Recent breakthroughs in lead-free perovskite nanocrystals

Over the past decade, lead halide perovskite nanocrystals (LHP NCs) have garnered remarkable attention for optoelectronic applications, thanks to their exceptional optical and electrical properties. However, the environmental and health risks associated with lead, along with the poor chemical stability of LHPs under harsh conditions, substantially limit their practical application in emerging fields.To address these issues, different types of lead-free perovskite (LFP) NCs have recently emerged. This article comprehensively reviews all categories of LFP NCs, highlighting their simulation- driven band structures, and detailing how recent modificationtechniques have improved their optoelectronic properties and environmental stability. The immense potential of LFP NCs across a broad spectrum of practical applications, ranging from optoelectronics and photovoltaics to biosensing, biomedicine, and energy conversion systems, is presented and critically reviewed. Finally, future research directions, technological advancements, and commercialization trends are discussed in detail.