Metal halide perovskites have emerged as promising candidates for next-generation optoelectronic technologies, owing to their exceptional physical and chemical properties. The commercialization of perovskite photovoltaics further underscores the potential for advancing perovskite-based light-emitting applications, including phosphors and light-emitting diodes (LEDs). Sustainability—encompassing environmental, economic, and social dimensions—has become an essential criterion for evaluating the long-term viability of emerging technologies. However, mainstream perovskite research has raised public concerns regarding potential toxicity and environ- mental impact, thereby limiting their broader adoption. Herein, this thesis aims to reframe the design strategy for perovskite light-emitting technologies—from materials to devices—through a sustainability lens, while maintaining a solid grounding in their underlying physical mechanisms. The ultimate goal is to develop perovskite phosphor materials and perovskite LEDs (PeLEDs) that achieve both high performance and commercial viability on a sustainable footing.

This thesis undertakes efforts at both materials and device levels for substantiable design of this emerging technology. On the materials side, we develop lead-free double perovskites incorporating earth-abundant lanthanide ions and investigate their photophysical mechanisms. Two key studies are presented: the first builds upon the typical 4f–4f transitions of Eu3+ and enhances its hypersensitive transition channel to achieve efficient, spectrally tunable red emission; the second moves beyond the 4f–4f channels of Gd3+ by enabling Laporte-allowed 5d–4f transitions, resulting in highly efficient, ultrafast blue emission. On the device side, we reframe the design pathway for integration-level PeLEDs, guided by life cycle and techno-economic assessments. This section also comprises two studies: the first evaluates the environ- mental and economic sustainability of current PeLEDs across all emission ranges and proposes actionable upgrading strategies toward industrial readiness; the second builds upon these strategies and focuses specifically on the development of clean, low-cost near-infrared PeLEDs—where sustainability challenges are most severe— targeting market-ready applications. The outcomes presented in this thesis not only deepen the understanding of perovskite light-emission mechanisms but also lay the groundwork for the sustainable commercialization of perovskite light-emitting technologies.