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Korean scientists have fabricated an organic perovskite solar cell with a uniform subnanometer dipolar layer. The device recorded a power conversion efficiency of 24% during testing, a new record for lead-based perovskite-organic hybrid solar cells.
Researchers at the Korea Advanced Institute of Science and Technology (KAIST) and Yonsei University have fabricated a highly efficient and stable organic-inorganic hybrid solar cell.
In the article “ Suppressing Hole Accumulation Through Sub-Nanometer Dipole Interfaces in Hybrid Perovskite/Organic Solar Cells for Boosting Near-Infrared Photon Harvesting” published in the journal Advanced Materials , it is noted that a key obstacle to improving the efficiency of perovskite-organic hybrid solar cells is the energy level mismatch at the perovskite/bulk-heterojunction (BHJ) interface, which leads to charge accumulation.
The article adds that current lead-based perovskite solar cells cannot utilize about 52% of the total solar energy because their absorption spectrum is limited to the visible light region with a wavelength of 850 nm or less.
To solve the problem, the team of researchers designed a hybrid device that combined a bulk organic heterojunction (BHJ) with perovskite, resulting in a solar cell that can absorb into the near-infrared region.
The researchers introduced a subnanometer dipolar interface layer, based on an isomer known as B3PyMPM, directly onto the perovskite surface, which supposedly alleviated the energy barrier between the perovskite and the BHJ. This was found to suppress charge accumulation, maximize the near-infrared contribution, and enhance the current density to 4.9 mA/cm².The cell was constructed with an indium tin oxide (ITO) substrate, a self-assembled monolayer based on MeO-2PACz, the perovskite absorber, the dipolar interfacial layer, the BHJ interface, a bathocuproine (BCP) buffer layer, and a copper (Cu) metal contact.
In tests, the hybrid device achieved a power conversion efficiency of 24%, up from 20.4%, which the research paper says is a record for lead-based perovskite-organic hybrid solar cells.
The device also achieved high internal quantum efficiency (IQE) compared to previous studies, reaching 78% in the near-infrared region. It also demonstrated high stability, maintaining more than 80% of its initial efficiency after more than 800 hours in extreme humidity conditions.
“With this study, we have effectively solved the charge accumulation and energy band mismatch problems faced by existing hybrid organic perovskite solar cells, and will be able to significantly improve the power conversion efficiency while maximizing the light-harvesting performance in the near-infrared,” said Jung-Yong Lee, one of the authors of the study. “It will be a new breakthrough that can solve the mechanical-chemical stability problems of existing perovskites and overcome optical limitations.” |
