Tandem Solar Cell

With more than 60 years research on photovoltaic (PV) solar cells since the first practical silicon-based device announced by Bell Laboratories in 1950s, solar cells are now publicly recognized as the most promising technology for obtaining the sustainable clean electrical energy. Nowadays, with single junction research cells efficiency approaching to its theoretical limit, developing multi-junction solar cells (Tandem solar cells) at low cost has become an inevitable path to overcome the intrinsic limiting factors in single junction cells, such as sub-bandgap photon loss and hot carrier thermalization loss. By splitting solar spectrum and utilising sub-cells to more efficiently convert the sub-spectrum bands to electricity, tandem solar cells over 30% efficiency at low fabrication cost is promising.

This goal is becoming more realistic with the emerging organic–inorganic lead halide perovskite materials discovered as thin film absorber to achieve over 22% efficiency. Perovskite material has high defect tolerance, long charge carrier diffusion lengths. More importantly, it offers bandgap tunability throughout a wide spectral range with high open circuit voltage (VOC)and low potential loss, which makes it perfect for tandem solar cell application. The versatile fabrication methods for perovskite thin films make it feasible to combine with other PV materials. Perovskite/Si, perovskite/perovskite or perovskite/OPV combination for tandem solar cells has been demonstrated as achievable structures for high efficiency solar cell. However, there are still huge research potentials to realize the high efficiency, stable, low cost large area tandem solar cells. With state-of-art thin film fabrication tools and characterization techniques in Monash University and our external research partners, we are developing and investigating large area perovskite thin film methods, new electron/hole transfer material for tandem cells, intermediate recombination layers and light management schemes for high efficiency multi-junction solar cells.

Graph reference:

Lal, N. N.; Dkhissi, Y.; Li, W.; Hou, Q.; Cheng, Y.-B.; Bach, U., Perovskite Tandem Solar Cells. Advanced Energy Materials 2017, 7, 1602761