Special Section Guest Editorial: Introducing the Special Section on Thermophotovoltaic Systems

The concept of thermophotovoltaics (TPV), converting heat into electricity via photovoltaic cells, originated in the 1960s, yet very recently the field has experienced significant advances.Thanks to breakthroughs in nanofabrication, materials science, and instrumentation, TPV technology is emerging as a viable solution for sustainable energy production, with strong connections to photovoltaics and other renewables, as well as thermal energy storage.The integration of highquality III-V semiconductor materials and innovative photovoltaic (PV) cell designs has reignited scientific interest and increased the market potential of TPV systems.At the core of this resurgence is the ability to precisely control thermal radiation, a feat that connects disciplines such as nanophotonics, semiconductor physics, and materials science.By tailoring thermal emission, researchers can optimize TPV performance, making these systems more efficient and versatile.Thermophotovoltaics show promise in both large-scale energy storage and recycling low-grade waste heat.By using TPV technology, stored high-temperature heat can be converted into electricity during periods of low energy supply, while TPV systems also provide a means to directly harness solar heat.The field's maturation is evident in the formation of a global research community, as seen in international conferences like the recent 15th World Conference on Thermophotovoltaic Generation of Electricity, held in Madrid, Spain, from 30 September to 3 October 2024.With increasing focus on tackling the world's energy demands sustainably, TPV research is shifting into a new era.The current issue of Journal of Photonics for Energy (JPE) features a Special Section on Thermophotovoltaic Systems, to highlight fundamental and applied advancements, spanning topics from thermal emission materials and photon management to novel TPV applications in space and waste heat recovery.This renewed momentum underscores the potential of thermophotovoltaics to play a key role in a more energy-efficient future, driving innovation across multiple sectors.The convergence of TPV technology with other emerging energy solutions offers a glimpse of an exciting path forward in the pursuit of sustainable energy alternatives.In this JPE special section, a techno-economic analysis of a solar thermophotovoltaic system for a residential building is provided by Manish Mosalpuri, Fatima Toor, and Mark Mba-Wright.They predict a decrease by $0.128/kWh in levelized cost of consumed electricity with the employment of residential TPVs, showcasing the feasibility and technological relevance of TPVs.New findings in materials design are also reported, for example in the work