Design of Semiconductor-Based Back Reflectors for High Voc Monolithic Multijunction Solar Cells: Preprint

Conference · Fri Jun 01 00:00:00 EDT 2012

OSTI ID:1046260

Garcia, Ivan; Geisz, John; Steiner, Myles; Olson, Jerry; Friedman, Daniel; Kurtz, Sarah

State-of-the-art multijunction cell designs have the potential for significant improvement before going to higher number of junctions. For example, the Voc can be substantially increased if the photon recycling taking place in the junctions is enhanced. This has already been demonstrated (by Alta Devices) for a GaAs single-junction cell. For this, the loss of re-emitted photons by absorption inthe underlying layers or substrate must be minimized. Selective back surface reflectors are needed for this purpose. In this work, different architectures of semiconductor distributed Bragg reflectors (DBR) are assessed as the appropriate choice for application in monolithic multijunction solar cells. Since the photon re-emission in the photon recycling process is spatially isotropic, the effectof the incident angle on the reflectance spectrum is of central importance. In addition, the DBR structure must be designed taking into account its integration into the monolithic multijunction solar cells, concerning series resistance, growth economics, and other issues. We analyze the tradeoffs in DBR design complexity with all these requirements to determine if such a reflector is suitable toimprove multijunction solar cells.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1046260
• Report Number(s): NREL/CP-5200-54223
• Conference Information: Presented at the 2012 IEEE Photovoltaic Specialists Conference, 3-8 June 2012, Austin, Texas
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
BRAGG REFLECTION
DESIGN
distributed Bragg reflector
high VOC
LAYERS
MEETINGS
multijunction solar cells
photon recycling
PHOTONS
SEMICONDUCTOR JUNCTIONS
SOLAR CELLS
SOLAR REFLECTORS
SPECTRAL REFLECTANCE
SUBSTRATES
SURFACES