| Work Detail |
A team of researchers in India has improved the power conversion efficiency and stability of indoor dye-sensitized solar cells based on cosensitized organic dyes. The best indoor photovoltaic devices achieved 40% efficiency under 4000 lux fluorescent illumination and 10.40% under standard AM 1.5G illumination from one sun.
A group of scientists led by Indias National Institute of Interdisciplinary Science and Technology (CSIR-NIIST) claim to have enhanced the stability and efficiency of dye-sensitized solar cells for indoor photovoltaic applications.
This type of solar cell, also known as a Grätzel solar cell after its inventor, EPFL professor Michael Grätzel, is used to power indoor electronic devices such as wireless sensors or the Internet of Things.
“Our study introduces a significant advancement in dye-sensitized solar cells (DSCs) by utilizing star-shaped triphenylamine dye cocktails with a rigid triple-bond conjugated p-backbone. This molecular design enhances the light-harvesting capability in the visible region, providing excellent overlap with indoor light spectra,” corresponding author Suraj Soman told pv magazine , noting that the design incorporated an asymmetric dual-species copper(II/I) electrolyte that had been introduced in previously published research by the group.
The team developed the cell with a novel star-shaped triphenylamine sensitizer (RJ-C6) that was combined with the XY1b dye and its own dual-species asymmetric copper (II/I) electrolyte. “The precise structural design of the dyes promotes synergistic effects, allowing for efficient molecular packing, higher dye loading, and improved visible light absorption,” Soman adds. “In addition, this configuration creates a strong barrier against recombination and back electron transfer.”
The most challenging aspect of the research was identifying the ideal combination of dyes for cosensitization. “Small variations in molecular structures, such as altering the length of alkyl chains or incorporating triple bonds, can profoundly affect photovoltaic performance under low-intensity indoor light. Achieving optimal packaging of the dye in the semiconductor (TiO2) is critical,” says Soman.
The combinations of dyes, electrolytes, semiconductor porosity and device architecture that work well under indoor light differ significantly from those optimized for standard sunlight conditions. “Customizing all of these parameters specifically for indoor applications was the key to our success,” Soman explains.
The best-performing devices exhibited panchromatic absorption spanning the entire spectrum of fluorescent light. According to the researchers, they achieved 35% below 100 lux, 37% below 1000 lux, and a record 40% efficiency below 4000 lux, which they say brings DSCs one step closer to being used as an “attractive candidate for indoor photovoltaic applications.”
The cell also achieved 10.40% efficiency under standard AM 1.5 G solar radiation, and 40% power conversion efficiency under warm white compact fluorescent lamp (CFL) indoor lighting.
In terms of stability, the academics reported that the RJ-C6:XY1b cosensitized devices demonstrated “promising stability” in accelerated indoor stability tests, with no degradation even after 800 hours.
The cell measures 1.5 cm2 and has an active area of ??0.32 cm2. The scientists noted that two of them combined in series with an active area of ??0.68 cm2 could power a clock and a temperature sensor under 1000 lux CFL illumination.
“These advances present a sustainable alternative to conventional primary batteries, potentially reducing the environmental impact of millions of discarded batteries contributing to landfills,” Soman said.
There are plans to take the technology out of the lab and into practical indoor and outdoor photovoltaic applications. “We are working on developing self-powered devices without batteries, and some innovative products are already being tested in the field. In addition, we are extending our research to building-integrated photovoltaics (BIPV) by developing coloured semi-transparent solar cells, with the aim of integrating aesthetics and functionality into energy-efficient buildings,” explains Soman.
The design and research details appear in “ Enhanced indoor photovoltaic efficiency of 40% in dye-sensitized solar cells using cocktail starburst triphenylamine dyes and dual species copper electrolyte,” published in the Journal of Materials Chemistry A. The team also includes scientists from the Academy of Scientifc and Innovative Research (AcSIR), and the National Institute of Technology Uttarakhand (NITUK). |
