Two-terminal metal-inter-connected multijunction III-V solar cells

• Published in: Progress in photovoltaics Vol. 23; no. 5; pp. 593 - 599
• Main Authors: Lin, Chieh-Ting, McMahon, William E., Ward, James S., Geisz, John F., Wanlass, Mark W., Carapella, Jeffrey J., Olavarria, Waldo, Perl, Emmett E., Young, Michelle, Steiner, Myles A., France, Ryan M., Kibbler, Alan E., Duda, Anna, Moriarty, Tom E., Friedman, Daniel J., Bowers, John E.
• Format: Journal Article
• Language: English
• Published: Bognor Regis Blackwell Publishing Ltd 01.05.2015; Wiley Subscription Services, Inc
• Subjects: Bonding; concentrator photovoltaic; device bonding; Devices; Dielectrics; Dissimilar materials; Gallium arsenide; Gallium arsenides; III-V semiconductor; multijunction; Photovoltaic cells; Solar cells; thermal compression bond; Topology
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.2468

A novel bonding approach with an interface consisting of a metal and dielectric is developed, and a “pillar‐array” metal topology is proposed for minimal optical and electrical loss at the interface. This enables a fully lattice‐matched two‐terminal, four‐junction device that consists of an inverted top two‐junction (2J) cell with 1.85 eV GaInP/1.42 eV GaAs, and an upright lower 2J cell with ~1 eV GaInAsP/0.74 eV GaInAs aimed for concentrator applications. The fabrication process and simulation of the metal topology are discussed along with the results of GaAs/GaInAs 2J and (GaInP + GaAs)/GaInAs three‐junction bonded cells. Bonding‐related issues are also addressed along with optical coupling across the bonding interface. Copyright © 2014 John Wiley & Sons, Ltd. A novel bonding method for multijunction photovoltaic devices that allows integration of dissimilar material is presented and demonstrated. The bonding interface utilizes a metal and dielectric with “pillar‐array” topology to minimize optical and electrical loss. Process‐related damage were addressed along with results of various bonded devices including a bonded triple‐junction device with Voc = 2.70 V, Jsc = 12.66 mA/cm2, fill factor = 83.0%, and efficiency = 28.39% under the 1‐sun American Society for Testing and Materials (ASTM) G173 direct spectrum.