Overcoming theoretical limits on solar cell capacity
- March 14, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Overcoming theoretical limits on solar cell capacity
Subject: Science and tech
Section: Msc
Photovoltaics and solar cells:
- Photovoltaics is a study focusing on the conversion of light energy into electrical energy.
- Solar cells, which are key devices in photovoltaics, harness the energy from the Sun, Earth’s primary light and energy source.
- Solar cells are comprised of semiconducting materials, such as doped silicon, that facilitate this energy conversion.
How Solar Cells Work:
- Sunlight interacting with semiconductor sex cites electrons from a lower-energy valence band to a higher-energy conduction band, leaving behind a “hole” in the valence band.
- A hole represents a vacant site with a positive charge due to the absence of an electron.
- The transition of electrons and the creation of holes generate electron-hole pairs, essential for creating photocurrent in semiconductors.
The Shockley-Queisser Limit:
- It is a theoretical concept that defines the maximum efficiency potential of a solar cell to produce electricity.
- Named after Physicists William Shockley (U.S.) and Hans-Joachim Queisser (Germany).
- Factors such as transparency loss (~25%) and thermalisation (~30%) limit the maximum efficiency of solar cells.
- Modern solar cells convert only about a third of the incident solar energy into electrical energy.
Challenges and Innovations:
- Semiconductors struggle to utilize photons with either insufficient energy to overcome the band gap or those with excess energy that merely heats the device.
- Efforts to surpass the Shockley-Queisser limit include carrier multiplication (allowing a photon to create multiple electron-hole pairs) and hot carrier extraction (capturing high-energy photons before they convert to heat).
- South Korean physicist Young Hee Lee highlights these methods as promising pathways to enhance solar cell efficiency.
Source: TH