Inserting a Low-Refractive-Index Dielectric Rear Reflector into PERC Cells: Challenges and Opportunities

Michael Deceglie, Timothy Silverman, Jonathan Bryan, Lejo Koduvelikulathu, Zih-Wei Peng, Joe Carpenter III, Zachary Holman

Research output: Contribution to conferencePaperpeer-review

3 Scopus Citations


One of the simplest and most effective ways to reduce the operating temperature of photovoltaic systems in the field is to reflect unusable, "sub-bandgap" light with energies below the cell absorber's bandgap energy. In this work, low-refractive index SiO2 nanoparticle films inserted between c-Si wafers and metal electrodes significantly increase the reflectance of sub-bandgap light in fabricated test structures. These films are then integrated into the standard PERC fabrication sequence, revealing that the reflection benefits remains after some processing steps but are lost in certain conditions. The SiO2 nanoparticle films are easily ablated during laser contact opening, but are undesirably etched during post-laser cleaning. After Al metallization, the fully fabricated devices show enhanced sub-bandgap reflection when annealed at moderate temperatures, but energy-dispersive x-ray spectroscopy shows that high-temperature firing causes unwanted Al penetration into the SiO2 nanoparticle film, compromising reflection.

Original languageAmerican English
Number of pages5
StatePublished - Jun 2019
Event46th IEEE Photovoltaic Specialists Conference, PVSC 2019 - Chicago, United States
Duration: 16 Jun 201921 Jun 2019


Conference46th IEEE Photovoltaic Specialists Conference, PVSC 2019
Country/TerritoryUnited States

Bibliographical note

See NREL/CP-5K00-75157 for preprint

NREL Publication Number

  • NREL/CP-5K00-76282


  • crystalline silicon
  • energy yield
  • module temperature
  • optics
  • PERC solar cell
  • photovoltaic cells
  • photovoltaic systems
  • thermal management


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