Roles of Bandgrading, Lifetime, Band Alignment, and Carrier Concentration in High-Efficiency CdSeTe Solar Cells: Article No. 053102

Xin Zheng, Eric Colegrove, Joel Duenow, John Moseley, Wyatt Metzger

Research output: Contribution to journalArticlepeer-review

22 Scopus Citations

Abstract

CdSeTe alloying has significantly increased the efficiency of CdTe-based solar technology. Here, computational modeling compares how different CdSeTe bandgrading, carrier lifetimes, band alignment, and carrier concentrations contribute to transport, recombination, and performance. We find that the gain in photocurrent caused by bandgap narrowing alone is insufficient to describe experimental efficiency gains. Performance can be increased by adjusting CdSeTe compositions and bandgrading depths. However, these performance gains are small relative to the contributions of enhanced lifetime by Se alloying, which can explain record cell efficiency gains with minimal open-circuit voltage loss despite significant bandgap narrowing. Similarly, CdSeTe band alignment shifts can significantly increase performance if front interface recombination is prevalent. For a wide range of CdSeTe grading profiles, the hole density is a critical component to achieve efficiencies exceeding 25%.
Original languageAmerican English
Number of pages7
JournalJournal of Applied Physics
Volume128
Issue number5
DOIs
StatePublished - 2020

NREL Publication Number

  • NREL/JA-5K00-76812

Keywords

  • electrical properties and parameters
  • heterostructures
  • numerical methods
  • selenium
  • thin films
  • transport properties

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