Holistic Determination of Optoelectronic Properties using High-Throughput Spectroscopy of Surface-Guided CsPbBr$_3$ Nanowires

Optoelectronic micro- and nanostructures have a vast parameter space to explore for modification and optimisation of their functional performance. This paper reports on a data-led approach using high-throughput single nanostructure spectroscopy to probe > 8,000 structures, allowing for holistic analysis of multiple material and optoelectronic parameters with statistical confidence. The methodology is applied to surface-guided CsPbBr$_3$ nanowires, which have complex and interrelated geometric, structural and electronic properties. Photoluminescence-based measurements, studying both the surface and embedded interfaces, exploits the natural inter-nanowire geometric variation to show that increasing the nanowire width reduces the optical bandgap, increases the recombination rate in the nanowire bulk and reduces the rate at the surface interface. A model of carrier recombination and diffusion is developed which ascribes these trends to carrier density and strain effects at the interfaces and self-consistently retrieves values for carrier mobility, trap densities, bandgap, diffusion length and internal quantum efficiency. The model predicts parameter trends, such as the variation of internal quantum efficiency with width, which is confirmed by experimental verification. As this approach requires minimal a-priori information, it is widely applicable to nano- and micro-scale materials.