Particle-less reactive inks

DiGregorio, Steven; Hildreth, Owen

doi:10.1016/b978-0-323-91145-0.00011-6

Cited by 2 publications

(3 citation statements)

References 96 publications

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“…Preliminary investigations indicate that replacing LT-SP with Reactive Silver Ink (RSI) may significantly reduce SHJ silver consumption. , Reactive inks are a conductive ink technology that can produce highly conductive features at low processing temperatures (<100 °C). Instead of metal particles, reactive inks contain dissolved chemical precursors that, when printed, react to form the desired material. − Reactive inks do not require organic stabilizers and capping agents and, therefore, can produce conductive features at lower processing temperatures than their particle-based counterparts. Reactive inks are also simpler to synthesize, have longer shelf lives, and avoid clogging issues compared to nanoparticle inks.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Reactive Silver Ink Formula for Reduced Silver Consumption in Silicon Heterojunction Metallization

DiGregorio

Martinez-Szewczyk

Raikar

et al. 2023

ACS Appl. Energy Mater.

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Silver is the most expensive non-silicon component in photovoltaic cells. This is particularly salient for silicon heterojunction (SHJ) cells, which rely on large quantities of low-temperature silver pastes (LT-SP). SHJ cells would benefit greatly from an industrially scalable metallization process that simultaneously offers low silver consumption, low finger resistivities (<20 μΩ·cm), and low processing temperatures. Printed reactive silver inks (RSI) are an innovative candidate to this end. This work furthers the research on RSI metallization by investigating the impact of ink formula on properties pertinent to SHJ cells, including electrical properties, line width, ink splatter, silver consumption, cell performance, and adhesion. We introduce a scalable, high-throughput flexible needle contact printing approach for metallization that solves many of the issues associated with drop-on-demand printing. The printed silver fingers are characterized using electrical measurements and top-down and cross-sectional microscopy. The best performing ink, consisting of silver acetate, ethylamine, and formic acid, achieved silver fingers with total resistivities of 3.1 μΩ·cm and contact resistivities of 3.2 mΩ·cm2 when printed at 61 °C. This ink metallized a full-sized 156 mm × 156 mm SHJ cell. This is the first reported data for RSI metallization of a full-sized SHJ cell and shows how an optimized RSI can achieve similar performances to LT-SP while consuming 80–90% less silver.

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Section: Introductionmentioning

confidence: 99%

Investigation of Reactive Silver Ink Formula for Reduced Silver Consumption in Silicon Heterojunction Metallization

DiGregorio

Martinez-Szewczyk

Raikar

et al. 2023

ACS Appl. Energy Mater.

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“…In addition to low-temperature processing, reactive inks are advantageous over particle-based inks because they avoid nozzle clogging issues, show higher ink stability, and are easier to synthesize. 20 Reactive inks exist for a range of metals, with reactive silver inks being the most popular due to silver's oxidation resistance and low resistivity. 21,22 Reactive silver inks come in various forms, each with unique characteristics.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Reactive inks are a second type of conductive ink that can produce highly conductive features at temperatures below 100 °C. ,− Instead of metal particles, reactive inks contain dissolved chemical precursors that when printed react to form the desired material. In addition to low-temperature processing, reactive inks are advantageous over particle-based inks because they avoid nozzle clogging issues, show higher ink stability, and are easier to synthesize . Reactive inks exist for a range of metals, with reactive silver inks being the most popular due to silver’s oxidation resistance and low resistivity. , …”

Section: Introductionmentioning

confidence: 99%

Importance of the Heat Treatment Scheme on Self-Reducing Reactive Silver Inks

DiGregorio,

Raikar,

Hildreth

2023

ACS Appl. Electron. Mater.

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Self-reducing reactive silver inks can print high-quality silver at reasonable temperatures. While numerous studies have explored the impact of processing temperature on electrical properties, the role of the heat treatment scheme has not yet been studied. Common heat treatment schemes include printing and drying inks at room temperature before heat treatment, performing heat treatments while the inks are still wet, and directly printing the inks onto heated substrates. Each scheme generates distinct heat transfer and mass transport kinetics that can affect the silver morphology and electrical properties. However, to date, the impact of different schemes has not been systematically investigated. To address this knowledge gap, this work investigates how different heat treatment schemes impact metal formation, sintering, and the resultant electrical properties of printed self-reducing reactive silver inks. Heat treatment on room-temperature dried inks and wet inks, with top-down (oven) and bottom-up (hot plate) heating sources, were compared. Inks dried at room temperature resulted in extremely porous films that required high heat treatment temperatures (>100 °C) for silver densification. However, these dried films could only densify locally, and their high initial porosities resulted in voids and high resistances (∼0.6 Ω mm −1 ) even after heat treatments above 300 °C. Inks that were wet during heat treatment showed moderate improvements in electrical properties with resistances on the order of 0.4 Ω mm −1 at heat treatments of 250 °C. Printing reactive inks directly onto heated substrates yielded the best low-temperature results, with 0.46 Ω mm −1 (5.5 × bulk silver) line resistances achieved at only 90 °C. Overall, this work's experimental results provide detailed insights into why printing onto a heated substrate results in superior electrical performance compared to more common heat treatment schemes. Additionally, controlling where the precipitation reaction occurs is critical to controlling the film morphology and properties. Lastly, this work shows that even an ammonia-based silver reactive ink can achieve good, low-temperature electrical properties with the proper heat treatment scheme.

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Particle-less reactive inks

Cited by 2 publications

References 96 publications

Investigation of Reactive Silver Ink Formula for Reduced Silver Consumption in Silicon Heterojunction Metallization

Investigation of Reactive Silver Ink Formula for Reduced Silver Consumption in Silicon Heterojunction Metallization

Importance of the Heat Treatment Scheme on Self-Reducing Reactive Silver Inks

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