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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits

Professor

Portrait of Tönu Pullerits; Photo: Kennet Ruona

Optimizing the quasi-equilibrium state of hot carriers in all-inorganic lead halide perovskite nanocrystals through Mn doping : fundamental dynamics and device perspectives

Author

  • Jie Meng
  • Zhenyun Lan
  • Weihua Lin
  • Mingli Liang
  • Xianshao Zou
  • Qian Zhao
  • Huifang Geng
  • Ivano E. Castelli
  • Sophie E. Canton
  • Tönu Pullerits
  • Kaibo Zheng

Summary, in English

Hot carrier (HC) cooling accounts for the significant energy loss in lead halide perovskite (LHP) solar cells. Here, we study HC relaxation dynamics in Mn-doped LHP CsPbI3 nanocrystals (NCs), combining transient absorption spectroscopy and density functional theory (DFT) calculations. We demonstrate that Mn2+ doping (1) enlarges the longitudinal optical (LO)-acoustic phonon bandgap, (2) enhances the electron-LO phonon coupling strength, and (3) adds HC relaxation pathways via Mn orbitals within the bands. The spectroscopic study shows that the HC cooling process is decelerated after doping under band-edge excitation due to the dominant phonon bandgap enlargement. When the excitation photon energy is larger than the optical bandgap and the Mn2+ transition gap, the doping accelerates the cooling rate owing to the dominant effect of enhanced carrier-phonon coupling and relaxation pathways. We demonstrate that such a phenomenon is optimal for the application of hot carrier solar cells. The enhanced electron-LO phonon coupling and accelerated cooling of high-temperature hot carriers efficiently establish a high-temperature thermal quasi-equilibrium where the excessive energy of the hot carriers is transferred to heat the cold carriers. On the other hand, the enlarged phononic band-gap prevents further cooling of such a quasi-equilibrium, which facilitates the energy conversion process. Our results manifest a straightforward methodology to optimize the HC dynamics for hot carrier solar cells by element doping. This journal is

Department/s

  • Chemical Physics
  • NanoLund: Center for Nanoscience
  • eSSENCE: The e-Science Collaboration

Publishing year

2022-02-14

Language

English

Pages

1734-1745

Publication/Series

Chemical Science

Volume

13

Issue

6

Document type

Journal article

Publisher

Royal Society of Chemistry

Topic

  • Condensed Matter Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 2041-6520