Device comparison of champion nanocrystal-ink based CZTSSe and CIGSSe solar cells: Capacitance spectroscopy

Hages, Charles J.; Carter, Nathaniel J.; Moore, James E.; McLeod, Steven M.; Miskin, Caleb K.; Joglekar, Chinmay; Lundstrom, Mark

doi:10.1109/pvsc.2013.6744856

Cited by 11 publications

(5 citation statements)

References 21 publications

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“…The ts-TRPL data have been uniformly scaled in Figure 4b to the measured initial carrier injection Δn t=0 , which allows for determining the free carrier density p 0 ≈ 1.8 × 10 16 cm −3 for CZTSSe. This value is in good agreement with the free carrier density measured by capacitance-voltage profiling on devices measured here (see the Supporting Information) and on equivalently processed CZTSSe devices, [20,43] illustrating the benefit of intensity-dependent TRPL in extracting this parameter for absorbers without the need for device fabrication.…”

Section: Intensity-dependent and Spectrally Resolved Trplsupporting

confidence: 86%

Identifying the Real Minority Carrier Lifetime in Nonideal Semiconductors: A Case Study of Kesterite Materials

Hages

Redinger

Levcenko

et al. 2017

Advanced Energy Materials

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Time‐resolved photoluminescence (TRPL) is a powerful characterization technique to study carrier dynamics and quantify absorber quality in semiconductors. The minority carrier lifetime, which is critically important for high‐performance solar cells, is often derived from TRPL analysis. However, here it is shown that various nonideal absorber properties can dominate the TRPL signal making reliable extraction of the minority carrier lifetime not possible. Through high‐resolution intensity‐, temperature‐, voltage‐dependent, and spectrally resolved TRPL measurements on absorbers and devices it is shown that photoluminescence (PL) decay times for kesterite materials are dominated by minority carrier detrapping. Therefore, PL decay times do not correspond to the minority carrier lifetime for these materials. The lifetimes measured here are on the order of hundreds of picoseconds in contrast to the nanosecond lifetimes suggested by the decay curves. These results are supported with additional measurements, device simulation, and comparison with recombination limited PL decays measured on Cu(In,Ga)Se2. The kesterite material system is used as a case study to demonstrate the general analysis of TRPL data in the limit of various measurement conditions and nonideal absorber properties. The data indicate that the current bottleneck for kesterite solar cells is the minority carrier lifetime.

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Section: Intensity-dependent and Spectrally Resolved Trplsupporting

confidence: 86%

Identifying the Real Minority Carrier Lifetime in Nonideal Semiconductors: A Case Study of Kesterite Materials

Hages

Redinger

Levcenko

et al. 2017

Advanced Energy Materials

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119

150

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“…Using admittance spectroscopy, we have shown that this deep defect distribution is detrimental for the V oc . 6 Such a signature of the deep defect distribution observed by admittance spectroscopy is not only measured for devices from University of Luxembourg but also in various other literature reports, 7,8 including a 10.1% efficient CZTSSe device, 9 and therefore might be of interest for further studies.…”

Section: Introductionmentioning

confidence: 71%

Impact of annealing on electrical properties of Cu2ZnSnSe4 absorber layers

Weiss

Redinger

Rey

et al. 2016

Journal of Applied Physics

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Reported growth processes for kesterite absorber layers generally rely on a sequential process including a final high temperature annealing step. However, the impact and details for this annealing process vary among literature reports and little is known on its impact on electrical properties of the absorber. We used kesterite absorber layers prepared by a high temperature coevaporation process to explicitly study the impact of two different annealing processes. From electrical characterization it is found that the annealing process incorporates a detrimental deep defect distribution. On the other hand, the doping density could be reduced leading to a better collection and a higher short circuit current density. The activation energy of the doping acceptor was studied with admittance spectroscopy and showed Meyer-Neldel behaviour. This indicates that the entropy significantly contributes to the activation energy. Published by AIP Publishing.

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“…Drive level capacitance profiling (DLCP) and capacitance-voltage (CV) measurements (taken at 25° C) follow the procedures described by Heath et al [23] with measurements taken at 2×10 5 Hz for V AC from 20-380 mV. The relative dielectric of CZTSSe and ACZTSe (5% Ag) is taken to be 8.5ε 0 from previous admittance measurements of nanocrystal based CZTSSe [24]. Minimal light-soaking effects were observed in the capacitance response.…”

Section: Methodsmentioning

confidence: 99%

Optoelectronic and material properties of nanocrystal-based CZTSe absorbers with Ag-alloying

Hages

Koeper

Agrawal

2016

Solar Energy Materials and Solar Cells

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127

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In this work, the benefits of Ag-alloying in kesterite solar cells are explored in terms of tunable band gap, improved grain growth, improved minority carrier lifetime, reduced defect formation, and reduced potential fluctuations for (Ag,Cu) 2 ZnSnSe 4 (ACZTSe) absorbers relative to Cu 2 ZnSnSe 4 (CZTSe). The enhanced optoelectronic properties are shown to scale here with the degree of Ag-alloying in ACZTSe. The impacts of these effects on device performance are discussed, with improvement in average device performance/open-circuit voltage reported for ACZTSe (5%-Ag) absorbers relative to CZTSe absorbers with similar band gap. These initial results are promising for the Ag-alloyed ACZTSe material system as V OC limitations are the primary cause of poor device performance in kesterite solar cells, and cation substitution presents a unique method to tune the defect properties of kesterite absorbers. Herein, nanoparticle synthesis and large-grain ACZTSe absorber formation is described followed by material and optoelectronic characterization. Additionally, RTP processing is presented to achieve fully selenized large-grain chalcogenide absorbers from sulfide nanocrystal inks.In addition to modification of the defect properties, Ag-alloying may also be beneficial for band gap tuning/grading of the absorber for improved performance. For CZTSSe, the absorber band gap (E G ) is determined mainly by Cu d orbital and S/Se p orbital anti-bonding (valance band maximum -VBM) and Sn s orbital and S/Se sp

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Device comparison of champion nanocrystal-ink based CZTSSe and CIGSSe solar cells: Capacitance spectroscopy

Cited by 11 publications

References 21 publications

Identifying the Real Minority Carrier Lifetime in Nonideal Semiconductors: A Case Study of Kesterite Materials

Identifying the Real Minority Carrier Lifetime in Nonideal Semiconductors: A Case Study of Kesterite Materials

Impact of annealing on electrical properties of Cu2ZnSnSe4 absorber layers

Optoelectronic and material properties of nanocrystal-based CZTSe absorbers with Ag-alloying

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