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. This project proposes: (i) Reliable, validated models for simulation, analysis, and design of Quantum Dot Superlattice (QDS) based nano-materials for high-efficiency, radiation-hardened photovoltaic cells and photodetectors; (ii) Verify and demonstrate models by experiments; (iii) Implement novel models in CFDRC's three-dimensional (3D) device simulator, NanoTCAD. The developed models will be validated with experiments of participants: University of California Riverside Nano-Device Laboratory, Rochester Institute of Technology, and University of New Mexico. Novel models and simulation tools open a way to high-efficiency rad-hard solar cells and photodetectors. It is anticipated that QDS solar cells can achieve efficiencies of 60% via optimization of the light absorption ("multicolor" cell), optical selection-rule relaxation, confinement-enhanced carrier transport (mini-band formation), and phonon dispersion. The proposed tools can be used for the QDS optimization for photovoltaic, photodetector, and laser applications. Specific issues 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 demonstrated prototype physics-based models for QDS and their preliminary validation. In Phase II, we will complete the development of physics-based models, implement them in CFDRC's NanoTCAD, and demonstrate for analysis and development of more efficient, rad-hard photovoltaic nano-technology for space solar cells and improved photodetectors.