| 研究実績の概要 |
The target of this project is to develop efficient and stable CsPbX3 perovskite solar cells. In 2021, the following results have been achieved.
A molecule passivation engineering was developed to suppress the perovskite surface defects. As a result, the Voc of CsPbI2.25Br0.75 (1.86 eV) solar cells was improved from 1.36 to 1.43 V, reaching 92% of the Shockley-Queisser limit, which is the highest value among all ever-reported CsPbX3 solar cells. Meanwhile, it promoted the Voc of CsPbI1.5Br1.5 (1.99 eV) cells to 1.51 V (90% of the limit) and that of CsPbIBr2 (2.10 eV) cells to 1.54 V (87% of the limit), implying its universality. This method solved the problem of severe Voc loss in CsPbX3 cells and makes their applications to tandem solar cells and indoor photovoltaics more promising.
BiOI layer on the CsPbI2Br film was made by spin-coating a BiI3 solution followed by an annealing process. Results show that with low concentration (0.03-0.1 mg/ml), the device performance slightly increased, proving the positive role of BiOI (or BiI3). While further increasing the concentration to 0.3-0.9 mg/ml, the performance, mainly the FF sharply decreased, which indicates that too thick BiOI (or BiI3) would hinder the charge transfer. This work proves the possibility of constructing a BiOX (X=I, F, Cl, Br) ultra-thin layer on CsPbX3 perovskite for developing efficient and stable solar cells.
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