Room‐temperature plastic inorganic semiconductors for flexible and deformable electronics

Flexible electronics ushers in a revolution to the electronics industry in the 21st century. Ideally, all components of a flexible electronic device including the functional component shall comply with the deformation to ensure the structural and functional integrity, imposing a pressing need for developing room‐temperature strain‐tolerant semiconductors. To this end, there is a long‐standing material dilemma: inorganic semiconductors are typically brittle at room temperature except for size‐induced flexibility; by contrast, organic semiconductors are intrinsically soft and flexible but the electrical performance is poor. This is why the discovery of bulk plasticity in Ag2S at room temperature and ZnS in darkness is groundbreaking in solving this long‐standing material dilemma between the mechanical deformability and the electrical performance. The present review summarizes the background knowledge and latest advances in the emerging field of plastic inorganic semiconductors. At the outset, we argue that the plasticity of inorganic semiconductors is vital to strain tolerance of electronic devices, which has not been adequately emphasized. The mechanisms of plasticity are illustrated from the perspective of chemical bonding and dislocations. Plastic inorganic materials, for example, ionic crystals (insulators), ZnS in darkness, and Ag2S, are discussed in detail in terms of their prominent mechanical properties and potential applications. We conclude the article with several key scientific and technological questions to address in the future study. Plastic inorganic semiconductors possess large, intrinsic deformability and high electrical performance, holding great promise for next‐generation flexible/deformable electronics. This review summarizes recent advances in room‐temperature plastic nonmetallic inorganic materials, including rock‐salt‐structured ionic compounds, ZnS crystals, and Ag2S. The remarkable plasticity in these inorganic materials is illustrated in terms of chemical bonding and dislocations. Challenges and prospects for this emerging field are also proposed.