Ryan France is a senior scientist in the high-efficiency crystalline photovoltaics research group at NREL, where he investigates complex device structures and challenging III-V materials. He has specialized in the epitaxy of materials with dissimilar lattice-constants, which involves understanding influences on dislocation nucleation and glide. Research on compositionally-graded buffers for multijunction solar cells has involved investigating the interaction of dislocations with III-V atomic ordering, and the modification of optical properties of the buffer for increased transparency or selective reflection. He has designed inverted metamorphic multijunction devices with two to six junctions, several of which have led to record efficiencies. His current research interests include high-efficiency multijunction solar cells, lattice-mismatched and defective devices, heteroepitaxy and the integration of dissimilar materials, strained-layer epitaxy and superlattices, and the effects of strain and strain relaxation.

France earned his bachelor's degree in applied physics from Washington University in St. Louis, after which he researched single- and multi-crystalline silicon solar cells at the University of New South Wales. He then researched III-nitride LEDs at Boston University, where he earned a master's degree in electrical engineering, and earned a doctorate in materials science at the Colorado School of Mines while researching dislocation glide in III-V materials at NREL. He also participated in an NREL-Fraunhofer ISE research exchange, where he investigated III-V on Si growth and devices. 

Research Interests

Metamorphic epitaxy for multijunction solar cells

High-efficiency multijunction devices

Heteroepitaxy/integration of dissimilar materials

Strain, dislocation-material interaction, and lattice-mismatched devices

Education

Ph.D. Materials Science, Colorado School of Mines

M.S. Electrical Engineering, Boston University

B.S. Applied Physics, Washington University in St. Louis

Featured Work

Six-Junction III-V Solar Cells with 47.1% Conversion Efficiency under 143 Suns Concentration, Nature Energy (2020) 

Multijunction Solar Cells with Graded Buffer Bragg Reflectors, J. Photovolt. (2018)

Development of Lattice-Mismatched GaInAsP for Radiation Hardness, J. Photovolt. (2019)

Metamorphic Epitaxy for Multijunction Solar Cells, MRS Bulletin (2016)