Benefits from disorder?! How local bandgap modulation in halide perovskites can boost optoelectronic performance
Sascha Feldmann a
a Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, United Kingdom
Materials for Sustainable Development Conference (MATSUS)
Proceedings of nanoGe Fall Meeting 2021 (NFM21)
#SPMEn21. Visualising nanoscale phenomena in functional materials
Online, Spain, 2021 October 18th - 22nd
Organizers: Stefan Weber, Brian Rodriguez and Juliane Borchert
Invited Speaker, Sascha Feldmann, presentation 039
DOI: https://doi.org/10.29363/nanoge.nfm.2021.039
Publication date: 23rd September 2021

Halide perovskites have emerged as high-performance semiconductors for efficient optoelectronic devices, not least because of their bandgap tunability using mixtures of different halide ions. In this talk, I will give an overview of our recent work on understanding why these materials show such unexpectedly high photoluminescence (PL) yields.

We show that spatially varying energetic disorder in the electronic states of such mixed-halide films causes local charge accumulation, creating photodoped regions, which unearths a strategy for efficient light emission at low charge-injection in solar cells and light-emitting diodes [1].

Combining temperature-dependent PL microscopy with computational modelling we quantify the impact of local bandgap variations from disordered halide distributions on the global PL yield in mixed-halide perovskite films [2]. We find that fabrication temperature, surface energy, and charge recombination constants are key for describing local bandgap variations and charge carrier funneling processes that control the PL quantum efficiency. Finally, we show that further luminescence efficiency gains are possible through tailored bandgap modulation in the future, even for materials that have already demonstrated high luminescence yields.

[1] Feldmann et al., Nature Photonics 14, 123 (2020).

[2] Feldmann et al., Advanced Optical Materials 18, 2100635 (2021).

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