Why do we need tandem solar cells?

In summary, tandem solar cells are solar cells with multiple p-n junctions, while single junction solar cells have only one p-n junction. This is because tandem solar cells use two different wavelength absorbers, whereas single junction solar cells have multiple absorbers blended together. The reason for this is due to the relative LUMO energy levels between the high and low wavelength absorbers and the charge-transfer process involved in transferring electrons between them. In order to maximize energy efficiency, tandem solar cells require matched LUMO levels between donors and acceptors.
  • #1
derlin
2
0
I have a general question about tandem solar cells.

So tandem solar cells are solar cells with multiple p-n junctions in them.

However, why can't we have a single junction solar cell with multiple wavelength absorbers in them? That is to say, why do tandem solar cells need to be split into two separate subcells? To be clear, I'm talking about this from the viewpoint of organic solar cells. So I'm imagining a bulk heterojunction solar cell, where the absorbing section is a blend of two different wavelength absorbers.

I have a suspicion that it has to do with the relative LUMO energy levels between the high and low wavelength absorbers and the charge-transfer process that transfers an electron from the donor's LUMO to the acceptor's LUMO. But I can't quite reason it out to my satisfaction.

Any ideas?
 
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  • #2
I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
 
  • #3
Ah its ok. I was just curious, so I didn't need a super concrete answer. I think my suspicion was correct in that if you had multiple donors, you would need multiple acceptors with matched LUMO levels to undergo the charge transfer process so that you wouldn't lose all of the energy from your high-energy absorbing donor molecule.
 

1. What are tandem solar cells and how do they work?

Tandem solar cells are a type of solar cell that consists of two or more layers of photovoltaic materials stacked together. Each layer is designed to absorb a specific range of wavelengths of light, allowing for a more efficient use of the solar spectrum. The top layer absorbs the high-energy, short-wavelength light, while the bottom layer absorbs the low-energy, long-wavelength light. This combination allows for a higher conversion efficiency than traditional single-layer solar cells.

2. What advantages do tandem solar cells have over traditional single-layer solar cells?

Tandem solar cells have several advantages over traditional single-layer solar cells. One major advantage is their higher efficiency, as they are able to absorb a wider range of wavelengths of light. This means they can generate more electricity from the same amount of sunlight. Additionally, tandem solar cells can be made with a wider variety of materials, allowing for more flexibility in their design and potential for cost reduction.

3. How are tandem solar cells made?

Tandem solar cells are typically made using a technique called layer-by-layer deposition. This involves depositing thin layers of different photovoltaic materials one on top of the other, using techniques such as chemical vapor deposition or sputtering. The materials used in tandem solar cells are carefully chosen to optimize the absorption of different wavelengths of light and to create efficient energy transfer between layers.

4. What applications are tandem solar cells best suited for?

Tandem solar cells are best suited for applications where high efficiency and energy density are important, such as in space satellites, where space and weight are limited. They are also well-suited for building-integrated photovoltaics, where space for solar panels is limited. Tandem solar cells are also being researched for use in large-scale solar power plants, where their higher efficiency can lead to a significant increase in power output.

5. What are the current challenges in the development of tandem solar cells?

One of the main challenges in the development of tandem solar cells is finding the right combination of materials that can efficiently work together to absorb and convert sunlight into electricity. This involves extensive research and testing to find the most cost-effective and stable materials. Another challenge is scaling up production of tandem solar cells to make them more commercially viable. Additionally, the cost of materials and production processes must be carefully considered to make tandem solar cells competitive with traditional single-layer solar cells.

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