Browsing by Author "Han, Jiye"

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Large-Diameter Carbon Nanotube Transparent Conductor Overcoming Performance–Yield Tradeoff
(2022-03-09) Zhang, Qiang; Nam, Jeong Seok; Han, Jiye; Datta, Sukanta; Wei, Nan; Ding, Er Xiong; Hussain, Aqeel; Ahmad, Saeed; Skakalova, Viera; Khan, Abu Taher; Liao, Yong Ping; Tavakkoli, Mohammad; Peng, Bo; Mustonen, Kimmo; Kim, Dawoon; Chung, In; Maruyama, Shigeo; Jiang, Hua; Jeon, Il; Kauppinen, Esko I.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The floating catalyst chemical vapor deposition (FCCVD) method for producing single-walled carbon nanotubes (SWNTs) has demonstrated great potential in transparent conductive film (TCF) application. In FCCVD, reducing the concentration of carbon nanotubes (CNTs) is a well-agreed method of improving the conductivity of SWNT TCF, achieved by producing thinner and longer CNT bundles. However, this method decreases the yield dramatically, which has persisted throughout the TCF development. Here, the production of large-diameter double-walled CNT (DWNT) TCFs via FCCVD is reported, which overcomes the tradeoff between performance and yield. These TCFs of DWNTs with an average diameter of approximate to 4 nm have a low sheet resistance of 35 omega sq(-1) at 90% transmittance. The conductivity here aligns with the best-performing SWNT TCFs reported to date, showing a production yield greater than two orders of magnitude. The main factor contributing to the high performance and yield is considered to be the large tube diameter, which greatly improves the yield threshold of CNT bundling and leads to long tube length and unique junctions broadening. Moreover, the application of DWNT TCFs in perovskite solar cells exhibits a power conversion efficiency of 17.4%, which has not been reported yet in indium-free CNT-based solar cells.
Semi-transparent metal electrode-free all-inorganic perovskite solar cells using floating-catalyst-synthesized carbon nanotubes
(2024-03) Yoon, Saemon; Lee, Il Hyun; Han, Jiye; Bahadur, Jitendra; Lee, Seojun; Lee, Sangsu; Kim, Dong Suk; Mikladal, B.; Kauppinen, Esko I.; Kang, Dong Won; Jeon, Il
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Perovskite solar cells offer a promising future for next-generation photovoltaics owing to numerous advantages such as high efficiency and ease of processing. However, two significant challenges, air stability, and manufacturing costs, hamper their commercialization. This study proposes a solution to these issues by introducing a floating catalyst-based carbon nanotube (CNT) electrode into all-inorganic perovskite solar cells for the first time. The use of CNT eliminates the need for metal electrodes, which are primarily responsible for high fabrication costs and device instability. The nanohybrid film formed by combining hydrophobic CNT with polymeric hole-transporting materials acted as an efficient charge collector and provided moisture protection. Remarkably, the metal-electrode-free CNT-based all-inorganic perovskite solar cells demonstrated outstanding stability, maintaining their efficiency for over 4000 h without encapsulation in air. These cells achieved a retention efficiency of 13.8%, which is notable for all-inorganic perovskites, and they also exhibit high transparency in both the visible and infrared regions. The obtained efficiency was the highest for semi-transparent all-inorganic perovskite solar cells. Building on this, a four-terminal tandem device using a low-band perovskite solar cell achieved a power conversion efficiency of 21.1%. These CNT electrodes set new benchmarks for the potential of perovskite solar cells with groundbreaking device stability and tandem applicability, demonstrating a step toward industrial applications. (Figure presented.).
Upcycled synthesis and extraction of carbon-encapsulated iron carbide nanoparticles for gap Plasmon applications in perovskite solar cells
(2023-06) Han, Jiye; Kim, Kyusun; Tavakkoli, Mohammad; Lee, Jongmin; Kim, Dawoon; Chung, In; Lee, Aram; Park, Keonwoo; Liao, Yongping; Lee, Jin Wook; Lee, Seoung Ki; Oh, Jin Woo; Sung, Hyokyung; Kauppinen, Esko; Jeon, Il
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
An effective method for obtaining large amounts of metal nanoparticles (NPs) encapsulated by carbon layers through upcycling from floating-catalyst aerosol chemical vapor-deposited carbon nanotubes is demonstrated. NPs with diameters of less than 20 μm are selectively extracted from the synthesized carbon assortments through sonication, centrifugation, and filtration. The particles show an aggregation behavior owing to the π–π interaction between the graphitic carbon shells surrounding the iron carbides. By controlling the degree of the aggregation and arrangement, the light scattering by the gap-surface plasmon effect in perovskite solar cells is maximized. Application of the NPs to the devices increased the power conversion efficiency from 19.71% to 21.15%. The short-circuit current density (JSC) trend over the particle aggregation time accounts for the plasmonic effect. The devices show high stability analogue to the control devices, confirming that no metal-ion migration took place thanks to the encapsulation. (Figure presented.).
Utilization of Multifunctional Environment-Friendly Organic Dopants Inspired from Nature for Carbon Nanotube-Based Planar Heterojunction Silicon Solar Cells
(2022-05) Han, Jiye; Nam, Jeong Seok; Seo, Seungju; Lee, Aram; Lee, Changhyun; Park, Sangeun; Kang, Yoonmook; Lee, Hae Seok; Kim, Donghwan; Zhang, Qiang; Sung, Hyokyung; Kauppinen, Esko; Jeong, Hyuck; Oh, Jin Woo; Maruyama, Shigeo; Jung, Im Doo; Jeon, Il
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Herein, eco-friendly natural acids inspired by nature, namely, acetic acid, formic acid, lactic acid, and citric acid on their capability of functioning as a p-dopant for the carbon nanotube transparent electrode in silicon-based planar heterojunction solar cells, are tested. From the result, lactic acid shows the multifunctional effect of p-doping with excellent doping stability as well as antireflection. The doping effect and its stability are investigated by diverse methods, such as van der Pauw four-probe measurement as well as Raman, photoelectron yield, and absorption spectroscopy. The sheet resistance decreases by 22.1% when carbon nanotube films are doped by lactic acid and the doped films are stable for more than 20 days. The antireflection effect of lactic acid coating is confirmed by atomic force microscopy, ellipsometry, computational analyses, and reflectance spectroscopy. The power conversion efficiency of carbon nanotube-laminated silicon solar cells improves from 8.2% to 10.3% by using nature-inspired lactic acid. Such a great improvement is ascribed to not only the p-doping and antireflection effects but also the passivation effect of lactic acid on the Si surface defect sites as evidenced by both the Fourier-transform infrared and the Quasi-steady-state photoconductance lifetime measurements.