2018 Fiscal Year Annual Research Report
欠陥フリー低鉛ペロブスカイトナノ結晶の基礎研究と光電デバイスへの応用
| Project/Area Number |
18F18370
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
沈 青 電気通信大学, 大学院情報理工学研究科, 教授 (50282926)
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| Co-Investigator(Kenkyū-buntansha) |
LIU FENG 電気通信大学, 大学院情報理工学研究科, 外国人特別研究員
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| Project Period (FY) |
2018-11-09 – 2021-03-31
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| Keywords | perovskite nanocrystals / perovskite solar cell / near-unity PL QY |
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| Outline of Annual Research Achievements |
Trioctylphosphine (TOP)-based syntheses of CsPbI3 perovskite quantum dots (QDs) yield unprecedented high photoluminescence quantum yield (PLQY) of 100%, lower stokes shifts, and longer carrier lifetimes due to their enhanced crystallinity. This synthetic route relies on a heavily Pb-rich condition or a large Pb:Cs molar ratio in precursor solution to produce QDs with appropriate stoichiometry as well as to guarantee a good colloidal stability. The high Pb condition is achieved by a high concentration of PbI2 prepared in TOP. Here we find such Pb-rich strategies can be avoided by providing additional iodine ions using other metal halide salts. In particular GeI2, which contrary to PbI2, readily dissolves in TOP. CsPbI3 QDs prepared using PbI2/GeI2 combination show near-unity PL QY and improved chemical stability compared to the previous synthetic route. Furthermore we find no sign of Ge incorporation in the QDs (compositionally or energetically). The ensuing QD solar cells deliver power conversion efficiency of 12.15% and retain 85% of its peak performance after storage over 90 days. The PbI2/GeI2 dual-source iodine synthetic approach presented here represents a more rational and robust route to high-quality CsPbI3 QDs.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The proposed study has been finished.
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| Strategy for Future Research Activity |
Alloyed Sn-Pb halide perovskites hold great potential for near-infrared applications due to their narrow band gaps and lower toxicity. However, Sn vacancy defect can be facilely generated due to its low formation energy, causing detrimental effects for the carrier transport and device efficiency. The plan of this study is to decrease Sn vacancies by doping strategy, which introduces impurities that can strongly modify optoelectronic properties of the materials.
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