Lead (Pb)-free perovskite materials (PMs) have gained attention as a safe substitute for conventional lead-based halide PMs for next-generation optoelectronic applications. These materials offer the key benefits of lead perovskites, such as strong absorption in the visible region, less toxic, environmentally friendly nature, tunableband gaps, and long carrier lifetimes. At present there is an advancement in the synthesis route, such as solution processing, hot-injection methods, and solid-state reactions, which enables researchers to fabricate high-quality thin films and nanocrystals. Due to the toxicity associated with the Pb, the Pb2+ ion is successfully replaced by the Sn2+, Ge2+, Bi3+, Sb3+ ions. Many of these show improved stability against heat, moisture, and photodegradation. Double perovskites are particularly interesting because of their structural properties and tunable optoelectronic behaviour, which make them relevant for solar cells, LEDs, photodetectors, and X-ray detection. But significant hurdles remain. Sn2+ and Ge2+ oxidize readily, some low-dimensional structures exhibit poor charge transport, and device efficiencies still lag behind lead-based benchmarks. This chapter covers the primary synthesis routes, structural characteristics, and optoelectronic behaviour of lead-free perovskites. Recent device improvements are reviewed in this study, and applications across different optoelectronic platforms are discussed, with particular attention to stability enhancement and future pathways toward environmentally friendly, high-performance materials.