High Efficiency Single Crystal CdTe Solar Cells: November 19, 2009 - January 31, 2011

Brian Keyes, Brian Keyes (NREL Technical Monitor)

Research output: NRELSubcontract Report


The goal of the program was to develop single crystal CdTe-based top cells grown on Si solar cells as a platform for the subsequent manufacture of high efficiency tandem cells for CPV applications. The keys to both the single junction and the tandem junction cell architectures are the ability to grow high quality single-crystal CdTe and CdZnTe layers on p-type Si substrates, to dope the CdTe andCdZnTe controllably, both n and p-type, and to make low resistance ohmic front and back contacts. EPIR demonstrated the consistent MBE growth of CdTe/Si and CdZnTe/Si having high crystalline quality despite very large lattice mismatches; epitaxial CdTe/Si and CdZnTe/Si consistently showed state-of-the-art electron mobilities and good hole mobilities; bulk minority carrier recombination lifetimesof unintentionally p-doped CdTe and CdZnTe grown by MBE on Si were demonstrated to be consistently of order 100 ns or longer; desired n- and p-doping levels were achieved; solar cell series specific resistances <10 ?-cm2 were achieved; A single-junction solar cell having a state-of-the-art value of Voc and a unverified 16.4% efficiency was fabricated from CdZnTe having a 1.80 eV bandgap, idealfor the top junction in a tandem cell with a Si bottom junction.
Original languageAmerican English
Number of pages47
StatePublished - 2011

Bibliographical note

Work performed by EPIR Technologies, Bolingbrook, Illinois

NREL Publication Number

  • NREL/SR-5200-51380


  • CdTe
  • epitaxial
  • photovoltaic


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