Semiconductor heterostructures and optimization of light-trapping structures for efficientthin-film solar cells

Abstract

Sub-wavelength photonic structures and nanoscale materials have the potential to greatlyimprove the efficiencies of solar cells by enabling maximum absorption of sunlight.Semiconductor heterostructures provide versatile opportunities for improving absorption ofinfrared radiation in photovoltaic devices, which accounts for half of the power in the solarspectrum. These ideas can be combined in quantum-well solar cells and related structuresin which sub-wavelength metal and dielectric scattering elements are integrated for lighttrapping. Measurements and simulations of GaAs solar cells with less than one micron ofactive material demonstrate the benefits of incorporating In(Ga)As quantum-wellsand quantum-dots to improve their performance. Simulations that incorporate arealistic model of absorption in quantum-wells show that the use of broadbandphotonic structures with such devices can substantially improve the benefit ofincorporating heterostructures, enabling meaningful improvements in their performance.