Origin of Long Lifetime of Band-Edge Charge Carriers in Solar Cell Perovskites

• Speaker: Prof. Seung-Hun Lee (University of Virginia)
• Date: Monday, December 18, 2017, at 17:00
• Place: Jungho Seminar

Long carrier lifetime is what makes hybrid organic-inorganic perovskites high performance photovoltaic materials. Lee group and his colleagues showed [1-3] that the screening of band-edge charge carriers by rotation of organic cation molecules is a major contribution to the prolonged carrier lifetime. Their results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photo-excited electrons and holes is suppressed by the screening, leading to extend the lifetime. Thus, searching for organic-inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.

• Reference

[1] Origin of Long Lifetime of Band-Edge Charge Carriers in Organic-Inorganic Lead Iodide Perovskites, Tianran Chen et al., Proceedings of National Academy of Sciences 114, 7519-7524, (2017).

[2] Entropy Driven Structural Transition and Kinetic Trapping in Formamidinium Lead Iodide Perovskite, Tianran Chen et al., Science Advances 2, e1601650 (2016).

[3] Rotational dynamics of organic cations in CH3NH3PbI3, T. Chen et al., Phys. Chem. Chem. Phys. 17, 31278-31286 (2015).

 This talk was canceled.