From Femtoseconds to Gigaseconds: Performance Degradation in Silicon Heterojunction Solar Cells

Davis G. Unruh, Chase M. Hansen, Reza Vatan Meidanshahi, Stephen Goodnick, Gergely T. Zimanyi

Research output: Chapter in Book/Report/Conference proceedingConference contribution


a-Si/c-Si heterojunction solar cells hold the efficiency world record around 27%, yet their market penetration is delayed. One concern is the presence of an amorphous Si layer that some suspect may speed up the degradation of their performance. To address this concern, we developed the SolDeg structural simulation platform that is capable of capturing extremely slow degradation processes in a-Si. SolDeg integrates molecular dynamics methods that optimize the Si structure with femtosecond time steps, with the nudged elastic band method that captures the defect generation on time scales extending to gigaseconds. In this paper we report SolDeg simulations for Si-only heterojunctions. The SolDeg platform enabled us to determine the defect generation rate to be in the 15-20%/year range, translating into a 1-1.5%/year Voc degradation rate. These results establish that SolDeg can be a uniquely useful platform to describe degradation processes with an eye on finding strategies to mitigate the performance degradation of these promising heterojunction cells.

Original languageEnglish (US)
Title of host publication2021 IEEE 48th Photovoltaic Specialists Conference, PVSC 2021
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages3
ISBN (Electronic)9781665419222
StatePublished - Jun 20 2021
Event48th IEEE Photovoltaic Specialists Conference, PVSC 2021 - Fort Lauderdale, United States
Duration: Jun 20 2021Jun 25 2021

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371


Conference48th IEEE Photovoltaic Specialists Conference, PVSC 2021
Country/TerritoryUnited States
CityFort Lauderdale

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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