Solar cell spectrum mismatch

Why is spectral mismatch limiting solar cell efficiencies?

The spectral mismatch between solar cells and incident radiation is a fundamental factor limiting their efficiencies. There exist materials and luminescent processes which can modify the incident sunlight’s properties to better suit the cell’s optimal absorption regions.

What is spectral mismatch?

Collectively this problem is referred to as the spectral mismatch between the incident solar spectrum and absorption profile of the cell; it stems from a defined energy called the band gap energy, E G, which is present in all materials that can harness solar power.

Why is spectral mismatch a detriment to a cell's efficiency?

Furthermore photons of E > E G contribute to thermalization losses. This is because when absorbed they possess excess energy than required to generate photocurrent, so electrons are promoted into the conduction band with additional kinetic energy which is wasted as heat. Therefore the spectral mismatch is the key detriment to a cell’s efficiency.

What happens if a solar cell reaches 210 mA/cm2?

At a level of 210 suns the short-circuit current increased by 13.1 mA/cm 2, corresponding to a relative efficiency increase of 0.19% [ 115 ]. A further complication arises because the optimal solar concentration for the cell will differ to the ideal conditions for the spectral conversion layer.

What percentage of solar spectrum does a silicon cell absorb?

The percentages of the solar spectrum represented as the energy losses that occur in a silicon cell. The spectral mismatch is responsible for approximately 50% of these through non-absorption and thermalization. The structure of an epitaxial triple junction cell and regions of the spectrum it can absorb are shown. Figures modified from Refs.

Why is spectral conversion a complication of integrated optics-solar PV systems?

A further complication arises because the optimal solar concentration for the cell will differ to the ideal conditions for the spectral conversion layer. Some groups have investigated this imbalance and constructed integrated optics-solar PV systems to compensate for the difference in concentration levels.