A density functional theory study on multiple exciton generation in lead chalcogenides |
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Authors: | Nur Farha Shaafi Mohd Fakhrul Zamani Kadir Shujahadeen B Aziz |
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Institution: | 1. Material Technology Programme, Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, Lebuhraya Tun Razak, Gambang, Kuantan, 26300, Pahang, Malaysia;2. Center of Foundation Studies in Science, University of Malaya, 50603 Kuala Lumpur, Malaysia;3. Advanced Polymeric Materials Research Lab, Department of Physics, College of Science, University of Sulaimani, Qylasan Street, Sulaimani, 46001 Kurdistan Regional Government, Iraq;4. Komar Research Center (KRC), Komar University of Science and Technology, Sulaimani, 46001, Kurdistan Regional Government, Iraq |
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Abstract: | AbstractQuantum confined structure-based solar cell is promising two folds increment of the maximum theoretical photovoltaic conversion efficiency i.e., > 60% in comparison with that of the bulk analogs e.g., silicon-based and dye sensitized solar cell (ca. 32% of maximum theoretical efficiency). The key to the significant increment is the ability of the fluorophore to exhibit multiple exciton generation upon absorption photon with sufficient energy. Small size of lead chalcogenides (PbS, PbSe, PbTe) crystals have been reported and proven experimentally could exhibit this unique property. We have investigated few clusters of narrow bandgap lead chalcogenides nanocrystals i.e., (PbS)n, (PbSe)n and (PbTe)n; which n?=?4 - 80. The cluster models were optimized using quantum chemical calculations to the lowest energy geometry at B3LYP/lanl2dz level of theory. The predicted realistic (PbS)80, (PbSe)50, and (PbTe)74 clusters with the size, and bandgap of 4.58?nm (2.00?eV), 4.03?nm (1.51?eV), and 4.84?nm (1.55?eV) are smaller than that of their exciton Bohr radius i.e., 5.01, 13.1, and 24.8?nm respectively. Therefore, the occurrence of multi exciton generation in the clusters is hypothesized upon absorption of photon with Ephoton = 2Eg. |
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Keywords: | Density functional theory lead chalcogenides multiple exciton generation quantum confined structure |
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