Sustainability as a scope defining criteria in social enterprises. Sustainability has been viewed as a main dimension in defining why the social enterprises exist (Al-Qudah et al., 2022;Picciotti, 2017). As defined by number of scholars, the core purpose of these enterprises is to combat with wicked social issues such as rural poverty, gender discrimination, youth poverty etc with the purpose of creating a tangible impact on the broader society and environment (Jenner, 2016;Koe Hwee Nga & Shamuganathan, 2010). Interestingly, from SE research context, sustainability has been analyzed and viewed within three diverse perspectives-societal (Maseno & Wanyoike, 2022;Palakshappa & Grant, 2017), economic (Sunio et al., 2020), and environmental (Keech, 2017). First, literature on societal sustainability mainly demonstrates that creating a tangible impact on the society has been the main purpose for SEs to exist (Mason, 2012). Second, sustainability is widely investigated in terms of building financially viable social enterprises as a prime scope defining criteria (Rahdari et al., 2016). Here, the main focus is deviating from traditional non-profit dependency models and creating own business models and commercial arms to generate cash the social enterprises need to sustain their own social missions (Young & Kim, 2015). Third, environmental sustainability has been discussed in a broader manner as a scope defining criteria of social enterprises which emphasizes the significance of creating positive environmental  (2010) Journal of Social Entrepreneurship 228 Blundel and Lyon (2015) Journal of Social Entrepreneurship 68 Dees et al. (2004) Stanford Social Innovation Review 474 Smith and Stevens (2010) Entrepreneurship and Regional Development 349 Roper and Cheney (2005) The international journal of business in society 376 Fletcher (2006) Entrepreneurship  & Clifford, 2007). However, our analysis affirms that societal and financial sustainability have been always gained the priority while investigations are limited on environmental aspect.
Sustainability as a tension creating criteria-managing hybridity. Our second theme indicates the criteria used by extant literature to define the scope of social enterprises where social and financial sustainability aspects are broadly discussed (Smith et al., 2013;Zeng et al., 2022). Thus, creating a clear departure from for-profit organizations, social enterprises social enterprises have to engage with managing two conflicting interests: delivering a tangible impact on the society while incubating sustainable business models to stay financially viable. It is evident that these two conflicting interests insist social enterprises to keep a balance between these two diverse extremes causing managerial tension which is vastly researched under the dimension "managing hybridity" (Battilana et al., 2013;Doherty et al., 2014;Svensson & Raw, 2022). Extant literature largely views that understanding this tension is a key criterion to understand the true nature of social enterprises (Smith et al., 2013). It is interesting to see that even this tension has been discussed in diverse manner in the extant literature. First, growing body of literature discusses the tension created due to ensuring two diverse types of sustainability criteria-social and financial (Edery, 2006). Second, extant literature discusses broader antecedents creating this tension such as internal organizational dynamics such as organizational structures, staffing, and internal organizational culture (Gonçalves et al., 2016) and external organizational dynamics such as dynamic operational environment and macro level environment (Battilana et al., 2013). Third, the extant literature also discusses on strategic perspective of managing this tension. In this approach, basically inculcating effective management practices have been discussed (Battilana et al., 2013) while creating sound internal organizational cultures has also been researched (Cooney, 2011). However, we found that the first theme is a very popular among social enterprise research agenda while the second and third has not been received sufficient attention and thus, investigations are lacking in the particular areas which hinder the progression of knowledge creation in social enterprise research domain.
Antecedents driving sustainability. Social enterprise is a strategic tool for community empowerment (Desiana et al., 2022;Finlayson & Roy, 2019). Sustainability as a strongly embedded criterion in social enterprises, has been researched from different perspectives. The third theme explored is the "antecedents driving sustainability." Interestingly, there is a growing body of literature on which factors drive sustainability. Broadly, the large majority of research focuses on internal organizational dynamics on enhancing sustainability such as being mission-oriented (Weerawardena & Mort, 2006), long term orientation (Ghalwash et al., 2017), survival competencies (Ince & Hahn, 2020), nurturing innovations (Tortia et al., 2020), enhancing dynamic learning capabilities (Del Giudice et al., 2019), organizational structural adjustments (Teasdale et al., 2013), and leadership (Puumalainen et al., 2015). Among these all mentioned antecedents, two perspective antecedents-innovation orientation and enhancing dynamic capabilities have been widely researched while other perspectives have received marginalized attention in social enterprise research agenda. First, extant literature largely views that social enterprises have to be socially innovative to maximize sustainable social value creation (Hlady-Rispal & Servantie, 2018). Investigating deeper into the construct, number of empirical studies can be seen on inculcating innovation-favorable organizational culture and diverse management strategies specific for social enterprises (Del Giudice et al., 2019). Extending the social innovation research agenda further, number of investigations can be seen on demonstrating different types of social innovations that social enterprises can inculcate as a strategic approach to enhance sustainability. Here, researchers have attempted to develop typologies of social innovations (Chan et al., 2017) and measurement scales to empirically measure social innovations (Lall, 2017). Second, emerging body of literature could be seen on enhancing dynamic capabilities as a strategic response to enhancing sustainability in social enterprises. Among these research, market learning capability (Cheah et al., 2019), internal learning capability (Westlund & Gawell, 2012), effective network capability (Littlewood & Khan, 2018), survival competencies (Diochon & Anderson, 2009) are the popular dynamic capabilities researched in social enterprise research agenda. However, considering all these research, it is evident that limited investigations could be seen on other specified capabilities which are identified as crucial for building sustainable social enterprises.
Measurement issues in sustainability. Unlike in for-profit context, measuring the impact is relatively puzzling in social enterprises since the prime goal for these ventures is not the wealth accumulation but delivering a social mission unaddressed by the public or the private sectors. Thus, it is imperative to evaluate the significance of measuring mechanisms to measure the impact created by these ventures. The measurement of social impact plays a vital role in helping firms to understand what extent their social mission has been achieved (Arena et al., 2015;Graikioti et al., 2022;Islam, 2020b). On the other hand, social enterprises work with diverse stakeholders such as donors, funders, community, beneficiaries, government and non-governmental organizations and it is vital for them to realize whether the enterprises have delivered the expected outcomes (Arena et al., 2015;Moizer & Tracey, 2010). Thus, the fronts created the urge of having real life measures to assess the outcomes that social enterprises create. Embarking on this front, a number of researchers has attempted developing scales to measure the sustainability outcomes that social enterprise produce at their operations (e.g., performance measurement system, and ecosystem growth strategy). Most widely accepted and applied measurements are performance measurement system (Arena et al., 2015), social impact assessment (Grieco et al., 2015) and ecosystem growth strategy (Han & Shah, 2020;Islam, 2020a). The salient feature of these measures is that they lack the uniformity on different fronts. First, social enterprises work with heterogeneous set of stakeholders, sometimes with conflicting interests and their expectant outcomes are diverse (Arena et al., 2015). Second, operational scopes of social enterprises widely differ and thus, the expectant performances they are supposed to deliver differ and this could lead for having uniformity issues in measurement items (Arena et al., 2015). This diversification can lead to different information needs, different expectations from stakeholders, and also different possible metrics for evaluating SE performances (Arena et al., 2015), making difficult to define a unique framework that could be applied to any SE in any specific field or context.

Sustainability as an embedded criteria in venture life cycle.
Sustainability has been a core dimension in social enterprise research agenda in discussing their life cycle management issues. It is vital that different life cycle stages require diverse strategic needs in any venture (Jayawarna et al., 2020). Forprofit literature has given specific attention on management challenges within specific venture life cycle stages (Spear et al., 2009;Wang et al., 2015). Aligned with for-profit literature, social enterprise literature also discusses diverse strategies that social enterprises have to follow, however with the proposition that sustainability as a strongly embedded criterion in venture life cycle. However, most of the researches are on preserving sustainability in the start-up social enterprises and there is a huge knowledge lacuna on other stages of venture life cycle and how sustainability concept can be preserved while they are progressing in their journey to the growth and declining stages. The general lament is that social enterprises gradually lose their mission orientation and sustainable orientation when they grow which is defined as "marketization" (Javed & Yasir, 2019;Yang & Wu, 2015). Here, what happens is that when these ventures grow, they begin to act based on market signals as mere for-profit ventures which disturbs the core purpose of their existence (Fotheringham & Saunders, 2014;Stecker, 2014). Thus, new knowledge is very much needed in the area of how sustainability could be preserved while social enterprises are scaling up to their next levels of life cycle.
Sustainability as an embedded component in resourcing in social enterprises. All types of ventures are highly constrained with the prevailing resources and neither the social enterprises are exceptional. However, social enterprises are further constrained with the resources since their main focus is not to invest on infrastructure on increasing the wealth accumulation (Stecker, 2014;Tian et al., 2022). Thus, social enterprise context specific literature proposes different strategies for resourcing where sustainability has been at the core. Some of these resource-based researches have borrowed theories such as resource bricolage from for-profit context and contextualized the theories to predict social enterprise research context (Ladstaetter et al., 2018). Further, rather than competing with each other just as for-profit organizations, social enterprise research suggests "co-petition" which emphasizes the need of strategizing for resources by building effective connections with other social enterprises in the field (Littlewood & Khan, 2018). These approaches are also widely identified as sustainable approaches to gain financial, human and knowledge resources that social enterprises cannot produce in-house.

Conclusion
Having identified the impending contribution toward socioeconomic development, investigations on social enterprises are getting ever more widespread in business research agenda. On the other hand, since "sustainability" is a strongly embedded concern for social enterprises to exist, it is apparent that "sustainability" has been a widely used term (almost a taken for granted term or largely has been used a synonym) in social enterprise research context. However, going through the literature raises the question whether "sustainability" is consciously used in social enterprise research or just a taken for granted word. Based on this ground, this paper intended to critically review the extant literature on how the notion of "sustainability" has been researched in social enterprise research domain. In other words, this paper intended to explore to which degree the extant investigations have attempted to consciously use the term "sustainability" in social enterprise research setting. For this purpose, 136 research papers were reviewed, categorized, and coded to present the discussion in a systematic way. Overall, sustainability concept has been researched in social enterprise context from diverse perspectives. In principle, we discovered six themes on which the sustainability has been researched in social enterprise research context namely: (a) sustainability as a scope defining criteria in social enterprises, (b) sustainability as a tension creating criteria-managing hybridity, (c) antecedence driving sustainability, (d) measurement issues in sustainability, (e) sustainability as an embedded criteria in venture life cycle, (f) sustainability as an embedded component in resourcing. Some themes (e.g., theme 1) are heavily grounded on the concept "sustainability" while few themes need more academic scrutiny. As discussed earlier, we contribute to the extant stock of knowledge by exploring the miscellaneous themes through which sustainability has been researched. Contributing to the extant body of knowledge further, in the next section, we identified number of research gaps that future researchers can address.

Future Research Directions
To sum up, we observed several knowledge gaps in extant literature on diverse fronts which are summarized in Table 3. Future researches can focus on the knowledge gaps specified in Table 3 and those gaps would directly lead to enhance social enterprise specific stock of knowledge.
To sum up, we mainly contribute to social enterprise context specific literature by organizing the existing literature. The core purpose of this endeavor was to bring about important knowledge gaps that future researchers can focus on to advance the current social enterprise specific knowledge base.

Acknowledgments
Research team gratefully acknowledge the financial support of the World Bank AHEAD -DOR Project and Uva Wellassa University of Sri Lanka.

Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research work was funded by the World Bank AHEAD project. Herein, as authors, we gratefully acknowledge the financial support of the World Bank AHEAD -DOR Project and the Uva Wellassa University

Ethics Statement
Ethics statement (including the committee approval number) for animal and human studies. If this is not applicable, please state this instead. This article is a literature review and not related in any human or animal studies. Therefore the approval or ethical clearance is not applicable accordingly The scope of sustainability research has to be enhanced and widened since the concept is strongly embedded with the core purpose of existence of these ventures. Thus, there are limited attempts on how sustainability can be preserved throughout the business process and practices of social enterprises.

Research context
Most of the researches have been carried out in developed nations especially in European countries (e.g., Spear et al., 2009) Considering the current overall stock of knowledge, a significant contribution has been made from the experience of developed country perspectives. The lack of investigations from developing country perspectives certainly has limited the context specific knowledge since nature of operations, nature of enterprises could be vastly different based on country perspectives. However, the recent trend shows that the knowledge is emerging from developing country perspective as well specifically from the Asian and African regions in the world.

Research methods
The large majority of papers have followed qualitative research approaches to explore the concept (e.g., (Del Giudice et al., 2019). Conceptualizing and theorizing of the concept are quite common in the research field (e.g., Agafonow, 2019). However, the research increasingly embraces quantitative techniques to empirically measure the theorizations and conceptualization (Graikioti et al., 2022) Empirical validation of the theoretical models is significant to advance the context specific knowledge.

Research sectors
Most of the research has been carried out in niche areas such as age care and child care (Claver, 2005).
Social enterprises operate in diverse markets and it is important to understand them from the operational diversity perspective and thus, future researchers can enhance the understanding by researching on social enterprises operate in diverse areas. Theory borrowing versus social enterprise context specific theory building Researches have borrowed theories from forprofit context to understand social enterprise context (e.g., Wry & York, 2017) while some have attemted on building context specific literature (Tian et al., 2022) Building context specific models and theories are important to enhance social enterprise specific understanding.