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Abstract We demonstrate shear‐printed layered photonic films with vivid structural coloration from bio‐derived cellulose nanocrystals and highly aligned Ti3C2TxMXene nanoflakes. These ultrathin films (700–1500 nm) show high light transmittance above 40% in the visible range. In reflectance mode, however, the films appear vividly colored and iridescent due to the multiple distinct photonic bandgaps in the visible and near‐infrared ranges, which are rarely observed in CNC composites. The structural coloration is controlled by the stacking of MXene nanoscale‐thin layers separated by the thicker cellulose nanocrystals matrix, as confirmed by photonic simulations. The unique combination of distinctly different optical appearances in transmittance and reflectance modes occurs in films printed with just a few layers. This is because of the molecularly smooth interfaces and the high refractive contrast between bio‐based and inorganic phases, which result in a concurrence of constructive and destructive interference. These lamellar biophotonic films open the possibilities for advanced radiative cooling, camouflaging, multifunctional capacitors, and optical filtration applications, while the cellulose nanocrystals matrix strengthens their flexibility, robustness, and facilitates sustainability.
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Exploring the Impact of Spatial Factors on Circadian Daylight Distribution
Lighting strongly influences indoor well-being, yet existing metrics like "Daylight Autonomy" and "Annual Solar Exposure" overlook circadian light. Research highlights circadian light's significant impact on human performance, creating a need to explore spatial factors affecting its distribution. This study examines the influence of surface reflectance, proximity to windows, windows' optical properties, and gaze direction on circadian light. Using the Lark Plugin for Grasshopper, simulations were conducted in a box-model room with ten glazing systems varying in visible transmittance. The results show that windows with a visible transmittance below 0.3 fail to provide adequate circadian light unless the gaze is perpendicular. Among surface reflectance factors, wall reflectance proved more critical than ceiling reflectance in optimizing circadian light exposure.
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- Award ID(s):
- 2001207
- PAR ID:
- 10572082
- Publisher / Repository:
- American Solar Energy Society
- Date Published:
- ISBN:
- 979-8-3313-0908-4
- Page Range / eLocation ID:
- 167 to 178
- Subject(s) / Keyword(s):
- circadian light spatial factors window wellbeing daylight
- Format(s):
- Medium: X
- Location:
- Washington DC, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.52202/077496-0015
