High performance low-bandgap (0.8 eV) single junction GaInNAsSb solar cells incorporating Au-based back surface reflectors

Research output: Contribution to journalArticleScientificpeer-review

16 Downloads (Pure)

Abstract

Low-bandgap GaInNAsSb single junction solar cells incorporating a planar Au back surface reflector for enhancing the photocurrent generation are reported. In particular, a 700 nm thick GaInNAsSb junction with a bandgap of 0.78 eV (corresponding to 6.2% N) incorporating the back reflector exhibited a short-circuit current density of 15.2 mA/cm2 for AM1.5D (1000 W/m2) illumination, when placed underneath a GaAs-filter mimicking the operation of a multijunction architecture. The corresponding external quantum efficiency represents the highest external quantum efficiency reported so far for dilute nitride solar cells with bandgaps below 0.8 eV. Electrical simulations reveal that the relatively high value of the quantum efficiency is attributed to a low p-type carrier concentration and partially to the varying doping level in the GaInNAsSb region. Moreover, the absorption coefficients for low-bandgap GaInNAsSb materials are estimated and used in a comprehensive optical analysis to understand the photon harvesting performance of the solar cells with reflector. The analysis reveals incomplete absorption in the GaInNAsSb layers for the double-pass configuration enabled by the planar back reflector pointing to the need for deploying more advanced structured reflectors. However, the structures exhibited high collection efficiencies laying the foundation for further improvements of the quantum efficiency values. Moreover, the low-bandgap dilute nitride solar cells show potential to meet the current-matching requirements in next-generation multijunction devices with five or more junctions, thus being a prospective alternative for replacing Ge as the bottom junction.
Original languageEnglish
Number of pages10
JournalSolar Energy Materials & Solar Cells
Volume234
Early online date7 Oct 2021
DOIs
Publication statusPublished - Jan 2022
Publication typeA1 Journal article-refereed

Keywords

  • Dilute nitrides
  • Back surface reflector
  • Molecular beam epitaxy
  • GaInNAsSb
  • Multijunction solar cells

Publication forum classification

  • Publication forum level 2

Fingerprint

Dive into the research topics of 'High performance low-bandgap (0.8 eV) single junction GaInNAsSb solar cells incorporating Au-based back surface reflectors'. Together they form a unique fingerprint.

Cite this