Solar photovoltaic power generators, also known as solar cells, convert sunlight directly into electricity. The installation of solar cells is growing rapidly (30% per year) and solar cells are projected to become an increasingly significant source of energy for our society. Because of the vast quantity of energy available from the sun, solar energy has the potential to scale to meet our entire energy demands.
Fig. 5. (above). Solar cells have been growing at 30% per year. But solar will require many more years of growth at this rapid rate to be a significant source of energy.
Organic Photovoltaics and Solar Concentrators
We are developing organic solar cells and luminescent solar concentrators. The aim of these projects is to reduce the cost of solar cells. Organic solar cells aim to employ molecules in place of the semiconductors within conventional solar cells. The molecular materials within organic solar cells are plentiful and compatible with low cost manufacturing. Luminescent solar concentrators use organic dye molecules to absorb solar radiation and then re-radiate the energy within a waveguide which concentrates the light on conventional solar cells. By concentrating sunlight, this technology can boost the power output of a conventional solar cell by up to a factor of 30. See more about this work on photovoltaics at: http://softsemi.mit.edu/Research
Fig. 6. The operating principle of a luminescent solar concentrator is demonstrated by this dye-doped plastic rod. Light absorbed by the rod is re-emitted by the dye and guided to the end of the rod where it can be collected by a solar cell.
Solution processable colloidal quantum dot systems exhibit many of the special optical and electronic properties associated with much more expensive epitaxially grown materials. Their tunable band gap and higher absorption relative to the bulk make quantum dots particularly attractive as photogeneration materials. We employ a microcontact printing method to deposit a thin quantum dot film onto a wide band gap semiconductor, thus producing an inorganic/organic heterojunction which serves to enhance charge separation in the device. The present focus is on improving the device performance in the 1µm to 2µm wavelength region by using
different quantum dot film chemistries.