Journal article
Effects of cation composition on carrier dynamics and photovoltaic performance in Cu2ZnSnSe4 monocrystal solar cells
Solar energy materials and solar cells, v 205, p110255
01 Feb 2020
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Understanding the relationship of doping density, carrier lifetime, and interface recombination to device performance is critical to designing solar cells with high power conversion efficiency (PCE). In turn, it is necessary to understand how bulk material composition determines doping density and carrier lifetime. The most efficient kesterite Cu2ZnSn(S,Se)(4) (CZTSSe) thin film solar cells have had Cu-poor, Zn-rich compositions, while more stoichiometric compositions have lower PCEs. However, thin films are grown under highly non-equilibrium conditions, complicating fundamental studies. Here we report on a set of CZTSe monocrystals with varied cation stoichiometry, enabling correlation of bulk composition to material and device properties without the complication of grain boundaries or secondary phases. Copper-poor, zinc-rich compositions (Cu/(Zn + Sn) =0.77-0.90 and Zn/Sn = 1.17-1.25) yield bulk carrier lifetimes longer than 200 ps and PCE >5%. In contrast, near-stoichiometric compositions, with Cu/(Zn + Sn) > 0.90 and Zn/Sn < 1.15, have carrier lifetimes shorter than 20 ps and PCE <2%. CZTSe/CdS interface recombination velocity has a similar value to the CZTSe surface recombination velocity, with values of 10(4)-10(5) cm/s determined by time-resolved terahertz spectroscopy and transport-recombination modeling. Device modeling reveals the dependence of open circuit voltage (V-OC) on doping density, carrier lifetime and interface recombination. For a crystal with low doping density of 10(15) cm(-3), the maximum V-OC is limited by the bulk lifetime. Higher V-OC can be attained with higher doping density, but interface recombination becomes more significant with increased lifetime and doping density. These simulations indicate limitations and potential pathways to high performance.
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Details
- Title
- Effects of cation composition on carrier dynamics and photovoltaic performance in Cu2ZnSnSe4 monocrystal solar cells
- Creators
- Siming Li - Drexel UniversityMichael A. Lloyd - University of DelawareBrian E. McCandless - University of DelawareJason B. Baxter - Drexel University
- Publication Details
- Solar energy materials and solar cells, v 205, p110255
- Publisher
- Elsevier
- Number of pages
- 7
- Grant note
- 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:000504780000018
- Scopus ID
- 2-s2.0-85074876951
- Other Identifier
- 991019168323004721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Energy & Fuels
- Materials Science, Multidisciplinary
- Physics, Applied