Researchers at the Australian National University (ANU) have found a novel way to fabricate high efficiency semi-transparent perovskite solar cells that could lead to more efficient and cheaper solar generated electricity. The research has recently been published in Advanced Energy Materials.
The new fabrication method involves adding a small amount of the element indium into one of the cell layers during fabrication. That could increase the cell's power output by as much as 25 per cent.
This new fabrication method is reported to significantly improved the performance of perovskite solar cells, which can combine with conventional silicon solar cells to produce more efficient solar electricity.
The researchers note that perovskite solar cells are extremely good at making electricity from visible light - blue, green and red - while conventional silicon solar cells were more efficient at converting infrared light into electricity. By combining these two cells, the perovskite cell and the silicon cell, we are able to make much better use of the solar energy and achieve higher efficiencies than either cell on its own. So the prospect of adding a few additional processing steps at the end of a silicon cell production line to make perovskite cells is very exciting and could boost solar efficiency from 25 per cent to 30 per cent.
According to the researchers although perovskite cells can improve efficiency, they are not yet stable enough to be used on rooftops. They point out that the new fabrication technique could help develop more reliable perovskite cells.
The development builds on the state-of-the-art silicon cell research at ANU and is part of a $12.2 million "High-efficiency silicon/perovskite solar cells" project led by University of New South Wales and supported by $3.6 million of funding from the Australian Renewable Energy Agency.
Research partners include Monash University, Arizona State University, Suntech R&D Australia Pty Ltd and Trina Solar.
Dr Tom White said, "The research placed ANU in a small group of labs around the world with the capability to improve silicon solar cell efficiency using perovskites". Tom added, "We have been able to achieve a record efficiency of 16.6 per cent for a semi-transparent perovskite cell, and 24.5 per cent for a perovskite-silicon tandem, which is one of the highest efficiencies reported for this type of cell."
Efficient Indium-Doped TiOx Electron Transport Layers for High-Performance Perovskite Solar Cells and Perovskite-Silicon Tandems
Jun Peng | The Duong | Xianzhong Zhou | Heping Shen | Yiliang Wu | Hemant Kumar Mulmudi | Yimao Wan | Dingyong Zhong | Juntao Li | Takuya Tsuzuki | Klaus J. Weber | Kylie R. Catchpole | Thomas P. White
First published: 4 November 2016 | DOI: 10.1002/aenm.201601768
Abstract
In addition to a good perovskite light absorbing layer, the hole and electron transport layers play a crucial role in achieving high-efficiency perovskite solar cells. Here, a simple, one-step, solution-based method is introduced for fabricating high quality indium-doped titanium oxide electron transport layers. It is shown that indium-doping improves both the conductivity of the transport layer and the band alignment at the ETL/perovskite interface compared to pure TiO2, boosting the fill-factor and voltage of perovskite cells. Using the optimized transport layers, a high steady-state efficiency of 17.9% for CH3NH3PbI3-based cells and 19.3% for Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3-based cells is demonstrated, corresponding to absolute efficiency gains of 4.4% and 1.2% respectively compared to TiO2-based control cells. In addition, a steady-state efficiency of 16.6% for a semi-transparent cell is reported and it is used to achieve a four-terminal perovskite-silicon tandem cell with a steady-state efficiency of 24.5%.