Interference effects in photoluminescence spectra of Cu2ZnSnS4 and Cu(In,Ga)Se2 thin films

Larsen, Jes K.; Li, Shuyi; Scragg, Jonathan J.; Ren, Yi; Hägglund, Carl; Heinemann, Marc Daniel; Kretzschmar, Steffen; Unold, Thomas; Platzer‐Björkman, Charlotte

doi:10.1063/1.4926857

Cited by 47 publications

(45 citation statements)

References 34 publications

(38 reference statements)

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“…10, corresponds to to the inflection point of the EQE curve. The PL spectrum has a peak at a lower energy (1.32 eV), similarly to previous investigations on CZTS devices [9,39]. This is believed to be due to a high density of band-edge tail states that reduces the achievable open circuit voltage [26].…”

Section: Electrical and Optical Propertiessupporting

confidence: 79%

Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

Cazzaniga

Crovetto

Yan

et al. 2017

Solar Energy Materials and Solar Cells

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We report on the fabrication of a 5.2% efficiency Cu 2 ZnSnS 4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed. At the optimal laser fluence, amorphous CZTS precursors with optimal stoichiometry for solar cells are deposited from a single target. Such precursors do not result in detectable segregation of secondary phases after the subsequent annealing step. In the analysis of the solar cell device, we focus on the effects of the finite thickness of the absorber layer. Depletion region width, carrier diffusion length, and optical losses due to incomplete light absorption and back contact reflection are quantified. We conclude that material-and junction quality is comparable to that of thicker state-of-the-art CZTS devices, even though the efficiency is lower due to optical losses.

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Section: Electrical and Optical Propertiessupporting

confidence: 79%

Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

Cazzaniga

Crovetto

Yan

et al. 2017

Solar Energy Materials and Solar Cells

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“…The presence of multiple peaks is apparent; however, these coincide with interference fringes in the reflectance spectrum, so we ascribe them to a measurement artefact (this is discussed in detail in Ref. ). As illustrated in the Supporting Information, the interference fringes can be mathematically removed from the spectrum.…”

Section: Resultsmentioning

confidence: 93%

“…Example Gaussian fits (which closely approximate the actual PL response, see Ref. ) are shown for the 110 and 350 °C spectra, and the fitted peak positions are indicated by the vertical dashes.…”

Section: Resultsmentioning

confidence: 95%

Cu–Zn disorder and band gap fluctuations in Cu₂ZnSn(S,Se)₄: Theoretical and experimental investigations

Scragg

Larsen

Kumar

et al. 2015

Physica Status Solidi (b)

194

171

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Phone: þ46 (0) 18 471 3382, Fax: þ46 (0) 18 555 095Cu 2 ZnSn(S,Se) 4 (CZTS(e)) solar cells suffer from low-opencircuit voltages that have been blamed on the existence of band gap fluctuations, with different possible origins. In this paper, we show from both theoretical and experimental standpoints that disorder of Cu and Zn atoms is in all probability the primary cause of these fluctuations. First, quantification of Cu-Zn disorder in CZTS thin films is presented. The results indicate that disorder is prevalent in the majority of practical samples used for solar cells. Then, ab initio calculations for different arrangements and densities of disorder-induced [Cu Zn þ Zn Cu ] defect pairs are presented and it is shown that spatial variations in band gap of the order of 200 meV can easily be caused by Cu-Zn disorder, which would cause large voltage losses in solar cells. Experiments using Raman spectroscopy and room temperature photoluminescence combined with in situ heat-treatments show that a shift in the energy of the dominant band-to-band recombination pathway correlates perfectly to the order-disorder transition, which clearly implicates Cu-Zn disorder as the cause of band gap fluctuations in CZTS. Our results suggest that elimination or passivation of Cu-Zn disorder could be very important for future improvements in the efficiency of CZTS(e)-based solar cells.

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“…This quantity is on the order of a few percent for good quality absorber layers [50][77] [78] and is directly linked to the quasi Fermi level splitting and the implied voltage of a solar cell. [79][80] On a side note it should be mentioned that the interpretation of PL spectra can be impeded by thin film interference effects, [81] [82] insufficient background correction as well as drifting spectrometer calibrations.…”

Section: Photoluminescencementioning

confidence: 99%

Optical Absorption‐Based In Situ Characterization of Halide Perovskites

Babbe

Sutter‐Fella

2020

Advanced Energy Materials

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Halide perovskites have emerged as materials for high-performance optoelectronic devices. Often, progress made to date in terms of higher efficiency and stability is based on increasing material complexity that is, formation of multicomponent halide perovskites with multiple cations and anions. In this review article, the use of in situ optical methods, namely photoluminescence (PL) and UV-Vis, that provide access to the relevant time-and length-scales to ascertain chemistry-property relationships by monitoring evolving properties is discussed. Additionally, because halide perovskites are electron-ion conductors and prone to solid-state ion transport under various external stimuli application of these optical methods in the context of ionic movement, is described to reveal mechanistic insights. Finally, examples of using in situ PL and UV-Vis to study degradation and phase transitions are reviewed to demonstrate the wealth of information that can be obtained regarding many different aspects of ongoing research activities in the field of halide perovskites.

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Interference effects in photoluminescence spectra of Cu2ZnSnS4 and Cu(In,Ga)Se2 thin films

Abstract: Fabrication of Cu2ZnSnS4 thin films on flexible polyimide substrates by sputtering and post-sulfurization J. Renewable Sustainable Energy 6, 053110 (2014)

Cited by 47 publications

References 34 publications

Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

Cu–Zn disorder and band gap fluctuations in Cu₂ZnSn(S,Se)₄: Theoretical and experimental investigations

Optical Absorption‐Based In Situ Characterization of Halide Perovskites

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Interference effects in photoluminescence spectra of Cu2ZnSnS4 and Cu(In,Ga)Se2 thin films

Abstract: Fabrication of Cu2ZnSnS4 thin films on flexible polyimide substrates by sputtering and post-sulfurization J. Renewable Sustainable Energy 6, 053110 (2014)

Cited by 47 publications

References 34 publications

Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

Cu–Zn disorder and band gap fluctuations in Cu2ZnSn(S,Se)4: Theoretical and experimental investigations

Optical Absorption‐Based In Situ Characterization of Halide Perovskites

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Product

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Cu–Zn disorder and band gap fluctuations in Cu₂ZnSn(S,Se)₄: Theoretical and experimental investigations