Kesterite solar-cells by drop-casting of inorganic sol–gel inks

Tseberlidis, Giorgio; Trifiletti, Vanira; Donne, A. Le; Frioni, Luigi; Acciarri, M.; Binetti, S.

doi:10.1016/j.solener.2020.07.093

Cited by 17 publications

(9 citation statements)

References 25 publications

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“…Moreover, it points out a good bulk nature with few recombinations at this level, suggesting that low efficiency is mainly related to recombination that takes place probably at the interfaces. In particular, this issue is related to the back contact due to the bulky MoS 2 presence already described in other works of our research group , and to the well-known bulk features typical of the kesterite phase and also revealed by PL analysis …”

Section: Results and Discussionsupporting

confidence: 66%

“…This feature, already detected also in the SEM cross-sectional image ( Figure 5 b), is the proof of the charge extraction problems already supposed previously in this work and also encountered and detected by fitting and simulations in previous works of the research group on samples grown under similar conditions. 11 , 25 Therefore, despite the pure-phase absorber production with the desired optical and morphological properties, the resulting insulating MoS 2 layer generated by the heavy back contact sulfurization hinders the proper charge extraction from the device.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Moreover, 0.04 M KCl was added to help with the grain growth and passivation, as well as to minimize the voids and lead to a more compact morphology of the material, having already proved and described recently the beneficial effect of this procedure on CZTS samples prepared with the same methodology. 25 In fact, during the annealing, KCl converts into K 2 S, helping the coalescence of vicinal grains and thus leading to a more compact material. 32 In Figure 5a, it is possible to appreciate the morphology improvement, thanks to the KCl addition, where the material results more compact and with respectable grain dimensions ranging between 400 nm and 1 μm.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In this work, we wanted to deeply investigate the nature of the pure sulfide alloy, leading to high energy gaps, to provide new outcomes for the tandem PV application field. To do so, we adapted our simple methodology, recently described elsewhere, , to produce a small library of CZTGS samples with different tin–germanium contents to fine-tune the band gap of the material for the future tandem device applications. This procedure allowed us to avoid industrially nonappealing deposition machines and prevent the wastage of raw materials compared to other techniques.…”

Section: Introductionmentioning

confidence: 99%

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Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

et al. 2022

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In the last few decades, the attention of scientific community has been driven toward the research on renewable energies. In particular, the photovoltaic (PV) thin-film technology has been widely explored to provide suitable candidates as top cells for tandem architectures, with the purpose of enhancing current PV efficiencies. One of the most studied absorbers, made of earth-abundant elements, is kesterite Cu 2 ZnSnS 4 (CZTS), showing a high absorption coefficient and a band gap around 1.4–1.5 eV. In particular, thanks to the ease of band-gap tuning by partial/total substitution of one or more of its elements, the high-band-gap kesterite derivatives have drawn a lot of attention aiming to find the perfect partner as a top absorber to couple with silicon in tandem solar cells (especially in a four-terminal architecture). In this work, we report the effects of the substitution of tin with different amounts of germanium in CZTS-based solar cells produced with an extremely simple sol–gel process, demonstrating how it is possible to fine-tune the band gap of the absorber and change its chemical–physical properties in this way. The precursor solution was directly drop-cast onto the substrate and spread with the aid of a film applicator, followed by a few minutes of gelation and annealing in an inert atmosphere. The desired crystalline phase was obtained without the aid of external sulfur sources as the precursor solution contained thiourea as well as metal acetates responsible for the in situ coordination and thus the correct networking of the metal centers. The addition of KCl in dopant amounts to the precursor solution allowed the formation of well-grown compact grains and enhanced the material quality. The materials obtained with the optimized procedure were characterized in depth through different techniques, and they showed very good properties in terms of purity, compactness, and grain size. Moreover, solar-cell prototypes were produced and measured, exhibiting poor charge extraction due to heavy back-contact sulfurization as studied in depth and experimentally demonstrated through Kelvin probe force microscopy.

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Section: Results and Discussionsupporting

confidence: 66%

Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

et al. 2022

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“…As shown by EDX analysis, all samples exhibit a non-stoichiometric distribution of Cu and Zn atoms in the CZTS structure, containing a small amount of copper (Cu/(Zn + Sn) = 0.82–0.87) and an excess of Zn (Zn/Sn = 1.04–1.14). This non-stoichiometric distribution has been shown to promote the formation of secondary phases, defects and vacancies in CZTS films 28 , 29 ; on the other hand it is beneficial for enhanced charge carrier transport and solar cell performance 30 , 31 . In addition, a certain amount of chlorine is also present in the CZTS material (see Table S1 ).…”

Section: Resultsmentioning

confidence: 99%

Improvement of CZTSSe film quality and superstrate solar cell performance through optimized post-deposition annealing

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Selskis

et al. 2022

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Improving the performance of kesterite solar cells requires high-quality, defect-free CZTS(Se) films with a reduced number of secondary phases and impurities. Post-annealing of the CZTS films at high temperatures in a sulfur or selenium atmosphere is commonly used to improve the quality of the absorbing material. However, annealing at high-temperatures can promote material decomposition, mainly due to the loss of volatile elements such as tin or sulfur. In this work, we investigate how the additional step of sulfurization at reduced temperatures affects the quality and performance of CZTSSe based solar cells. A comprehensive structural analysis using conventional and high resolution XRD as well as Raman spectroscopy revealed that the highest CZTSSe material quality with the lowest structural disorder and defect densities was obtained from the CZTS films pre-sulfurized at 420 °C. Furthermore, we demonstrate the possibility of using Sb2Se3 as a buffer layer in the superstrate configuration of CZTSSe solar cells, which is possible alternative to replace commonly employed toxic CdS as a buffer layer. We show that the additional low-temperature selenization process and the successful use of Sb2Se3 as a buffer layer could improve the performance of CZTSSe-based solar cells by up to 3.48%, with an average efficiency of 3.1%.

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Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large‐Area Fabrication

et al. 2022

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large-area fabrication without compromising the power conversion efficiency (PCE) always comes with new and unexpected challenges even for well-studied and well-optimized laboratory-scale PV technologies. For instance, non-concentrated monocrystalline silicon solar cells have reached a record 26.1% PCE, [1] but the efficiencies of most recent commercial panels are typically only up to about 22% (e.g., SunPower's Maxeon 3 panels: 22.8%, LG's Neon R: 22%, Panasonic's EverVolt: 21.7%). [2] Apart from the technical challenges, cost is the main driving factor for industry when it comes to production of modules or panels by scaling up laboratory-scale research cells. Low-cost PV technologies with performance comparable to existing industrial PV technologies may help in achieving the desired cost target, and perovskite solar cell (PSC) technology is the most suitable candidate in the current scenario. [3] The last decade saw a monumental rise in PSC technology. The perovskite absorber naturally possesses most of the desired properties for highly efficient solar cells, such as long carrier diffusion length, high carrier mobility, high light absorption coefficient, and excellent defect-tolerance. [4] Both in terms of laboratory-scale research cells and large-area panels, PSCs have seen a steep rise in PCE, reaching 25.8% for research cells, [1] and 17.9% for large-area modules with size of 802 cm 2 . [2] Further, PSC processing is relatively simple and Colloidally grown nanosized semiconductors yield extremely high-quality optoelectronic materials. Many examples have pointed to near perfect photoluminescence quantum yields, allowing for technology-leading materials such as high purity color centers in display technology. Furthermore, because of high chemical yield, and improved understanding of the surfaces, these materials, particularly colloidal quantum dots (QDs) can also be ideal candidates for other optoelectronic applications. Given the urgent necessity toward carbon neutrality, electricity from solar photovoltaics will play a large role in the power generation sector. QDs are developed and shown dramatic improvements over the past 15 years as photoactive materials in photovoltaics with various innovative deposition properties which can lead to exceptionally low-cost and high-performance devices. Once the key issues related to charge transport in optically thick arrays are addressed, QD-based photovoltaic technology can become a better candidate for practical application. In this article, the authors show how the possibilities of different deposition techniques can bring QD-based solar cells to the industrial level and discuss the challenges for perovskite QD solar cells in particular, to achieve largearea fabrication for further advancing technology to solve pivotal energy and environmental issues.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202107888.

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Kesterite solar-cells by drop-casting of inorganic sol–gel inks

Cited by 17 publications

References 25 publications

Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

Improvement of CZTSSe film quality and superstrate solar cell performance through optimized post-deposition annealing

Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large‐Area Fabrication

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