Researchers at The Australian National University (ANU) have achieved a new record efficiency for low-cost semi-transparent perovskite solar cells in a breakthrough that theu say could bring down the cost of generating solar electricity.
The team led by The Duong from the ANU Research School of Engineering have achieved over 26 percent efficiency in converting sunlight into energy, by mechanically combining perovskite with silicon solar cells.
In their paper 'Rubidium Multication Perovskite with Optimized Bandgap for Perovskite-Silicon Tandem with over 26 percent Efﬁiciency' in Advanced Energy Materials, the team explain how Rubidium doping improves the crystallinity and suppresses the defect migration in the 1.73 eV band gap perovskite. This leads to improvements in cell performance and light stability.
They made a semi-transparent perovskite cell with a steady-state efficiency of 16 percent and average transparency of 84 percent between 720 and 1100 nm. By combining it with a 23.9 percent silicon cell, they obtained an efficiency of 26.4 percent (10.4 percent from the silicon cell) for the four terminal tandem cell. This is very close to the current record for a single junction silicon cell of 26.6 percent.
After several cycles of 12 hours of light/dark, the cell retains 90 percent of its initial efficiency.
"Until now efficiencies of this kind have only been achieved using high cost materials normally used on satellites," said Duong, a PhD student. "We are now a step closer to a low cost alternative."
The research is supported by $3.6 million in funding from the Australian Renewable Energy Agency.
Kylie Catchpole, a professor from the ANU Research School of Engineering said the advances in solar technology were good news for consumers, although the perovskite cells were not yet ready for use on rooftops.
"This breakthrough opens the way to increasing the efficiency of silicon solar cells further, and in a cheap way," she said.
"The key challenge for now is achieving the same stability as we have with silicon solar cells that can be put out on a roof for 20 years using perovskite.
"Over the next few years we are planning to increase efficiencies to 30 percent and beyond."
This work was part of the 'High-efficiency silicon/perovskite solar cells' project led by University of New South Wales with research partners ANU, Monash University, Arizona State University, Suntech R&D Australia Pty Ltd and Trina Solar.