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What if the key to a more sustainable future was already in our homes? New research from the School of Sustainable Energy Engineering (SEE) explores how emerging materials for solar technology can sustainably generate electricity from indoor light.

The project was led by SEE professor Vincenzo Pecunia and postdoctoral fellow Charlotte Clegg from the  with contributions from Jianjun Mei and collaborators Aitana Uclés Fuensanta and Taofeeq Ibn-Mohammed from the University of Warwick. Their insights are detailed in  in Materials Science and Engineering: Reports.

The technology in focus, known as indoor photovoltaics, is designed to harvest energy from artificial light sources such as common light bulbs and LEDs. It offers an alternative method to sustainably power smart devices without relying on disposable batteries.

“With our world becoming increasingly connected, powering smart devices has become a growing challenge” says professor Vincenzo Pecunia. “Right now, most of these devices are powered by disposable batteries, which need regular replacement and generate significant waste. Harvesting energy from indoor light provides a greener alternative and may be the key to unlocking the full potential of the Internet of Things—which itself enables countless sustainability-focused applications.”

The advent of perovskites, a family of emerging materials studied by professor Pecunia and his team, has made indoor photovoltaics more efficient and affordable. These materials have demonstrated unprecedented performance in harvesting indoor light.

“Perovskites have shown record-breaking efficiency, up to four times higher than conventional technologies,” explains Pecunia. “They have the potential to help address the practical, cost, and environmental challenges of traditional batteries, while contributing to a more sustainable and higher quality of life.”

Despite the benefits that perovskites offer for improving indoor photovoltaics, the most efficient perovskites contain lead—a well-known toxic chemical element. This has prompted researchers to explore alternatives, assuming lead-based options are environmentally harmful. The study conducted by Pecunia and his team challenges this common perception, offering a new perspective.

The team developed a framework to compare the environmental impact of indoor photovoltaics and disposable batteries, identifying the most sustainable materials and designs. Instead of focusing only on composition, the team investigated the full life cycle of indoor photovoltaics based on perovskites and their associated environmental impact.

The study revealed that top-performing indoor photovoltaics can offset their environmental cost within weeks. This could not only reduce waste and battery pollution but also improve the sustainability of the smart device ecosystem. The results also uncovered that many lead-free alternatives showed a lower overall environmental performance, with some containing other materials that also pose environmental concerns. Despite containing lead, some lead-based perovskites have proven to be more environmentally friendly over their life span—particularly under controlled deployment and use scenarios.

 “To our own surprise, our findings show that lead-free does not necessarily mean greener,” says Pecunia. “In order to develop technology that is truly sustainable, we need to look beyond labels and examine the full impact from start to finish. That shift in thinking could reshape how we design the next generation of energy-harvesting devices.”

While the conventional wisdom in the scientific community to date has been that lead-free indoor photovoltaics are the more sustainable option, Pecunia’s study revealed that they may pose a greater environmental burden than their lead-based counterparts. These findings highlight that it is time to challenge this preconceived assumption, prompting the team to encourage policymakers and industry leaders to implement regulations that reflect the full life cycle impacts of this energy harvesting technology.

Given the novelty of indoor photovoltaics, the team is seeking to improve the long-term stability of the devices and engineer their composition to enhance their performance. They will continue advancing research to develop cleaner solutions to power smart devices—supporting sustainability-focused applications like smart homes, smart manufacturing, and beyond.