Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors

Research output: Contribution to journalArticle

Abstract

A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.

Details

Authors
Organisations
External organisations
  • Halmstad University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Nano Technology
  • Energy Systems

Keywords

  • distributed Bragg reflectors (DBRs), light trapping, nanowires, photovoltaics
Original languageEnglish
Pages (from-to)819-825
JournalNanophotonics
Volume7
Issue number5
Early online date2018 Mar 21
Publication statusPublished - 2018 May 24
Publication categoryResearch
Peer-reviewedYes