Perovskite Tandem Solar Cells: Key Technology for Next-Generation Solar Cells
Solar power generation is currently playing a crucial role in realizing a carbon-neutral society.
Recently, perovskite tandem solar cells, which can overcome the limitations of existing silicon-based solar cells, are gaining significant attention. This technology has a dual structure combining perovskite and silicon, possessing the potential to greatly enhance efficiency.
In particular, the 'tandem cell' is rapidly advancing, raising expectations for commercialization.
This article will comprehensively explore the basic concepts of perovskite tandem cells, the latest technological trends, and their potential for commercialization.
What is Perovskite?
Perovskite refers to a group of materials with a specific crystal structure, named after the mineral CaTiO₃ found in Russia. The perovskites currently used in solar cells are primarily organic-inorganic hybrid lead halide compounds that have an ABX₃ crystal structure, where A is methylammonium (MA), B is lead (Pb), and X consists of halogen (Cl, Br, I) ions.
These materials possess excellent light absorption capabilities and fast charge carrier transport. Additionally, they can be manufactured at a low cost at low temperatures, making them promising materials to complement or replace existing silicon solar cells. The potential for the utilization of perovskites in the future energy market is considered very high.
One of the main advantages of perovskites is their superior flexibility and processability. This material can be produced in thin film form through solution processes such as spin coating or slot-die coating, making it suitable for flexible solar cells and building-integrated photovoltaics (BIPV) systems.
In particular, perovskite is recognized for its versatility in band gap tuning, allowing complementary light absorption characteristics when forming a tandem structure with silicon, thus being valued as a promising material for tandem cell implementation. These characteristics are expected to significantly contribute to the advancement of solar technology in the future.
Comparison of Silicon Solar Cells vs. Perovskite Tandem Solar Cells
| Category | Conventional Silicon Solar Cells | Perovskite Tandem Solar Cells |
| Max Efficiency (Lab) | About 26.8% (Single Cell World Record) | About 34.6% (Tandem Cell World Record) |
| Module Efficiency (Commercial) | 20~22% (Standard Silicon Modules) | 25~30% (Initial Estimated Module Efficiency) |
| Manufacturing Process | High-Temperature Monocrystalline Silicon Wafer Process (Energy-Intensive) | Low-Temperature Solution Process (Possible Printing/Coating, Simplified Process) |
| Manufacturing Cost | High Wafer Production and Energy Costs | Low Material Costs, Manufacturing Energy about 10% |
| Panel Weight/Form | Thick Glass and Metal Frames (Heavy, Rigid) | Thin and Lightweight (Can Be Coated on Flexible Substrates) |
| Durability (Lifespan) | Verified for over 25 years in outdoor operation (High Stability) | Research on Long-Term Stability Securing in Progress (Improvements Expected in Future) |
Principle of Perovskite and Tandem Cells
Perovskite originates from the crystal structure of calcium titanate (CaTiO₃), primarily used in solar cells as organic-inorganic halide lead (Pb) compounds. This material boasts excellent light absorption and charge mobility, can be produced with low-temperature processes, and has low raw material costs.
Tandem solar cells have a structure that overlays two solar cells that absorb different wavelength ranges. Perovskite absorbs visible light and ultraviolet light, while silicon mainly handles infrared, effectively converting solar energy into electricity. This method has the potential to theoretically achieve efficiencies close to 40%, surpassing the efficiency limits of conventional single silicon cells.
As this innovative technology develops, it is expected to further enhance the efficiency and economics of solar power generation.
Recent Technological Trends and Achievement of World-Class Efficiency
Perovskite tandem cell technology has shown remarkable progress in recent years. In 2022, the German HZB research team attracted attention by achieving a world-leading efficiency of 32.5%. Following that, in 2023, KAUST in Saudi Arabia and LONGi in China recorded efficiencies of 33.7% and 33.9%, respectively, intensifying competition.
By 2024, LONGi achieved an efficiency of 34.6%, surpassing the theoretical limit of conventional single silicon cells known as the Shockley-Queisser limit (about 33.7%). Such advancements are expected to significantly impact the future of solar power technology.
While notable achievements in small-area cells have stood out recently, large-area cell and module technologies are also advancing. Oxford PV in the UK has recorded an efficiency of 28.6% at commercial wafer sizes, while a research team in Korea achieved 20.6% efficiency in 200㎠ cells, showcasing the practicality of large cells. Such developments are brightening the future prospects of solar technology.
Challenges Impeding Commercialization
While perovskite tandem cells show high efficiencies, several challenges must be addressed in the commercialization process. The most significant issues are long-term stability and large-scale production processes. Perovskite materials are sensitive to moisture and oxygen, so encapsulation technology is essential for external use for over 20 years.
Moreover, while small-scale cells can relatively easily be fabricated in laboratories, precise solution coating and stacking techniques are required to uniformly produce large-area modules sized in the range of tens to hundreds of square centimeters. Fortunately, industrial processes like slot-die coating are rapidly developing, increasing optimism for mass production. This technological advancement is expected to have a positive impact on the commercialization of perovskite cells.
Prospects for Commercialization of Perovskite Tandem Cells
Experts predict that the commercialization of perovskite tandem cells will be fully realized between 2025 and 2026. Currently, Oxford PV in the UK is trial-operating mass production lines in Germany, while companies in China and Korea are also conducting trial production. In particular, China is building GW-scale mass production facilities with government support.
Meanwhile, Hanwha Q CELLS in Korea is focusing on technology development targeting mass production by 2026. Research firm Rethink Energy has projected that by 2040, 90% of solar panels worldwide will adopt perovskite technology. Such trends are expected to drive innovation in the solar industry and significantly impact the future energy market.
High Efficiency, Long-Term Stability, and Mass Production: Keys to Commercialization
Perovskite tandem solar cells are gaining attention as a core technology for next-generation solar power generation. In recent years, the efficiency of this technology has rapidly improved, and large-area cell and module technologies are also consistently advancing. However, to enter the commercialization phase, it is necessary to achieve sustainable durability for more than 25 years alongside industrial productivity.
If these technological barriers are overcome and commercialization occurs in 2025 or 2026, the global solar industry will enter a new growth phase. This is expected to bring significant changes to the solar market and positively impact the environmentally friendly energy transition.
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