Distinguishing Bulk and Surface Recombination in CdTe Thin Films and Solar Cells Using Time-Resolved Terahertz and Photoluminescence Spectroscopies: Article No. 163104

Mohammad Taheri, Triet Truong, Siming Li, William Shafarman, Brian McCandless, Jason Baxter

Research output: Contribution to journalArticlepeer-review

5 Scopus Citations

Abstract

Understanding the nature of recombination and its dependence on defects and interfaces is essential for engineering materials and contacts for a higher open-circuit voltage (Voc) and power conversion efficiency in photovoltaic (PV) devices. Time-resolved photoluminescence (TRPL) has conventionally been used to evaluate recombination, but carrier redistribution often dominates the response at short times. Here, we report on the quantification of carrier dynamics and recombination mechanisms by complementary use of both time-resolved terahertz spectroscopy and TRPL combined with numerical modeling of the continuity equations and Poisson's equation. We have demonstrated this approach using CdTe thin films. A thin-film stack with CdTe fabricated by vapor transport deposition and treated with CdCl2 exhibited a bulk lifetime of 1.7 +/- 0.1 ns, a negligible CdTe/CdS interface recombination velocity, and a back surface recombination velocity of 6.3 +/- 1.3 x 104 cm/s. In contrast, a film stack without CdCl2 treatment had a bulk lifetime of only 68 +/- 12 ps and a higher interface recombination velocity of 4 +/- 2 x 108 cm/s. By determining the locus and mechanisms of performance-limiting recombination, we can accelerate the development of thin-film PVs with higher Voc and efficiency. While the method has been demonstrated here using CdTe, it is also applicable to perovskites, Cu(InGa)Se2, Cu2ZnSn(S,Se)4, and emerging technologies.
Original languageAmerican English
Number of pages10
JournalJournal of Applied Physics
Volume130
Issue number16
DOIs
StatePublished - 2021

NREL Publication Number

  • NREL/JA-5900-81617

Keywords

  • photovoltaics
  • semiconductors
  • solar cells
  • terahertz spectroscopy
  • thin film devices
  • time-resolved photoluminescence

Fingerprint

Dive into the research topics of 'Distinguishing Bulk and Surface Recombination in CdTe Thin Films and Solar Cells Using Time-Resolved Terahertz and Photoluminescence Spectroscopies: Article No. 163104'. Together they form a unique fingerprint.

Cite this