Scientists at the National Centre for Photovoltaic Research and Education of the Indian Institute of Technology Bombay (IIT Bombay) claimed to have achieved a power conversion efficiency of more than 26% for a 4 terminal (4T)-silicon perovskite tandem solar cell.

To overcome perovskite stability issues, the IIT research team initially fabricated a transparent perovskite cell to near-infrared and low-frequency light.

The work titled Stable and Efficient Large-Area 4T Si/perovskite Tandem Photovoltaics with Sputtered Transparent Contact is published in the journal RRL Solar.

A 4T tandem device has four terminals, two for each of the tandem device’s layers, allowing precise measurements of the solar cell’s performance while also improving the device’s efficiency and lifetime.

While the perovskite solar cell alone in the experiment exhibited a higher efficiency of 16% for a larger area of 0.805cm2, the teams demonstrated a much higher energy conversion efficiency by layering the perovskite cells atop a commercially available PERC (passivated emitter and rear contact) silicon solar cell.

While perovskite solar cells are highly efficient in converting light into electricity and their production is inexpensive, they lag in performance compared to conventional silicon solar cells. Also, perovskites degrade over time when exposed to direct sunlight for longer durations, directly affecting energy production.

The tandem approach has become the go-to solution to many solar cell studies worldwide as it allows combining both the perovskite and silicon solar cells to attain enhanced efficiency.

“Perovskite solar cells are known for their high-power conversion efficiency and lower production cost; however, they are lagging in terms of their stability. However, in our work, we have fabricated a stable 4T (four terminal) Si/perovskite tandem solar cells which provide outstanding stability in the dark as well as continuous heating conditions,” explained the author of the study Dinesh Kabra.

According to Kabra, “In 4T tandem configuration when the top low-cost perovskite solar cells fail, there is a possibility to replace the top cells with a new one because our tandem device is only optically coupled so, it can enhance the lifetime of the overall devices.”

The levelized Cost of Energy is one of the most crucial factors in energy production as it measures the cost of electricity for different methods of electricity generation.

For example, LCOE can be used to calculate how much one can save on the electricity bill by switching to solar power generation. The researchers found that the device developed with perovskite-silicon tandem solar cells also lowered the LCOE for tandem solar cells.

In a similar research, scientists at the King Abdullah University of Science and Technology claimed to have developed a perovskite-silicon tandem solar cell with a record conversion efficiency of 33.2%.

Last December, IIT Roorkee researchers developed a prototype of a low-cost, high-quality perovskite solar cell that achieved a stable energy conversion efficiency of 17.05%.