Scanning x-ray excited optical luminescence of heterogeneity in halide perovskite alloys

Abstract

Understanding the optoelectronic properties of optically active materials at the nanoscale often proves challenging due to the diffraction-limited resolution of visible light probes and the dose sensitivity of many optically active materials to high-energy electron probes. In this study, we demonstrate correlative synchrotron-based scanning X-ray Excited Optical Luminescence (XEOL) and X-ray Fluorescence (XRF) to simultaneously probe local composition and optoelectronic properties of halide perovskite thin films of interest for photovoltaic and optoelectronic devices. We find that perovskite XEOL stability, emission redshifting, and peak broadening under hard X-ray irradiation correlates with trends seen in photoluminescence measurements under continuous visible light laser irradiation. The XEOL stability is sufficient under the intense X-ray probe irradiation to permit proof-of-concept correlative mapping. Typical synchrotron X-ray fluorescence and nano-diffraction measurements use acquisition times 10-100x shorter than the 5-second acquisition employed for XEOL scans in this study, suggesting that improving luminescence detection should allow correlative XEOL measurements to be performed successfully with minimal material degradation. Analysis of the XEOL emission from the quartz substrate beneath the perovskite reveals its promise for use as a real-time in-situ X-ray dosimeter, which could provide quantitative metrics for future optimization of XEOL data collection for perovskites and other beam-sensitive materials. Overall, the data suggest that XEOL represents a promising route towards improved resolution in the characterization of nanoscale heterogeneities and defects in optically active materials that may be implemented into X-ray nanoprobes to complement existing X-ray modalities.

The future of self-driving laboratories: from human in the loop interactive AI to gamification

“…3, the emerging paradigm in materials discovery is to achieve a fully automated workflow, or “closing the loop”, by seamlessly integrating all stages from materials synthesis and characterization to data analysis and decision-making into a continuous, computer-controlled feedback loop with advanced automation. 54,90 Some proof-of-concept SDLs demonstrated by different laboratories around the world are the Hitosugi–Shimizu lab in Japan, 91 Cronin 92 and Cooper 93,94 labs in the United Kingdom, Swiss CAT+ in Switzerland, 95 Ada 96 in Canada, and the Hippalgaonkar 97 lab in Singapore, as well as the A-Lab, 98,102 Abolhasani, 37 Ahmadi, 100 Buonassisi, 90 Fenning, 101 Amassian, 98,99 Brown, 73 and Coley 75 labs in the United States. These labs showcase the integration of robotics, AI, and machine learning in materials science to automate and optimize the process of materials synthesis, property evaluation, and discovery.…”

Investigation of TM (TM=Mg, Cu) doping effect on the luminescence performance of CsPbCl3 from a first-principles investigation

“…Blue light-emitting devices are key in optoelectronic applications, including wide-gamut, full-color displays, fluorescence-based chemical and biological sensors, and optical detectors [1,2]. In the past few decades, allinorganic CsPbX 3 (X=Cl, Br, I) perovskite has been studied and employed as energy-efficient optoelectronic devices for lighting and displays, owing to the tunable band gap, narrow emission line width, and high photoluminescence quantum yield (PLQY) [3][4][5]. Despite these great advances, CsPbX 3 exhibits lower PLQY of the blue-emitting (380 nm ∼ 500 nm) compared with that of their red and green-emitting counterparts [6][7][8].…”

Unraveling device evolution through multimodal in situ x-ray characterizations in halide perovskite photovoltaics

“…Multimodal X-ray microscopy techniques have proven invaluable as tools for conducting quantitative nanoscale studies owing to their high penetrative power and ability to investigate chemical composition, structural defects, and optoelectronic performance properties within photovoltaic devices [4]. For example, X-ray excited optical luminescence (XEOL) and X-ray fluorescence (XRF) techniques correlate the compositional complexities such as chlorine content on optoelectronic performance in perovskite thin films [5]; XRF and X-ray nanodiffraction (XRD) coupled with electron beam induced current (EBIC) techniques show the negative impact of rubidium aggregation on device performance of halide perovskite solar cells [6]; and hard X-ray photoelectron spectroscopy (HAXPES) and X-ray absorption spectroscopy (XAS) techniques enable depth-resolved measurements of chlorine distribution throughout the perovskite and substrate layers to elucidate its impact on device performance [7].…”