Improved performance of In„Ga…As/GaAs quantum dot solar cells via light scattering by nanoparticles

InAs quantum dots have been used to extend the absorption edge of InGaAs/GaAs quantum well solar cells from 940 to 1100 nm. In order to improve absorption of infrared radiation by the thin 300 nm active layer, we exploit its high refractive index, which acts as a waveguide for certain frequencies of light. Surface-deposited nanoparticles scatter incident radiation into waveguide modes of the devices, yielding improved infrared photocurrent generation of at least 10 % at all wavelengths between 700 and 1100 nm, short-circuit current density increases of up to 16%, and corresponding gains in power conversion efficiency. © 2009 American Institute of Physics. doi:10.1063/1.3213366 Solar cells based on low-dimensional semiconductor structures are currently of outstanding interest for develop-ment of high-efficiency photovoltaics.1–4 In particular, quan-tum well solar cells QWSCs and quantum dot solar cells QDSCs have been proposed as a means of exceeding the Shockley–Queisser limit of 31 % power conversion effi-ciency for homojunction devices.1,2,5 Incorporation of QD