On the path toward independence from fossil fuels, solar energy is the most promising solution, but it needs a robust and reliable storage system to face its intrinsic fluctuations due to location, day cycle, and weather. The integration between energy harvesting and storage (H&S) technologies is a must toward clean energy production, and it becomes even more appealing considering the possibility of producing electricity not only from direct sunlight but also from diffuse light and indoor illumination. Herein, a dye‐sensitized solar module (DSSM) developed to harvest indoor illumination and directly store it into an electrical double‐layer capacitor (EDLC) is presented. Five series‐connected dye‐sensitized solar cells are fabricated on the same substrate and the module is integrated with a high‐voltage EDLC. The integrated device is characterized under indoor light sources such as light emitting diodes and fluorescent lamps. The results show one of the highest efficiencies ever reported for a high‐voltage DSSM under indoor illumination (16.27%), the largest voltage window ever reported for an indoor H&S device based on DSSM and EDLC—up to 3 V—and an overall photoelectric conversion and storage efficiency of 9.73% under indoor illumination.

A significant portion of the billions of Internet of Things (IoT) smart devices operate indoors, typically powered by batteries that require periodic recharging or disposal, raising sustainability concerns about maintenance and electronic waste production. This has generated increased interest in developing indoor photovoltaics (IPV) for self‐rechargeable IoT devices. Among IPV technologies, dye‐sensitized solar cells (DSSCs) offer high conversion efficiency, stability, and scalability. However, the use of toxic and flammable solvents, such as acetonitrile (ACN) and 3‐methoxypropionitrile (MPN), remains a concern. This research investigates γ‐valerolactone (γ‐VL), a sustainable, low‐toxic solvent derived from cellulosic biomass, as an alternative for DSSC electrolytes. Electrolytes based on I ⁻ /I ₃ ⁻ redox shuttle are prepared with γ‐VL, MPN, and ACN and studied in both dummy cell and full device configuration. Results show that γ‐VL is unsuitable for outdoor DSSCs due to slower ion diffusion and reduced I ₃ ⁻ reduction at the counter electrode. However, γ‐VL DSSCs outperform those using ACN and MPN under indoor light, demonstrating equivalent short‐circuit currents but higher open‐circuit voltages, improved fill factors, and enhanced overall efficiency, enabled by lower recombination at the photoanode. These findings position γ‐VL as a promising, eco‐friendly option for DSSC electrolytes in indoor IoT applications.

With the rising levels of atmospheric CO₂, electrochemistry shows great promise in decarbonizing industrial processes by converting CO₂ into valuable products through scalable and sustainable technologies. In this framework, the present study investigates the solar-driven CO₂ reduction toward carbon monoxide, achieved by the integration between the electrochemical reactor and dye-sensitized solar cells (DSSCs), both in experimental and modeling perspectives. COMSOL^® Multiphysics 6.3 was used to develop a detailed finite element method model of the electrochemical cell integrated with a photovoltaic module, validated with the experimental results that demonstrated a strong correlation. A 2D model was designed, incorporating cathode and anode regions divided by an ion-exchange membrane. The model includes platinum foil and silver nanoparticles as catalysts for the oxygen evolution reaction and CO₂ reduction reaction, respectively. Integration with the fundamental equations of the DSSCs was simulated to analyze the solar-driven CO₂ reduction behavior under solar irradiance variations, offering a valuable tool for optimizing operating conditions and predicting the device performance under different environmental conditions. The integrated device successfully produces CO with a faradaic efficiency of 73.85% at a current density of J = 3.35 mA/cm² under 1 sun illumination, with the result validated and reproduced by the mathematical model. Under reduced illumination conditions of 0.8 and 0.6 suns, faradaic efficiencies of 68.5% and 64.1% were achieved, respectively.