A thorough investigation into indoor photovoltaic (PV) cell technologies, carried out by an international team of researchers, has unveiled a wide array of over 250 commercial and laboratory devices. These devices span a broad spectrum of indoor PV technologies, encompassing organic, dye-sensitized, perovskite, as well as crystalline and amorphous silicon, III-V semiconductor, chalcogenide, and emerging lead-free alternative cells.
According to co-author Giulia Lucarelli, the interest in this field has been rapidly growing, prompting the team to conduct a comprehensive review of all indoor PV technologies. The researchers also explored the applications, recent advancements, and strategies for designing more stable, highly efficient cells that can operate at very low light levels.
The review also includes a detailed analysis of the performance of indoor PV devices at illuminance levels of 200 lx and 1000 lx. Corresponding author Thomas M. Brown emphasized that most homes have a 200 lx illuminance, while 1000 lx is typical in well-lit environments such as supermarkets. Brown also noted that one of the initial high-demand market niches for indoor PV has been in electronic supermarket shelf labels, with other applications emerging in the Internet-of-Things sector.
The review covered a wide range of cell technologies, including crystalline and amorphous silicon, III-V semiconductor, chalcogenide, organic, dye-sensitized, perovskite, and lead-free alternative devices. The team also made significant observations regarding the power conversion efficiency (PCE) and maximum power density (MPD) of these technologies, noting the superior performance of perovskite solar cells across various indoor lighting conditions.
Furthermore, the researchers discussed the need for standardized performance reporting, particularly with regard to the light source spectrum and illuminance levels. They emphasized that reporting MPD for varying illuminance levels is crucial for product developers designing energy harvesting solutions.
The team also highlighted the diverse range of indoor lamp spectra, from LED to compact fluorescent and lamp bulbs with different color temperatures. They also underscored the necessity to establish stability protocols for indoor PV technologies and conduct further investigations under continuous indoor illumination.
In conclusion, the team emphasized the importance of enhancing the performance, stability, and cost-effectiveness of indoor PV devices, as well as their integration capabilities with electronic products. They also discussed the ongoing developments in perovskite PV indoors and the utilization of more sustainable materials and fabrication processes.
The comprehensive review, titled “Photovoltaics for Indoor Energy Harvesting,” is published in Nano Energy. The researchers involved in this study were from prominent institutions such as Tor Vergata University in Italy, the Netherlands Organization for Applied Scientific Research (TNO), FundaciĆ³n Escuela Tecnologica in Colombia, and Jain University in India.
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