Molecular engineering of dye-sensitized solar cells (DSCs) has catalyzed a paradigm shift in indoor photovoltaics (IPV), enabling the realization of self-powered, intelligent Internet of Things (IoT) devices. Through synergistic co-sensitization of XY1 and L1 dyes, power conversion efficiency has surged from 29.0% to 38.0% under 1000 lux fluorescent illumination [1,2]. Precise tailoring of the Cu(II/I)(tmby)2 electrolyte, with Cu(II) concentration optimized to 0.06 M, has yielded an exceptional open-circuit voltage of 0.995 V and short-circuit current density of 147 µA cm-2[2].  

Interfacial dynamics, probed via photoinduced absorption spectroscopy, have revealed efficient dye regeneration even at near-zero driving force, challenging established electron transfer theories [2]. Electrochemical impedance spectroscopy has elucidated the critical role of Lewis bases in modulating TiO2conduction band energetics and recombination kinetics [2,3]. This molecular-level understanding has facilitated the evolution from liquid electrolytes to solid-state hole conductors, culminating in "zombie" cells that retain efficiency post-electrolyte solidification [1,4]. Scalability has been demonstrated with 3.2 cm2 active areas maintaining 37.1%, 34.8%, and 33.7% efficiencies at 1000, 500, and 200 lux, respectively [2].  

The seamless integration of these advanced IPV cells with microelectronics has propelled IoT capabilities from basic wireless communication to sophisticated on-device machine learning. A 7-cell array (22.4 cm2) now powers an ESP32 microcontroller executing Long Short-Term Memory (LSTM) neural networks, achieving 93.5-100% accuracy in deployment scenario prediction and performing up to 0.560 VAX MIPS [2,5].  

This multidisciplinary synergy - from molecular design to materials engineering, device optimization, and edge computing implementation - exemplifies the transformative potential of chemistry-driven innovation in sustainable technology. The convergence of diffuse light harvesting and artificial intelligence paves the way for autonomous, energy-efficient IoT ecosystems with far-reaching implications for smart infrastructure and sustainable digital transformation.  

[1] Michaels et al., Chem. Sci., 2020, 11, 2895-2906.  

[2] Michaels et al., Chem. Sci., 2023, 14, 5350-5360.  

[3] Zhang et al., Nat. Commun., 2021, 12, 1777.  

[4] Cao et al., Nat. Commun., 2017, 8, 15390.  

[5] Freitag et al., Nat. Photonics, 2017, 11, 372-378. 

Professor Marina Freitag is a Royal Society University Research Fellow and Chair of Energy at Newcastle University. Her pioneering work on dye-sensitized solar cells and indoor photovoltaics has established her as a leader in sustainable energy research. With a Ph.D. from Rutgers University and experience at EPFL and Uppsala University, Prof. Freitag has consistently advanced the field of solar energy conversion. 

Her research focuses on developing highly efficient, sustainable photovoltaic technology for powering AI-based Internet of Things devices. Prof. Freitag's innovations have led to record-breaking efficiencies in ambient light conditions, pushing the boundaries of what's possible in low-light energy harvesting. 

With prestigious accolades like the 2022 Royal Society of Chemistry Harrison-Meldola Memorial Prize and Göran Gustafsson Young Researcher Award 2019, Prof. Freitag's contributions to renewable energy are invaluable. Freitag's commitment extends beyond academia, engaging the public through various outreach workshops and exhibitions, nurturing a broader understanding and adoption of renewable energy solutions.  

Prof. Freitag's multidisciplinary approach, combining materials chemistry, device physics, and artificial intelligence, opens new avenues in energy materials research. Her vision of harnessing diffuse light for structured information processing drives the development of autonomous, energy-efficient technologies with far-reaching implications for smart infrastructure and sustainable computing.