New Review : Measuring, controlling and exploiting heterogeneity in optoelectronic nanowires

Interwire and intrawire inhomogeneity

Group PhD students Ruqaiya Al-Abri and Hoyeon Choi have written an invited review article for JPhys Photonics, published today.

Lead author Ruqaiya Al-Abri describes this work:

Among the one-dimensional structures, semiconductor nanowires have attracted great attention; from the growth process to the production of functional devices they have been widely studied. The growth condition of the nanowires can lead to non-uniformity (disorder) in the crystal structure, morphology, and geometry of the nanowire. Consequently, this affects the functionality of individual and/or ensembles of nanowires. However, researchers have benefited from disorder; it has been shown that disorder can enhance the performance of ensemble of nanowires such as in photovoltaic devices. This review article attempts to understand the disorder in these structures, investigates the origin of the inhomogeneity within “interwire” and between “intrawire” nanowires, and outlines different approaches to correlate disorder to functional parameters and hence optimize the performance of the nanowires.

Reference: Measuring, controlling and exploiting heterogeneity in optoelectronic nanowires, Ruqaiya Al-Abri, Hoyeon Choi and Patrick Parkinson, JPhys Photonics, (2021) DOI:10.1088/2515-7647/abe282

New Paper: Visualizing the role of photoinduced ion migration on photoluminescence in halide perovskite grains​

Group student Hoyeon has had a paper accepted in the RSC Journal of Materials Chemistry C, studying the photo-brightening effect in perovskite grains using correlated optical and chemical mapping. In collaboration with the Flavell group and the NanoSIMS group at Manchester, this study linked luminescence lifetime and emission energies to local changes in oxygen and iodine density close to the surface of methyammonium lead iodide grains; a prototypical next-generation photovoltaic material.

This new study unambiguously links the emission efficiency improvement under illumination – the so-called photo-brightening effect – to light-induced migration of iodine into the bulk of the crystal and an increase in oxygen levels close to the surface of the grains. By mapping the emission efficiency and chemical levels on the sub-micron scale, we find that grain size has a decreasing role with light-soaking.

Reference: “Visualizing the role of photoinduced ion migration on photoluminescence in halide perovskite grains​“, J. Mater. Chem. C (2020), DOI:10.1039/d0tc01441a

Conference Proceedings: Spatially and temporally resolved degradation in antisolvent treated perovskite films

Group PhD student Hoyeon Choi has had a conference proceedings accepted for SPIE Europe 2020. As this conference has been cancelled, his talk is available throught the SPIE Digital Form.

In his work, Hoyeon describes the application of confocal and time-resolved spectral mapping to study and understand photobrightening and degradation processes in a prototypical perovskite material fabricated with and without use of anti-solvent treatment.

The presentation and paper are available online now.

Reference: Spatially and temporally resolved degradation in antisolvent treated perovskite films, Hoyeon Choi, Chun-Ren Ke, Stefan Skalsky, Wendy Flavell, and Patrick Parkinson, Proc. SPIE 11365, Organic Electronics and Photonics: Fundamentals and Devices II, 113650Q