Eg-tuned CIGS for emerging tandem applications
Eg-tuned CIGS for emerging tandem applications
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I-1. Perovskite/CIGS Thin-film Tandem Solar Cell
I-1. Perovskite/CIGS Thin-film Tandem Solar Cell
To surpass the theoretical limits of single-junction solar cells, our group is at the forefront of developing Perovskite/CIGS tandem devices, which stand as one of the most promising architectures in thin-film photovoltaics. This technology synergistically combines a high-bandgap perovskite top cell, excellent at absorbing short-wavelength light, with a low-bandgap CIGS bottom cell, which captures the remaining long-wavelength light.
Our research is strategically focused on two critical areas to maximize tandem performance:
Optimization of Low-Bandgap CIGS Bottom Cells: We are developing advanced processes to create highly efficient and stable low-bandgap (<1.1 eV) CIGS bottom cells, which form the robust foundation of the tandem structure.
Minimization of Interfacial Losses: We are engineering the crucial interconnecting layer between the top and bottom cells to minimize both optical (parasitic absorption) and electrical (recombination and resistance) losses, ensuring that photons and electrons are transferred with maximum efficiency.
This ambitious research is powered by a robust collaborative network with leading domestic research institutions, including Seoul National University, Korea University, Hanyang University, KENTECH, and the Korea Institute of Energy Research (KIER). This spirit of open innovation allows us to accelerate progress and tackle complex challenges from multiple angles.
Our collaborative efforts have culminated in a landmark achievement. In a joint research project with Seoul National University, we successfully fabricated a Perovskite/CIGS tandem solar cell with a world-record conversion efficiency of 26.3%. This monumental achievement has been officially recognized and is now registered on the prestigious Best Research-Cell Efficiency Chart maintained by the National Renewable Energy Laboratory (NREL), cementing our group's position as a global leader in next-generation photovoltaic research. Building on this success, we continue to push the boundaries of what is possible, paving the way for the future of solar energy.
I-2. Wide Eg CIGS Solar Cell for Tandem with Si solar cell
I-2. Wide Eg CIGS Solar Cell for Tandem with Si solar cell
While Perovskite/Silicon tandems have demonstrated high efficiencies, long-term stability remains a critical challenge. Our research focuses on CIGS/Silicon tandems, an architecture that offers a compelling pathway to achieving both high efficiency and the excellent operational stability inherent to CIGS materials.
Realizing this potential requires overcoming two key obstacles: first, suppressing the high charge-carrier recombination losses that have historically limited the voltage of wide-bandgap CIGS cells, and second, fabricating a low-resistance transparent back contact required for the tandem structure.
Our group has developed advanced interface engineering techniques that simultaneously address both challenges. By effectively passivating defects and solving the ITO/CIGS contact resistance issue, we have fabricated a transparent CIGS top cell with world-record performance. This breakthrough provides a viable solution to these longstanding problems, enabling the development of highly stable and efficient tandem devices that can elevate mainstream silicon PV technology to the next level of performance.
I-3. Wide Eg CIGS Solar Cell for all CIGS Tandem PV
I-3. Wide Eg CIGS Solar Cell for all CIGS Tandem PV
An all-chalcopyrite tandem device, created by stacking a high-bandgap CIGS cell atop a low-bandgap one, represents a pinnacle of photovoltaic engineering. This single-material-system approach promises ideal material compatibility and the exceptional long-term stability inherent to CIGS, making it a highly attractive goal for next-generation solar technology.
However, realizing a conventional (monolithic) all-CIGS tandem is hindered by a critical processing bottleneck: the high deposition temperature required for the top CIGS layer is incompatible with the limited thermal stability of the already-completed bottom CIGS cell.
To circumvent this fundamental thermal challenge, our group is pursuing a strategic four-terminal (4T) tandem architecture. In this design, the top and bottom cells are fabricated and optimized independently and then mechanically stacked. This approach effectively decouples the fabrication processes, bypassing the high-temperature issue and providing a practical pathway to realizing this technology.
We are leveraging our world-record, transparent high-bandgap CGSe cells for this purpose, aiming to develop high-performance all-CIGS tandem photovoltaics and open a new frontier for ultra-stable, next-generation solar technology.
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