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 (V-oc) 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 10(4) 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 10(8) cm/s. By determining the locus and mechanisms of performance-limiting recombination, we can accelerate the development of thin-film PVs with higher V-oc and efficiency. While the method has been demonstrated here using CdTe, it is also applicable to perovskites, Cu(InGa)Se-2, Cu2ZnSn(S,Se)(4), and emerging technologies.
Distinguishing bulk and surface recombination in CdTe thin films and solar cells using time-resolved terahertz and photoluminescence spectroscopies
Creators
Mohammad M. Taheri - Drexel University
Triet M. Truong - Drexel University
Siming Li - National Renewable Energy Laboratory
William N. Shafarman - University of Delaware
Brian E. McCandless - University of Delaware
Jason B. Baxter - Drexel University
Publication Details
Journal of applied physics, v 130(16), p163104
Publisher
American Institute of Physics
Number of pages
10
Grant note
agency of the United States Government
DE-EE0008986 / U.S. Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy Technologies Office (SETO); United States Department of Energy (DOE)
Resource Type
Journal article
Language
English
Academic Unit
Materials Science and Engineering; Chemical and Biological Engineering
Web of Science ID
WOS:000714949800003
Scopus ID
2-s2.0-85118897725
Other Identifier
991019168391104721
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