Monolithic perovskite–silicon tandem solar cells with MoOx hole selective contact silicon bottom solar cells show a power conversion efficiency of 8%. A thin 15 nm-thick MoOx contact to n-type Si was used instead of a standard p+ emitter to collect holes and the SiOx/n+ poly-Si structure was deposited on the other side of the device for direct tunneling of electrons and this silicon bottom cell structure shows ~15% of power conversion efficiency. With this bottom carrier selective silicon cell, tin oxide, and subsequent perovskite structure were deposited to fabricate monolithic tandem solar cells. Monolithic tandem structure without ITO interlayer was also compared to confirm the role of MoOx in tandem cells and this tandem structure shows the power conversion efficiency of 3.3%. This research has confirmed that the MoOx layer simultaneously acts as a passivation layer and a hole collecting layer in this tandem structure.
Tunnel oxide passivated contact (TOPCon) solar cells are key emerging devices in the commercial silicon-solar-cell sector. It is essential to have a suitable bottom cell in perovskite/silicon tandem solar cells for commercial use, given that good candidates boost efficiency through increased voltage. This is due to low recombination loss through the use of polysilicon and tunneling oxides. Here, a thin amorphous silicon layer is proposed to reduce parasitic absorption in the near-infrared region (NIR) in TOPCon solar cells, when used as the bottom cell of a tandem solar-cell system. Lifetime measurements and optical microscopy (OM) revealed that modifying both the timing and temperature of the annealing step to crystalize amorphous silicon to polysilicon can improve solar cell performance. For tandem cell applications, absorption in the NIR was compared using a semitransparent perovskite cell as a filter. Taken together, we confirmed the positive results of thin poly-Si, and expect that this will improve the application of perovskite/silicon tandem solar cells.
Solution-processed
chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe)
solar modules are promising alternatives to conventional crystalline
silicon-based photovoltaic devices owing to their potential to lower
production costs and compatibility with large-area flexible substrates.
However, these modules typically exhibit a higher-than-expected cell-to-module
loss, which, in most cases, is attributed to the emergence of critical
shunt sites. In this study, we investigated the structural shunt defects
induced by delamination of the absorber in alcohol-based solution-processed
CIGSSe solar modules. Characterization with the use of lock-in thermography
indicated that most of the delamination-induced shunt defects emerged
locally near the patterned regions. Furthermore, secondary-ion mass
spectroscopy measurements showed that, rather than being uniformly
distributed, the alkali elements in the CIGSSe modules were concentrated
near the patterned regions. The results revealed that the uniformity
of this distribution is the key driving force behind absorber delamination.
Finally, we confirmed that delamination-induced shunt defects can
be alleviated by controlling the diffusion of alkali elements. Consequently,
the energy conversion efficiency of the alcohol-based solution-processed
CIGSSe solar modules was enhanced from 4.24 to 7.59% by introducing
a layer that acts as a thin-film diffusion barrier.
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