Efficient luminescent solar concentrators based on self-absorption free, Tm2+ doped halides

The optical and luminescence properties of CaI2 and NaCl doped with divalent thulium are reported for solar energy applications. These halides strongly absorb solar light from the UV up to 900 nm due to the intense Tm2+ 4f13→4f125d1 electronic transitions. Absorption is followed by emission of 1140 nm light due to the 2F5/2→2F7/2 transition of the 4f13 configuration that can be efficiently converted to electric power by thin film CuInSe2 (CIS) solar cells. Because of a negligible spectral overlap between absorption and emission spectra, a luminescent solar concentrator (LSC) based on these black luminescent materials would not suffer from self-absorption losses. The Tm2+ doped halides may therefore lead to efficient semi-transparent power generating windows that absorb solar light over the whole visible spectrum. It will be shown that the power efficiency of the Tm2+ based LSCs can be up to four times higher compared to LSCs based on organic dyes or quantum dots.

Expanded Clinical Spectrum of Multiple Evanescent White Dot Syndrome with Multimodal Imaging

PURPOSE: To evaluate and characterize multiple evanescent white dot syndrome abnormalities with modern multimodal imaging modalities. METHODS: This retrospective cohort study evaluated fundus photography, fluorescein angiography, indocyanine green angiography, optical coherence tomography, enhanced depth imaging optical coherence tomography, short-wavelength autofluorescence, and near-infrared autofluorescence. RESULTS: Thirty-four multiple evanescent white dot syndrome patients with mean age of 28.7 years were studied (range, 14-49 years). Twenty-six patients were women, and eight were men. Initial mean visual acuity was 0.41 logMAR. Final mean visual acuity was 0.03 logMAR. Fluorescein angiography shows a variable number of mid retinal early fluorescent dots distributed in a wreathlike pattern, which correlate to fundus photography, fundus autofluorescence, and indocyanine green angiography. Indocyanine green angiography imaging shows the dots and also hypofluorescent, deeper, and larger spots, which are occasionally confluent, demonstrating a large plaque of deep retinal hypofluorescence. Optical coherence tomography imaging shows multifocal debris centered at and around the ellipsoid layer, corresponding to the location of spots seen with photography, indocyanine green angiography, and fluorescein angiography. Protrusions of the hyperreflectant material from the ellipsoid layer toward the outer nuclear layer correspond to the location of dots seen with photography, indocyanine green angiography, and fluorescein angiography. CONCLUSION: Multimodal imaging analysis of the retina in patients with multiple evanescent white dot syndrome shows additional features that may help in the diagnosis of the disease and in further understanding its etiology. Multiple evanescent white dot syndrome is predominantly a disease of the outer retina, centered at the ellipsoid zone, but also involving the interdigitation zone and the outer nuclear layer.