Impact of Post-Deposition Recrystallization by Alkali Fluorides on Cu(In,Ga)Se2Thin-Film Materials and Solar Cells

Rajan, Grace; Belfore, Benjamin; Karki, Shankar; Poudel, Deewakar; Kahoui, Hamza; Lanham, Nicole; Palmiotti, Elizabeth; Soltanmohammad, Sina; Rockett, Angus; Marsillac, Sylvain

doi:10.1016/j.tsf.2019.137526

Cited by 20 publications

(8 citation statements)

References 21 publications

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“…Interestingly, the overall composition of the films did not change with the recrystallization process. Because of the low temperature and high deposition rates used, the devices fabricated did not reach as high efficiency as we would normally get [16,17], but interesting trends could be seen. As is usual with CIGS solar cells, and with many other devices, competing properties can yield better or worse efficiency.…”

Section: Discussionmentioning

confidence: 95%

In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

et al. 2021

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Cu(In,Ga)Se2 (or CIGS) thin films and devices were fabricated using a modified three-stage process. Using high deposition rates and a low temperature during the process, a copper chloride vapor treatment was introduced in between the second and third stages to enhance the films properties. X-ray diffraction and scanning electron microscopy demonstrate that drastic changes occur after this recrystallization process, yielding films with much larger grains. Secondary ion mass spectrometry shows that the depth profile of many elements is not modified (such as Cu, In and Se) while others change dramatically (such as Ga and Na). Because of the competing effects of these changes, not all parameters of the solar cells are enhanced, yielding an increase of 15% in the device efficiency at the most.

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Section: Discussionmentioning

confidence: 95%

In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

et al. 2021

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“…Their properties explain why alkali fluoride post-deposition treatments passivate defects but do not result in grain growth. 16 T A B L E 1 Composition results collected by EDS for the CIGS film deposited at 350 C and after treatments with InBr…”

Section: Thermodynamic Evaluationmentioning

confidence: 99%

“…Alkali halide postdeposition treatments have been shown to passivate defects and improve low-temperature (350 C) deposited CIGS films; however, large grains did not form. 16 We have shown that the use of a metal halide transport agent can both recrystallize and improve the grain size of low-temperature, high-rate deposited CIGS with varying changes to composition. [17][18][19][20][21][22] By studying the thermodynamic behaviors of various metal halides with respect to experimental conditions and results, the treatments can be better optimized, understood, and interpreted.…”

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confidence: 96%

A thermodynamic evaluation of metal halides for the recrystallization of Cu(In,Ga)Se₂

Palmiotti

Marsillac

Rockett

2022

Progress in Photovoltaics

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CdTe films are deposited at low temperatures and recrystallized to photovoltaic device quality using CdCl2 treatments, leading to competitive manufacturing costs. Cu(In,Ga)Se2 (CIGS) typically requires high‐temperature, low‐rate depositions to produce high‐efficiency devices, resulting in higher costs. A similar metal halide treatment of CIGS has been demonstrated by us previously for some metal halide sources. To understand and optimize the process, a thermodynamic evaluation of candidate metal halides for such treatments is presented as a guide for their selection. By comparing bond dissociation energies, mono‐ and di‐halide compounds are proposed to be ideal compounds to act as transport agents. Known recrystallization and temperature reduction benefits by Ag alloying suggest that Ag halides should be used to aid transport of all species. The high vapor pressure and mobility of Ga compounds still pose a problem for metal halide treatment, resulting in Ga etching and removal of intentional Ga gradients. Less severe but similar issues with In compounds may occur. Cu compounds have low vapor pressures that may limit transport; however, Cu is highly mobile in CIGS, and recrystallization still occurs.

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“…It is therefore likely that this change in Ga profile was related to the change in grain size and reordering of the elemental matrix, as seen by XRD and SEM. It is also possible that selenium acted as a fluxing agent along with Na [14], redistributing slightly the Ga at the surface. Indeed, XRF indicated that the overall composition did not change.…”

Section: Post-deposition Recrystallization At 500 °Cmentioning

confidence: 99%

“…possible that selenium acted as a fluxing agent along with Na [14], redistributing slightly the Ga at the surface. Indeed, XRF indicated that the overall composition did not change.…”

Section: Post-deposition Recrystallization At 500 °Cmentioning

confidence: 99%

Analysis of Post-Deposition Recrystallization Processing via Indium Bromide of Cu(In,Ga)Se2 Thin Films

et al. 2021

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Cu(In,Ga)Se2 (CIGS) thin films were deposited at low temperature (350 °C) and high rate (10 µm/h) by a single stage process. The effect of post-deposition treatments at 400 °C and 500 °C by indium bromide vapor were studied and compared to the effect of a simple annealing under selenium. Structural, electrical, and chemical analyses demonstrate that there is a drastic difference between the different types of annealing, with the ones under indium bromide leading to much larger grains and higher conductivity. These properties are associated with a modification of the elemental profiles, specifically for gallium and sodium.

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Impact of Post-Deposition Recrystallization by Alkali Fluorides on Cu(In,Ga)Se2Thin-Film Materials and Solar Cells

Cited by 20 publications

References 21 publications

In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

A thermodynamic evaluation of metal halides for the recrystallization of Cu(In,Ga)Se₂

Analysis of Post-Deposition Recrystallization Processing via Indium Bromide of Cu(In,Ga)Se2 Thin Films

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Impact of Post-Deposition Recrystallization by Alkali Fluorides on Cu(In,Ga)Se2Thin-Film Materials and Solar Cells

Cited by 20 publications

References 21 publications

In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

A thermodynamic evaluation of metal halides for the recrystallization of Cu(In,Ga)Se2

Analysis of Post-Deposition Recrystallization Processing via Indium Bromide of Cu(In,Ga)Se2 Thin Films

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A thermodynamic evaluation of metal halides for the recrystallization of Cu(In,Ga)Se₂