Regensburg 2022 – wissenschaftliches Programm

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SYSD: SKM Dissertation Prize 2022

SYSD 1: SKM Dissertation Prize

SYSD 1.1: Hauptvortrag

Montag, 5. September 2022, 10:15–10:45, H2

Charge localisation in halide perovskites from bulk to nano for efficient optoelectronic applications — •Sascha Feldmann — Cavendish Laboratory, University of Cambridge, Cambridge, UK — Rowland Institute, Harvard University, Cambridge, USA

Halide perovskites have emerged as high-performance semiconductors for efficient optoelectronic devices like solar cells or LEDs. Yet, we still do not fully understand why these materials work so efficiently, given that we can process them crudely from solution, likely introducing many defects detrimental to devices based on conventional crystalline semiconductors like silicon. In this talk, I will give an overview of our recent work on understanding the high luminescence yields observed in i) bulk mixed-halide thin films and ii) atomically doped nanocrystals. We show that spatially varying energetic disorder in the electronic states of mixed-halide films causes local charge accumulation, which unearths a strategy for efficient charge extraction at low-light conditions for solar cells and for efficient light emission in LEDs operating at low currents. In doped perovskite nanocrystals, we find that the dopant-induced lattice periodicity breaking results in the transient localisation of charges with an increased overlap of electron and hole wavefunctions. This leads to increased radiative rates - a property that is typically intrinsic to a semiconductor and hard to change - together with reduced non-radiative losses, paving the way to highly efficient LEDs and quantum applications. Overall, these findings hint at energetic disorder in these materials not only being tolerated but potentially helpful in explaining their high performance.