Local Observation of Phase Segregation in Mixed-Halide Perovskite.

Tang X, van den Berg M, Gu E, Horneber A, Matt G, Osvet A, Meixner AJ, Zhang D, Brabec C (2018)

Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2018

Journal

Nano Letters American Chemical Society

Book Volume: 18

Pages Range: 2172-2178

Journal Issue: 3

URI: https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.8b00505

DOI: 10.1021/acs.nanolett.8b00505

Abstract

Mixed-halide perovskites have emerged as promising materials for optoelectronics due to their tunable bandgap in the entire visible region. A challenge remains however in the photo-induced phase-segregation, narrowing the bandgap of mixedhalide perovskites under illumination thus restricting applications. Here we use a combination of spatially-resolved and bulk measurements to give an in-depth insight into this important yet unclear phenomenon. We demonstrate that photo-induced phase-segregation in mixed-halide perovskites selectively occurs at the grain boundaries rather than within the grain centers by using shear-force scanning probe microscopy in combination with confocal optical spectroscopy. Such difference is further evidenced by light-biased bulk Fourier-transform photocurrent spectroscopy,
which shows the iodine-rich domain as a minority phase coexisting with the homogenously mixed phase during illumination. By mapping the surface potential of mixed-halide perovskites, we evidence the higher concentration of positive space charge near grain boundary possibly provides the initial driving force for phasesegregation, while entropic mixing dominates the reverse process. Our work offers detailed insight into the microscopic processes occurring at the boundary of crystalline perovskite grains and will support the development of better passivation strategies, ultimately allowing to process environmentally more stable perovskite films.

Authors with CRIS profile

Xiaofeng Tang Institute Materials for Electronics and Energy Technology (i-MEET) Ening Gu Institute Materials for Electronics and Energy Technology (i-MEET) Gebhard Matt Institute Materials for Electronics and Energy Technology (i-MEET) Andres Osvet Institute Materials for Electronics and Energy Technology (i-MEET) Christoph Brabec Institute Materials for Electronics and Energy Technology (i-MEET)

Involved external institutions

Eberhard Karls Universität Tübingen DE Germany (DE)

How to cite

APA:

Tang, X., van den Berg, M., Gu, E., Horneber, A., Matt, G., Osvet, A.,... Brabec, C. (2018). Local Observation of Phase Segregation in Mixed-Halide Perovskite. Nano Letters, 18(3), 2172-2178. https://dx.doi.org/10.1021/acs.nanolett.8b00505

MLA:

Tang, Xiaofeng, et al. "Local Observation of Phase Segregation in Mixed-Halide Perovskite." Nano Letters 18.3 (2018): 2172-2178.

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