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Tönu Pullerits. Portrait.

Tönu Pullerits

Professor

Tönu Pullerits. Portrait.

AI-Enhanced High-Resolution Functional Imaging Reveals Trap States and Charge Carrier Recombination Pathways in Perovskite

Author

  • Qi Shi
  • Tönu Pullerits

Summary, in English

Understanding and managing charge carrier recombination dynamics is crucial for optimizing the performance of metal halide perovskite optoelectronic devices. In this work, we introduce a machine learning-assisted intensity-modulated two-photon photoluminescence microscopy approach for quantitatively mapping recombination processes in MAPbBr3 perovskite microcrystalline films at micrometer-scale resolution. To enhance model accuracy, a balanced classification sampling strategy was applied during the machine learning optimization stage. The trained regression chain model accurately predicts key physical parameters—exciton generation rate ((Formula presented.)), initial trap concentration ((Formula presented.)), and trap energy barrier ((Formula presented.))—across a 576-pixel spatial mapping. These parameters were then used to solve a system of coupled ordinary differential equations, yielding spatially resolved simulations of carrier populations and recombination behaviors at steady-state photoexcitation. The resulting maps reveal pronounced local variations in exciton, electron, hole, and trap populations, as well as photoluminescence and nonradiative losses. Correlation analysis identifies three distinct recombination regimes: 1) a trap-filling regime predominated by nonradiative recombination, 2) a crossover regime, and 3) a band-filling regime with significantly enhanced radiative efficiency. A critical trap density threshold (~1017 (Formula presented.)) marks the transition between these regimes. This work demonstrates machine learning-assisted intensity-modulated two-photon photoluminescence microscopy as a powerful framework for diagnosing carrier dynamics and guiding defect passivation strategies in perovskite materials.

Department/s

  • LTH Profile Area: Photon Science and Technology
  • LTH Profile Area: Nanoscience and Semiconductor Technology
  • NanoLund: Centre for Nanoscience
  • LU Profile Area: Light and Materials
  • Chemical Physics
  • eSSENCE: The e-Science Collaboration

Publishing year

2025-11

Language

English

Publication/Series

Energy and Environmental Materials

Volume

8

Issue

6

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Condensed Matter Physics (including Material Physics, Nano Physics)

Keywords

  • charge carrier dynamics
  • intensity modulation two-photon excited photoluminescence (IM2PM)
  • machine learning
  • nonradiative recombination
  • trap states

Status

Published

ISBN/ISSN/Other

  • ISSN: 2575-0348