This project aimed to overcome the limitations of normal solar cells by developing a solar cell coating that can harvest sub-threshold light.
Most commercial solar cells are limited to absorbing particles of light above a certain threshold energy. This causes their energy conversion efficiency (the amount of energy that can be converted from light) to be limited to about 33% under standard illumination.
This project overcame the limitations of normal solar cells, which are incapable of using sunlight beyond a certain wavelength, by developing a solar cell coating that could harvest sub-threshold light. The coating captures this light and converts it to a useable wavelength to boost the cell’s efficiency.
The process that harvests the part of the solar spectrum currently unused by solar cells is known as upconversion.
The upconversion process harvests low energy photons and ‘glues’ them together to make higher energy photons that can then be reflected back into the cell for harvesting.
By designing the molecules to absorb and emit the wavelength of interest, upconverters can be tailor-made to fit many applications.
This technology will lay the foundations for improving the efficiency of any single threshold solar cell, bringing down the cost of solar energy.