Traditional lead-based perovskite solar cells are limited by their absorption spectrum, which is confined to visible light with wavelengths up to 850 nanometers. This constraint prevents them from utilizing approximately 52% of total solar energy. The new hybrid design developed by the KAIST team integrates an organic bulk heterojunction (BHJ) with perovskite, expanding absorption capabilities into the near-infrared range.
A major advancement in this technology is the introduction of a sub-nanometer dipole layer. This thin layer effectively reduces the energy barrier between the perovskite and the organic BHJ, alleviating issues such as charge accumulation.
This enhancement maximizes the near-infrared contribution and raises the current density (JSC) to 4.9 mA/cm. Consequently, the power conversion efficiency (PCE) of this hybrid solar cell has increased from 20.4% to 24.0%. The research also recorded a high internal quantum efficiency (IQE) of 78% in the near-infrared region, a significant achievement compared to previous studies.
The stability of the device is another highlight, maintaining more than 80% of its initial efficiency under extreme humidity for over 800 hours. "Through this study, we have effectively solved the charge accumulation and energy band mismatch problems faced by existing perovskite/organic hybrid solar cells," said Professor Jung-Yong Lee. "This advancement improves power conversion efficiency and mechanical-chemical stability, overcoming optical limitations."
The research was led by Ph.D. candidate Min-Ho Lee and Master's candidate Min Seok Kim as co-first authors and was published in the September 30th online edition of 'Advanced Materials'.
Related Links
KAIST Advanced Devices for Energy Conversion
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