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Quantum dot (QD)-based luminescent down-shifting (LDS) layers were deposited on Cu2ZnSn(S,Se)4 (CZTSSe) solar cells via the drop-casting method. The LDS layers can easily widen the narrow absorption wavelength regions of single-junction solar cells and enable improvement of the short-circuit current. The optical properties of LDS layers deposited on glass and containing different QD contents were analyzed based on their transmittance, reflectance, and absorbance. The absorber films to be used in the CZTSSe solar cells were determined by X-ray diffraction measurements and Raman spectroscopy to determine their crystal structures and secondary phases, respectively. The completed CZTSSe solar cells with LDS layers showed increased ultraviolet responses of up to 25% because of wavelength conversion by the QDs. In addition, the impact of the capping layer, which was formed to protect the QDs from oxygen and moisture, on the solar cell performance was analyzed. Thus, a maximal conversion efficiency of 7.3% was achieved with the 1.0 mL QD condition; furthermore, to the best of our knowledge, this is the first time that LDS layers have been experimentally demonstrated for CZTSSe solar cells.

We attempted to grow (10–13) semi-polar GaN on graphene to confirm the possibility of a remote epitaxy of semi-polar GaN. Single crystalline (10–13) GaN was obtained on an optimized template using optimized growth conditions. However, (10–13), (0002), and other GaN orientations were found under the same growth conditions on a graphene-coated template. Scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy revealed that multi-domain GaN and (0002) GaN occurred in areas with a damaged graphene interfacial layer and intact graphene, respectively. Raman spectroscopy confirmed that graphene could survive under the growth conditions used here. Using cross-sectional scanning electron microscopy, we propose a simple approach to distinguish damaged graphene. Although the remote epitaxy of semi-polar GaN has not been demonstrated despite the usage of an optimized template and growth conditions, our results confirm the importance of the interfacial state in determining the crystallinity of the overgrown layer. [ABSTRACT FROM AUTHOR]

Gallium Nitride: Influence of Temperature-Dependent Substrate Decomposition on Graphene for Separable GaN Growth (Adv. Keywords: gallium nitride; graphene; MOCVD; substrate decomposition Gallium nitride, graphene, MOCVD, substrate decomposition. [Extracted from the article]

In this study, we integrated RGB inorganic LEDs onto a sapphire substrate. Blue and green subpixels were monolithically integrated using a selective area growth method, while red subpixels were formed by adhesive bonding and epitaxial lift‐off. The fabricated RGB subpixels could be independently controlled to realize the full color spectrum. [ABSTRACT FROM AUTHOR]

Quantum dot (QD)-based luminescent down-shifting (LDS) layers were deposited on Cu2ZnSn(S,Se)4 (CZTSSe) solar cells via the drop-casting method. The LDS layers can easily widen the narrow absorption wavelength regions of single-junction solar cells and enable improvement of the short-circuit current. The optical properties of LDS layers deposited on glass and containing different QD contents were analyzed based on their transmittance, reflectance, and absorbance. The absorber films to be used in the CZTSSe solar cells were determined by X-ray diffraction measurements and Raman spectroscopy to determine their crystal structures and secondary phases, respectively. The completed CZTSSe solar cells with LDS layers showed increased ultraviolet responses of up to 25% because of wavelength conversion by the QDs. In addition, the impact of the capping layer, which was formed to protect the QDs from oxygen and moisture, on the solar cell performance was analyzed. Thus, a maximal conversion efficiency of 7.3% was achieved with the 1.0 mL QD condition; furthermore, to the best of our knowledge, this is the first time that LDS layers have been experimentally demonstrated for CZTSSe solar cells. [ABSTRACT FROM AUTHOR]

Graphene has been adopted in III−V material growth since it can reduce the threading dislocations and the III−V epilayer can easily be separated from the substrate due to the weak chemical bond. However, depending on the substrate supporting the graphene, some substrates decompose in the III−V material growth environment, which results in the problem that no graphene remains. In this study, the influence of temperature‐dependent substrate decomposition on graphene through an annealing process that resembles conventional growth conditions in metal–organic chemical vapor deposition (MOCVD) is investigated. It is also confirmed that trimethylgallium, hydrogen, and ammonia gases do not directly affect the graphene loss through gallium nitride (GaN) growth on a graphene/sapphire. In addition, GaN grown on graphene/sapphire could separate, but GaN grown on a graphene/GaN template could not be separated due to GaN template decomposition and related graphene damage. Through further investigation for graphene/gallium arsenide, it is deduced that the gallium generated by substrate decomposition does not play a major role in damage to the graphene but instead the nitrogen generated by substrate decomposition is closely related to it. These results suggest that it is very important to adopt a decomposition‐free substrate that do not damage graphene during GaN growth in MOCVD. [ABSTRACT FROM AUTHOR]