Optimized Quantum Dot Superlattice Structures for Ultra-High Efficiency Photovoltaic Cells and Photodetectors

Higher efficiency solar cells are needed to reduce solar-array mass, volume, and cost. In this project we propose to develop: (i) a concept of the novel quantum dot superlattice (QDS) solar cells, which are estimated to be more efficient and radiation tolerant than conventional multi-junction solar cells, (ii) new computational tools for the quantum-dot nanostructure optimization for the specific applications. The developed models will be validated with experimental data from the Nano-Device Laboratory, UCR. It is anticipated that QD solar cells can achieve efficiencies of ~60% via optimization of the light absorption (“multicolor” effect via dot-size tuning), optical selection-rules relaxation and confinement-induced changes in the carrier transport (mini-band formation) and phonon dispersion. The user-friendly 3D modeling tools, to be developed at CFDRC, will be used for the QDS optimization for both photovoltaic and photodetector applications. Specific issues to be addressed include: (i) quantum dot ordering and size dispersion, (ii) enhanced photogenerated carrier separation and drift mobility; (iii) improved electric conductivity and increased collection efficiency. Phase I includes development of the numerical models for QDS and their experimental validation with prototype QDS. In Phase II we will use the developed modeling tools for the radiation-hardness optimization of QDS-based solar cells and detectors.