Spatially-Resolved X-Ray Excited Optical Luminescence of Metal Halide Perovskites

X-Ray Excited Optical Luminescence (XEOL) is a photon-in, photon-out technique that enables probing of electronic structure and optoelectronic quality of materials using synchrotron-generated X-rays. Coupled with nanoprobe X-ray microscopy such as X-Ray Fluorescence (XRF), XEOL can provide valuable information in helping draw correlations between local compositional and electronic structure without the need to metallize or complete a device. Using an off-axis parabolic mirror to improve luminescence collection, we demonstrate spatially resolved XEOL using the X-Ray Nanoprobe at Advanced Photon Source Sector 2-ID-D on luminescent halide perovskites. We observe a decay in luminescence intensity after several seconds of continuous X-ray irradiation of hybrid halide perovskites, indicating a degradation of the perovskite over long times relative to typical scanning conditions due to X-ray beam damage, consistent with previous findings in synchrotron nanoprobe diffraction experiments. To optimize for spatially resolved measurements, we evaluate the XEOL signal to noise ratio as a function of of different single point dwell time and point-to-point spacing to achieve a balance of strong luminescence signal and fine spatial resolution. Because of the minimal experimental hardware required, XEOL holds promise to benefit correlative microscopy experiments of halide perovskites and other luminescent materials, offering in situ measurement of the key luminescence optoelectronic figure of merit.