All-inorganic non-perovskite copper halides for light emission

Achieving commercially viable luminescent devices requires the design of synthetic materials that are non-toxic, stable, and cost effective. However, despite the tremendous efforts to optimize the synthesis and improve the functionality of conventional semiconductors, the commercial potential and performance of these materials are often compromised. All-inorganic copper halides, which are characterized by an anionic Cu_mX_n framework counterbalanced by inorganic cations, have emerged as potential candidates for next-generation light-emitting devices. Their structural versatility combined with their superior emission performance make them attractive for the development of semiconductor devices realized at low cost. Here, we discuss the current understanding of the structural and photophysical properties of copper halides and present recent advances in their integration into devices and critical issues for realizing next-generation semiconductor devices for optoelectronics.