Nanostructure engineering of infrared-bandgap nanomaterials based solar cells

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Multi-junction photovoltaics, particularly tandem and triple-junction solar cells, are efficient approaches to convert solar energy into electricity, since their constitute semiconductor materials have bandgaps from visible down to infrared (IR) regions and are capable of collecting full-spectrum of solar energy. Solution-processed colloidal quantum dots (CQDs), nanoparticles whose diameter determines which of the sun's broad spectrum of colours these materials absorb, are candidates for light-absorbing layers in multi-junction photovoltaics. We will develop high-efficiency, low-cost tandem and trip-junction solar cells with solution-processed PbS CQDs as IR harvesters. In the proposed research program, we will develop high-efficiency infrared-bandgap CQD solar cells. Specifically, we are targeting a device having external quantum efficiency of 80% in infrared region by trapping light in sub-micron thick CQD films through nanostructure engineering. We will further develop a physics model to evaluate the performance enhancement in CQD solar cells through modeling and experiment, and extend our research on nanostructured photovoltaics beyond CQD solar cells to achieve light management of reemitted light for breaking the Shockley-Queisser limit. The proposed works provide engineering solutions to achieve high infrared photon-to-electricity conversion by infrared-bandgap nanomaterials, which will enable the multi-junction solar cells for full solar spectrum harvesting. Integrated with smart-grid technology to manage electricity supplies, PbS CQDs and visible-bandgap materials will enable large-scale adoption of low-cost, high-efficiency multi-junction solar cells as energy source, which is critical to Canada and the world's future.