Nanotechnologies / Materials
Green device, Sustainable electronics

Wood-derived semiconducting nanomaterials
with customizable 3D structures and functions
Department of Functionalized Natural Materials, SANKEN (The Institute of Scientific and Industrial Research)
Associate Professor Hirotaka Koga
https://researchmap.jp/hkoga?lang=en

Nanotechnologies / Materials

Abstract
Semiconductor nanomaterials with 3D network structures haveunique properties such as large specific surface area, high permeability, and electrical conductivity that make them suitable foradsorption, separation, and sensing applications. However, conventional semiconductor nanomaterials are limited in the designability of their 3D structures and the tuning range of their electricalproperties, which greatly restricts their actual functions and applications.
In this context, we have developed a new technology for designing 3D structures and tuning electrical properties by stepwise
carbonization using “nanopaper,” a paper derived from wood cellulose nanofibers. The as-developed “nanopaper semiconductor”
enables 3D structure design at the nano- to micro- to macro-scaleand systematic control of electrical properties at the insulator toquasi-conductor level (Figure 1). These features outperform conventional semiconductor nanomaterials and enable customizationof 3D structures and functions according to purpose and application. In actual, they have demonstrated excellent performances ina wide range of applications, from sensor devices to energy generation devices (Figure 2).

▍ Significance of the research and Future perspective
This research will create new value for wood-derived cellulose
nanofibers as semiconductors, and further development of theirfunctions and applications is expected. In the future, this finding
will contribute to the realization of sustainable electronics derived
from biological resources that do not depend on metals or petroleum resources.

▍ Background & Results
Nano- to micro- to macro-scale 3D structure design and electrical property tuning are rational strategies to control functions andapplications of semiconductor nanomaterials. However, conventional semiconductor nanomaterials and technologies have limited
the scope of 3D structure design and tuning of electrical properties. In other words, the nano-micro-macro trans-scale 3D structure
design and wide tuning of electrical properties have not yet beenachieved by a single semiconductor nanomaterial.
In this study, we have developed semiconductor nanomaterials
with widely and systematically tunable electrical properties by
stepwise carbonization of “nanopaper” derived from wood cellulose nanofibers. The tunable range of electrical properties of this13-2“nanopaper semiconductor” covers electrical resistivity: 10 to 10
Ω cm (insulator to quasi-conductor) (Figure 1a), carrier type: p- or
n-type, and carrier mobility: 0.235 to 2.59 cm2 V-1 s-1. Furthermore,
by applying the paper-specific structural design techniques (spatially-controlled drying, embossing, origami, and kirigami), we haveachieved controlling 3D structure of the nanopaper semiconductor at the trans-scale from nano- to micro- to macro-scale (Figure1b). Both the wide tunability of electrical properties and nano-micro-macro trans-scale designability of 3D structures are notablefeatures of the nanopaper semiconductor that are better thanthose of previously reported 3D semiconductor structures. Thesefeatures enable customization of function and structure of the nanopaper semiconductor, according to purpose and application. In
actual, the nanopaper semiconductor provided not only the tunable functionality for applications ranging from water-vapor-selectivesensors (Figure 2a) to biofuel cell electrodes for energy generation(Figure 2b), but also the designability of macroscopic device configurations for stretchable and wearable applications.

Figure 1(cc BY, credit: 2022 Koga et al. Nanocellulose paper semiconductor with a 3D
network structure and its nano−micro−macro trans-scale design. ACS Nano)

Figure 2(cc BY, credit: 2022 Koga et al. Nanocellulose paper semiconductor with a 3D
network structure and its nano−micro−macro trans-scale design. ACS Nano)

P a t e n t
Tr e a t i s e

Koga, Hirotaka; Nagashima, Kazuki; Suematsu, Koichi et al. Nanocellulose paper semiconductor with a 3D network structure and its nano–micro–macrotrans-scale design. ACS Nano. 2022, 16 (6), 8630-8640. doi: 10.1021/acsnano.1c10728

URL
K e y w o r d nanocellulose, semiconductor, sensor device, energy generation device