Less Defect and Stable Perovskite Nanocrystals: Optical Property and Photoexcited Carrier Dynamics

Perovskite nanocrystlas (PNCs) have gained significant attention for both fundamental research and applications of optoelectronic devices owing to their appealing optoelectronic properties and excellent chemical processability. For their wide range of potential applications, synthesizing PNCs with high crystal quality and stability is of crucial importance. Recently, we have suceeded in synthesis of phase stable and less defect PNCs, including APbX₃ NCs (A: FA, MA, Cs; X: I, Br, Cl), Sn-Pb alloyed NCs and Sn-based PNCs [1-7]. We have demonstrated that a high room-temperature photoluminescence quantum yield (PL QY) of close to 100% can be obtained in the Pb-based PNCs, signifying the achievement of ignorable less trapping defects in the PNCs. Ultrafast kinetic analysis with time-resolved transient absorption spectroscopy evidences the negligible electron or hole trapping pathways in our PNCs, which explains such a high quantum efficiency. In addtion, photoexcited hot and cold carrier dynamics as well as charge transfer were systematically investigated [4,8,9]. Solar cells based on these high-quality PNCs exhibit power conversion efficiency of over 15%, showing great promise for practical application. In addition, through metal doping and Sn (IV) control [5-7,10] , we found that Sn(IV)-induced defects and distortions could be reduced greatly in Sn and Sn-Pb PNCs. As a result, stable Sn and Sn-Pb PNCs with ultra long carrier lifetimes (&gt; 180 ns) were realized. Our findings provide new insights into the materials design strategies for improved optoelectronic properties of Sn-containing perovskites [10].<br/><br/><br/><b>References</b><br/>1. F. Liu and Q. Shen et al.<i>, </i>ACS Nano 11 (2017) 10373<br/>2. F. Liu and Q. Shen et al., J. Am. Chem. Soc. (2017), 139, 16708.<br/>3. F. Liu and Q. Shen et al., Chem. Mater. 32 (2020) 1089.<br/>4. C. Ding and Q. Shen et al., Nano Energy 67 (2020) 104267.<br/>5 F. Liu and Q. Shen et al., Angew. Chem. Int. Ed. 59 (2020) 8421.<br/>6. J. Jiang, F. Liu, Q. Shen and SX. Tao, J. Mater. Chem. A 9 (2021) 12087.<br/>7. F. Liu and Q. Shen et al., ACS Appl. Nano Mater. 4 (2021) 3958.<br/>8. Hua Li and Q. Shen et al., Adv. Mater. 35 (2023) 2301834.<br/>9. Yusheng Li and Q. Shen et al., arXiv preprint arXiv:2209.02202.<br/>10. Yusheng Li and Q. Shen et al., submitted.