Charge Carrier Lifetime Determination in Graded Absorber Solar Cells Using Time-Resolved Photoluminescence Simulations and Measurements

Alexandra M. Bothwell, Carey L. Reich, Adam H. Danielson, Arthur Onno, Zachary C. Holman, Walajabad S. Sampath, Darius Kuciauskas

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Thin-film photovoltaic device efficiencies are limited by carrier recombination, thus understanding recombination mechanisms is critical for performance improvements. Bulk minority carrier lifetime (τ bulk) is a critical parameter for solar cells but is difficult to determine in P–N junction devices, especially for high doping. As doping ≥1016 cm−3 is required for efficient drift-charge-carrier-collection devices, a method for τ bulk determination in doped P–N junction devices is necessary. This work utilizes time-resolved photoluminescence (TRPL) simulations to quantify bulk and interface recombination properties in highly doped, graded absorber CdSeTe structures. The two methods developed here for τ bulk determination include utilization of an instantaneous lifetime representation to guide TRPL fitting and direct comparison between measured and simulated decays. Simulations verified that both methods are valid for state-of-the-art device architectures which include graded bandgap absorbers, graded doping, and graded lifetimes. Shifts in the dominant recombination mechanism are identified for sufficiently long τ bulk, where front and back interface quality plays a more prominent role. Evaluation of surface recombination velocities and conduction band offset illustrate electro-optical advantages of a positive conduction band offset and highlight the necessity of improved interfaces as bulk quality in photovoltaic devices improves.

Original languageEnglish (US)
Article number2201029
JournalSolar RRL
Issue number9
StatePublished - May 2023


  • carrier lifetime
  • doping
  • interfaces
  • solar cells
  • time-resolved photoluminescence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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