Page 150 - CW E-Magazine (17-6-2025)

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NOVEL CONFIGURATION

IIT-B Centre demonstrates tandem solar cell

with effi ciency greater than 26%

A team at the National Centre for PSC and 16% for a large area
Photovoltaic Research and Educa- (0.805-cm ) PSC.
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tion (NCPRE) at the Indian Institute
of Technology Bombay (IIT-B) has However, the PSC thus fabricated is
fabricated a novel semi-transparent not as stable as a conventional silicon
perovskite solar cell (PSC) and, by solar cell. To address this, the researchers
combining it with a silicon-based turned to tandem device architecture.
solar cell, has demonstrated an Instead of using the PSC by itself, they
effi ciency of more than 26% for such layered it on top of a commercially
a cell. available Passivated Emitter and Rear
Contact (PERC) silicon solar cell. The
Solar energy has become one of Tandem confi guration new tandem structure was far more
the most signifi cant contributors to the The team at IIT-B has overcome the resilient and stable under different
world’s renewable energy goals. How- stability issue by combining their PSC environmental conditions, with a higher
ever, the cost of solar energy remains a with a silicon solar cell in what is called demonstrated effi ciency. Although the
major hurdle to overcome. Though the a tandem confi guration. Combining the PSC could still degenerate faster than
prices of solar panels have dropped signi- two different types of solar cells allows the silicon cell, the fabrication allows
fi cantly in recent years, there is still a the device to convert more of the light for the top PSC layer to be easily
need for more affordable solar energy falling on it into electricity, provides replaced. “In our case i.e. in 4T tandem
solutions to make it truly ubiquitous. greater stability, while lowering overall confi guration when the top low-cost
This is where perovskite solar cells lifetime costs. perovskite solar cells fail, there is a
(PSCs) come in, promising an able possibility to replace the top cells with
alternative to traditional silicon solar “We have fabricated a stable 4T a new one because our tandem device
cells due to their low fabrication costs (four terminal) Si/perovskite tan- is only optically coupled so, it can
and high effi ciency. dem solar cells which provides out- enhance the lifetime of the overall
standing stability in the dark as well devices,” said Prof. Kabra.
Perovskites are any material with a as continuous heating conditions,”
particular crystal structure, usually in said Prof. Dinesh Kabra, a professor The researchers also demonstrated
the form of ABX3, where A, B, and X at IIT-B and an author of the new a very high 26% power conversion
can be atoms or molecules, like calcium study. effi ciency for the tandem device, which is
titanium oxide (CaTiO ). Perovskite one of the highest recorded effi ciencies
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crystals are one of the most abundant For their study, the team fi rst fabri- for such a device. “Since there is huge
types of crystal structure families, with cated a PSC from a thin fi lm of interest in Si/perovskite tandem solar
many compounds with different proper- perovskite, which is transparent to cells, lots of high-effi ciency results are
ties adopting such a crystal structure. near InfraRed light (low-frequency coming from the industry, but do not
Perovskites have gained a lot of atten- light). The transparency makes them reveal the device architecture and it’s
tion since 2009 when the fi rst PSC very useful in several devices, includ- not too useful for academic research
was fabricated. While PSCs are highly ing in building integrated photovoltaic progress. Our report not only shows the
effi cient at converting light into electri- (BIPV), vehicle integrated photovoltaic complete device architecture but also
city and cheap to produce, they lack (VIPV), etc. The PSC was then mea- explains the fabrication process, as a
the stability of conventional solar sured for its power conversion effi ciency typical practice of academic research,”
cells, like the ones made of silicon, and (PCE), which measures the amount Prof. Kabra noted. More importantly,
often degenerate when exposed to light, of light converted into electricity. The the device also lowers the levelised
heat, or applied voltage for extended PSC recorded very high effi ciencies cost of energy (LCOE) for tandem
periods. of 17.1% for a small area (0.175-cm ) solar cells.
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150 Chemical Weekly June 17, 2025

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