Correlative microscopy and monitoring of segregation processes in optoelectronic semiconductor materials and devices

Abou‐Ras, Daniel; Bloeck, Ulrike; Caicedo‐Dávila, Sebastián; Eljarrat, Alberto; Funk, Hannah; Hammud, Adnan; Thomas, Sinju; Wargulski, Dan R.; Lunkenbein, Thomas; Koch, Christoph T.

doi:10.1063/5.0138952

Cited by 4 publications

(2 citation statements)

References 58 publications

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“…Slight morphological changes are visible. A multivariate algorithm , was used to identify and map the structural information from the local atomic structure. Several diffraction patterns were acquired during the time series (Figure b); all of these patterns were assigned successfully to the CsPb(Br 0.8 I 0.2 ) 3 phase by determining the interplanar distances from the reflection positions.…”

Section: Resultsmentioning

confidence: 99%

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Phase Segregation Mechanisms in Mixed-Halide CsPb(Br_xI_1–x)₃ Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Funk,

Binyamin,

Etgar

et al. 2023

ACS Mater. Au

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Phase segregation in inorganic CsPb(Br x I1–x )3 nanoparticles (NPs) exhibiting originally a homogeneous [Br]:[I] mixture was investigated by means of in situ transmission electron microscopy (TEM) and evaluated by using multivariate analyses. The colloidal synthesis of the NPs offers good control of the halide ratios on the nanoscale. The spatially resolved TEM investigations were correlated with integral photoluminescence measurements. By this approach, the halide-segregation processes and their spatial distributions can be described as being governed by the interaction of three partial processes: electron- and photon-irradiation-induced iodide oxidation, local differences in band gap energy, and intrinsic lattice strain. Since the oxidation can be induced by both electron-beam and light irradiation, both irradiation types can induce phase segregation in CsPb(Br x I1–x )3 compounds. This makes in situ TEM a valuable tool to monitor phase transformation in corresponding NPs and thin films on the sub-nm scale.

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Section: Resultsmentioning

confidence: 99%

“…ICA is a special case of a blind source separation and is widely used in digital image processing. For more details on this approach, the reader is referred to refs ( 50 ) and ( 55 ).…”

Section: Experimental Methodsmentioning

confidence: 99%

Phase Segregation Mechanisms in Mixed-Halide CsPb(Br_xI_1–x)₃ Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Funk,

Binyamin,

Etgar

et al. 2023

ACS Mater. Au

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Role of Ag Addition on the Microscopic Material Properties of (Ag,Cu)(In,Ga)Se₂ Absorbers and Their Effects on Losses in the Open‐Circuit Voltage of Corresponding Devices

Thomas,

Witte,

Hariskos

et al. 2024

Progress in Photovoltaics

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Ag alloying of Cu(In,Ga)Se2 (CIGSe) absorbers in thin‐film solar cells leads to improved crystallization of these absorber layers at lower substrate temperatures than for Ag‐free CIGSe thin films as well as to enhanced cation interdiffusion, resulting in reduced Ga/In gradients. However, the role of Ag in the microscopic structure–property relationships in the (Ag,Cu)(In,Ga)Se2 thin‐film solar cells as well as a correlation between the various microscopic properties of the polycrystalline ACIGSe absorber and open‐circuit voltage of the corresponding solar cell device has not been reported earlier. In the present work, we study the effect of Ag addition by analyzing the differences in the various bulk, grain‐boundary, optoelectronic, emission, and absorption‐edge properties of ACIGSe absorbers with that of a reference CIGSe absorber. By comparing thin‐film solar cells with similar band‐gap energies ranging from about 1.1 to about 1.2 eV, we were able to correlate the differences in their absorber material properties with the differences in the device performance of the corresponding solar cells. Various microscopic origins of open‐circuit voltage losses were identified, such as strong Ga/In gradients and local compositional variations within individual grains of ACIGSe layers, which are linked to absorption‐edge broadening, lateral fluctuations in luminescence‐energy distribution, and band tailing, thus contributing to radiative VOC losses. A correlation established between the effective electron lifetime, average grain size, and lifetime at the grain boundaries indicates that enhanced nonradiative recombination at grain boundaries is a major contributor to the overall VOC deficit in ACIGSe solar cells. Although the alloying with Ag has been effective in increasing the grain size and the effective electron lifetime, still, the Ga/In gradients and the grain‐boundary recombination in the ACIGSe absorbers must be reduced further to improve the solar‐cell performance.

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Silver Metallization with Controlled Etch Stop Using SiO_x Layers in Passivating Contacts for Improved Silicon Solar Cell Performance

Glatthaar,

Schmidt,

Hammud

et al. 2023

Solar RRL

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Metallization of polycrystalline‐silicon/silicon oxide (poly‐Si/SiOx) passivating contacts with fire‐through silver paste is a crucial process for implementation of passivating contacts in industrial manufacturing of solar cells. For a microscopic understanding of the metallization process, the contact forming interface between the Ag crystallites and the poly‐Si layer is investigated with high‐resolution transmission electron microscopy. For this purpose, multilayer atmospheric pressure chemical vapor deposition poly‐Si samples with a SiOx layer between the individual poly‐Si layers are fabricated, screen printed with a lead‐free Ag paste, and contact fired. Electron micrographs show that in this process the etching of the paste and the subsequent Ag crystallite formation is stopped by this interface with the SiOx layer. Additionally, energy‐dispersive X‐Ray mapping reveals the presence of an oxide layer around the Ag crystallites. This finding differs significantly from well‐investigated classical cell concepts with contact formation on diffused crystalline silicon. Moreover, an analysis of the Ag crystallite orientation in correlation to the neighboring Si crystallite orientation indicates no direct relationship. Finally, it is shown that the use of this multilayer approach is favorable for integration into a solar cell concept leading to a higher passivation quality at the metallized area and lower contact resistivity.

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Correlative microscopy and monitoring of segregation processes in optoelectronic semiconductor materials and devices

Cited by 4 publications

References 58 publications

Phase Segregation Mechanisms in Mixed-Halide CsPb(Br_xI_1–x)₃ Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Phase Segregation Mechanisms in Mixed-Halide CsPb(Br_xI_1–x)₃ Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Role of Ag Addition on the Microscopic Material Properties of (Ag,Cu)(In,Ga)Se₂ Absorbers and Their Effects on Losses in the Open‐Circuit Voltage of Corresponding Devices

Silver Metallization with Controlled Etch Stop Using SiO_x Layers in Passivating Contacts for Improved Silicon Solar Cell Performance

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Correlative microscopy and monitoring of segregation processes in optoelectronic semiconductor materials and devices

Cited by 4 publications

References 58 publications

Phase Segregation Mechanisms in Mixed-Halide CsPb(BrxI1–x)3 Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Phase Segregation Mechanisms in Mixed-Halide CsPb(BrxI1–x)3 Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Role of Ag Addition on the Microscopic Material Properties of (Ag,Cu)(In,Ga)Se2 Absorbers and Their Effects on Losses in the Open‐Circuit Voltage of Corresponding Devices

Silver Metallization with Controlled Etch Stop Using SiOx Layers in Passivating Contacts for Improved Silicon Solar Cell Performance

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Phase Segregation Mechanisms in Mixed-Halide CsPb(Br_xI_1–x)₃ Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Phase Segregation Mechanisms in Mixed-Halide CsPb(Br_xI_1–x)₃ Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Role of Ag Addition on the Microscopic Material Properties of (Ag,Cu)(In,Ga)Se₂ Absorbers and Their Effects on Losses in the Open‐Circuit Voltage of Corresponding Devices

Silver Metallization with Controlled Etch Stop Using SiO_x Layers in Passivating Contacts for Improved Silicon Solar Cell Performance