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Journal article
Relating Carrier Dynamics and Photovoltaic Device Performance of Single-Crystalline Cu2ZnSnSe4
Physical review applied, v 11(3)
04 Mar 2019
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Understanding the relationship of photoexcited carrier lifetimes, mobilities, and recombination mechanisms to structural properties and processing of photovoltaic (PV) absorber materials is critical to the design of efficient solar cells. Carrier dynamics in PV absorbers have conventionally been characterized by time-resolved photoluminescence (TRPL), but TRPL may not be suitable or straightforward for all absorbers. Alternative noncontact methods can enable measurement of ultrafast carrier dynamics for a wider range of materials. Here, we demonstrate the complementary use of time-resolved terahertz spectroscopy (TRTS) and near-infrared transient reflectance (NIRTR) spectroscopy along with TRPL to elucidate photoexcited carrier dynamics in a high-quality copper-poor, zinc-rich kesterite Cu2ZnSnSe4 (CZTSe) single crystal. The single-crystalline nature of the sample eliminates complications arising from grain boundaries, secondary phases, and interfaces associated with thin-film growth. A single-crystal-based PV device exhibited an efficiency of 5.7% and an open circuit voltage (V-oc) of 400 mV, consistent with the quasi-Fermi-level splitting determined using absolute photoluminescence. NIRTR showed picosecond-scale cooling and relaxation of carriers into a distribution of band-tail states while TRTS revealed a characteristic time scale of 200-260 ps for recombination. Hall effect and TRTS measurements revealed electron and hole mobilities in the range of 50-100 cm(2)/V s. These dynamics result in a characteristic minority carrier diffusion length of less than 200 nm, leading to incomplete carrier collection, as confirmed by a strongly decreasing external quantum efficiency at long wavelengths. Our approach combining ultrafast spectroscopy and device measurements can lead to more detailed understanding of performance-limiting photophysical processes and can accelerate the development of more efficient PVs.
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Details
- Title
- Relating Carrier Dynamics and Photovoltaic Device Performance of Single-Crystalline Cu2ZnSnSe4
- Creators
- Siming Li - Drexel UniversityMichael A. Lloyd - University of DelawareHannes Hempel - Helmholtz-Zentrum Berlin für Materialien und EnergieCharles J. Hages - Helmholtz-Zentrum Berlin für Materialien und EnergieJose A. Marquez - Helmholtz-Zentrum Berlin für Materialien und EnergieThomas Unold - Helmholtz-Zentrum Berlin für Materialien und EnergieRainer Eichberger - Helmholtz-Zentrum Berlin für Materialien und EnergieBrian E. McCandless - University of DelawareJason B. Baxter - Drexel University
- Publication Details
- Physical review applied, v 11(3)
- Publisher
- Amer Physical Soc
- Number of pages
- 13
- Grant note
- H2020-NMBP-03-2016-720907 / H2020 programme under the project STARCELL DE-SC0012704 / U.S. DOE Office of Science Facility, at Brookhaven National Laboratory; United States Department of Energy (DOE) DMR-1507988; DMR-1508042 / National Science Foundation; National Science Foundation (NSF)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:000460675400002
- Scopus ID
- 2-s2.0-85062980712
- Other Identifier
- 991019168190304721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Physics, Applied