• Universitat de València
• Commissariat a l’energie atomique et aux energies alternatives

• Delfina Muñoz
• Perrine Carroy

The dominant technology on the market for photovoltaic cells (PV) are silicon-based PV cells, which are reaching their efficiency limit. To further increase the efficiency of Si solar cell a second semiconductor integrated into a second sub-cell is needed. This second sub-cell can either be a semi-transparent cell placed in front of a typical Si-cell or can be integrated onto the unfinished Si cell. The first approach is referred to as a 4-terminal (4T) tandem cell, as it contains 4 electrodes, 2 for each sub-cell. The second approach is referred to as 2-terminal (2T) or mono-lithic tandem cells. 2T tandem cells have benefits over 4T cells as production costs are less. Perovskite based solar cells have been identified as ideally suited to be used as the front cell in such a 2T tandem cell. However, state of the art 2T perovskite-silicon tandem solar cells may suffer from low yield, low open-circuit voltage, low short-circuit current, low efficiency, short lifetime and/ or low fill factor. Thus, 2T- perovskite-silicon tandem solar cell which overcomes drawbacks of the state of the art is needed.

Researchers from the Universitat de València and Commissariat a l’energie atomique et aux energies alternatives have developed new perovskite-silicon tandem cells with indium free charge recombination layer.

Currently, charge recombination layers in perovskite-silicon tandem are based on conductingmetal oxides. Most of them contain indium which is a scarce material. This invention can simplify the fabrication of perovskite/tandem solar cells and allows a much more conformal growth of the perovskite top cell on textured silicon substrate that makes it compatible with the industrial silicon-based solar cells. This would make easier the upgrade of Si-based PV manufacturing lines to perovskite/Si tandem lines with minimal or no change in the bottom cell process.

The invention provides a 2T- perovskite-silicon tandem solar cell which overcomes drawbacks of the prior art. It demonstrates the benefits of using an all-molecular semiconductor charge recombination junction that is an indium free and can be employed with simple thermal sublimation sources.

The invention is applicable in photovoltaics devices and also in other semiconductor devices such as light emitting diodes.

The invention has the following advantages:

• Production of indium free perovskite-silicon tandem cells.
• Production of perovskite/tandem solar cells is possible for industrial lines.
• High yield and performance tandem cells.

• Patent granted