The Quest for Low Work Function Materials: Advances, Challenges, and Opportunities

Low work function (LWF) materials are essential for enabling efficient systems’ behavior in applications ranging from vacuum electronics to energy conversion devices and next-generation opto-electronic interfaces. Recent advances in theory, characterization, and materials engineering have dramatically expanded the candidates for LWF systems, including alkali-based compounds, perovskites, borides, nitrides, barium and scandium oxides, 2D materials, MXenes, functional polymers, carbon materials, and hybrid architectures. This review provides a comprehensive overview of the fundamental mechanisms governing the work function (WF) and discusses the state-of-the-art measurement techniques, as well as the most used computational approaches for predicting and validating WF values. The recent breakthroughs in engineering LWF surfaces through different methods are discussed. Special emphasis is placed on the relationship between predicted and experimentally measured WF values, highlighting the role of surface contamination, reconstruction, and environmental stability. Performance, advantages, and limitations of major LWF material families are fully analyzed, identifying emerging opportunities for next applications. Finally, current and fundamental challenges in achieving scalable, stable, and reproducible LWF surfaces are considered, presenting promising research directions such as high-throughput computational discovery and in situ surface engineering with protective coatings. This review aims to provide a unified framework for understanding, achieving, and advancing LWF materials toward practical and industrially relevant technologies.