A high-efficiency, high-stability production technology for Hybrid Perovskite Solar Cells has been developed, maximizing light capture in the near-infrared region
Beyond Visible Light: Perovskite PV Breaks New Ground
Photovoltaic innovation shows no signs of slowing down. The latest breakthrough in the field comes from a collaboration between the Korea Advanced Institute of Science & Technology (KAIST) and Yonsei University, both in South Korea. Scientists have developed new hybrid perovskite solar cells capable of absorbing near-infrared light, thus increasing conversion efficiency compared to traditional perovskite photovoltaics.
To appreciate the significance of this research, however, we need to take a step back.
The Spectrum Issue
Perovskite solar cells are emerging as the new generation of photovoltaics. In a short time, they have achieved performance levels that took crystalline silicon nearly a century to reach. Thanks to their tunable response to different colors within the solar spectrum, they offer a promising path for tandem architectures, and the first perovskite-Si solar panels are already on the market.
However, this class of materials still faces some notable limitations. The most efficient perovskite photovoltaic cells—those based on lead—have an absorption spectrum limited to the visible light region, with a wavelength of 850 nanometers (nm) or less. In other words, they can only harness about 48% of the total solar energy.
Expanding the absorption window would mean capturing a larger amount of energy, thus improving the efficiency of light-to-electricity conversion.
One way to achieve this is by combining different materials, as is done in tandem with silicon today. But let’s take a closer look at the innovation developed by researchers from KAIST and Yonsei University.
The New Hybrid Perovskite Solar Cells
The team has designed and developed a hybrid perovskite device structure with integrated organic photosemiconductors. These materials expanded the absorption range into the near-infrared region (from 0.7 to 10 μm). Additionally, the researchers found a solution to the energy level mismatch at the perovskite/bulk heterojunction (BHJ) organic interface, which typically leads to charge accumulation.
“By introducing a sub-nanometer dipole interface layer, we were able to alleviate the energy barrier between the perovskite and the organic bulk heterojunction, suppress charge buildup, maximize the near-infrared contribution, and improve the current density to 4.9 mA/cm²,” stated a KAIST press release.
The result? Hybrid perovskite solar cells with an internal quantum efficiency (IQE) of up to 78% in the near-infrared region, leading to an overall conversion efficiency of 24%. Moreover, the new hybrid perovskite photovoltaic cells demonstrated high stability, maintaining over 80% of their initial efficiency after 800 hours of illumination, even under extreme humidity conditions.
“Through this study, we effectively resolved the issues of charge accumulation and energy band mismatch faced by current hybrid perovskite/organic solar cells,” explained Professor Jung-Yong Lee of the School of Electrical Engineering (KAIST). “We can now significantly enhance power conversion efficiency while maximizing near-infrared light capture performance, marking a new milestone that addresses the mechanical-chemical stability issues of existing perovskites and overcomes optical limitations.”
The research has been published in the journal Advanced Materials.
