Mesoscopic Materials Research Laboratory Seminar
Supported by “Kobe University Strategic International Collaborative
Research Grant (Type B Fostering Joint Research)”

Date: October 18, 2022, 14:00-15:00
Room: 2E-303 (Meeting Room of Dept. of Electrical and Electronic Engineering)Contact: sugimoto@eedept.kobe-u.ac.jp (Hiroshi Sugimoto)Prof. Ilya Sychugov
KTH Royal Institute of Technology, Dept. of Applied Physics

Transparent Nanocomposites: from Solar Windows to Transparent Wood
Modifications at nanoscale can bring new functionalities to well-established materials, suchas glass and wood. First, fundamental photophysical properties of Si quantum dots (QDs) wereinvestigated on a single-particle level to understand their potential for light conversion1, 2. We
found that Si QDs possess high quantum efficiency and a large Stokes shift, suitable for the roleof nano-phosphors in building-integrated photovoltaics3, 4. As a proof-of-concept we fabricated
20x20 cm2 prototypes, where QD-doped polymer layer is sandwiched between glass plates. Suchsolar windows feature high transparency (>80%), low haze (<3%), high color rendering index (~88) and, at the same time, deliver up to 0.6 W of electrical peak power under one sun5.
Another example of functional transparency achieved by modifications at nanoscale istransparent wood6. We demonstrated that by selectively removing color-containing compound(lignin) from wood fibers, and by filling the lumens with refractive-index-matching polymer,
controlling transparency and haze7. Moreover, adding specific nanoparticles to the cell wall ofsuch a nanocomposite can provide luminescent, photochromic and flame-retardant functions8-10.
These new transparent nanocomposite may broaden the pool of sustainable materials formodern zero- and positive-energy buildings, where traditional glazing and load-bearing
properties can be enhanced with, respectively, photovoltaic and optical functions.
1. Luo, J. W., et al., Absence of Red-shift in the Direct Band Gap of Silicon Nanocrystals with Reduced Size. Nat. Nanotechnol. 2017, 12, 930-932.
2. Zhou, J., et al., Wafer-scale fabrication of isolated luminescent silicon quantum dots using standard CMOS technology. Nanotechnology 2020,31, 505204.
3. Sychugov, I., Analytical Description of a Luminescent Solar Concentrator. Optica 2019, 6, 1046-1049.
4. Zhou, J., et al., Low-Cost Synthesis of Silicon Quantum Dots with Near-unity Internal Quantum Efficiency. J. Phys. Chem. Lett. 2021, 12,8909−8916.
5. Huang, J., et al., Large-area Transparent “Quantum Dots Glass” for Building Integrated Photovoltaics. ACS Photonics 2022, 9, 2499-2509.
6. Höglund, M., et al., Transparent wood biocomposites by fast UV-curing for reduced light-scattering through wood/thiol-ene interface design.
ACS Appl. Mater. Interfaces 2020, 12, 46914.
7. Chen, H., et al., Photon Walk in Transparent Wood: Scattering and Absorption in Hierarchically Structured Materials. Adv. Opt. Mater. 2022,
10, 2102732.
8. Li, Y., et al., Luminescent Transparent Wood. Adv. Opt. Mater. 2017, 5 (1), 1600834.
9. Samanta, A., et al., Reversible dual-stimuli responsive chromic transparent wood bio-composites for smart window applications. ACS Appl.
Mater. Interfaces 2021, 13, 3270-3277.
10. Samanta, A., et al., Charge regulated diffusion of silica nanoparticles into wood for flame retardant transparent wood. Adv. Sustain. Syst.
2022, 6, 2100354.

Program14:00-15:00
Ilya Sychugov, KTH Royal Institute of Technology, Department of Applied Physics“Transparent Nanocomposites: from Solar Windows to Transparent Wood”
15:00-15:15
Hiroshi Sugimoto, Kobe University, Graduate School of Engineering“Optical Functionalities of Colloidal Mie Resonant Silicon Nanoparticles”
15:15-15:30
Hiroaki Hasebe, Kobe University, Graduate School of Engineering“Toroidal Dipole Resonance of Silicon Nanodisk Array for Photochemical Applications”
15:30-15:45
Keisuke Moriasa, Kobe University, Graduate School of Engineering“Narrowband Absorption Enhancement in Silicon Nanodisk Array for NIR
Photodetection”