Synthesis, Optimization of Cu Nanowires and Application of Its Transparent Electrodes

doi:10.15541/jim20180243

Abstract

Abstract:

As the continuous development of the photovoltaic industry and the flat panel display devices, the demand for transparent electrodes is increasing rapidly. The most commonly used transparent conductive material, ITO, was criticized for its brittleness, which limited its application in the up-and-coming market. Cu nanowire transparent electrodes acts as promising candidate for the new generation of transparent electrodes due to their superior conductivity, low cost, easy accessibility and high flexibility. The synthesis of Cu nanowires and their application in transparent electrodes has drawn lots of attention. Progresses have been made in recent years. A comprehensive elaboration of the controllable synthesis of Cu nanowires through liquid synthesis methods and the mechanism behind them, the fabrication and post-treatment methods of Cu nanowire electrodes, the application of Cu nanowire electrodes in photovoltaic devices, transparent heaters and flexible devices are given. The trends of Cu nanowire electrodes is proposed.

Key words: Cu nanowires, transparent electrodes, controllable synthesis, post-treatment, photovoltaic devices, heaters, flexible and wearable devices, review

CLC Number:

TQ174

WANG Xiao, WANG Ran-Ran, SHI Liang-Jing, SUN Jing. Synthesis, Optimization of Cu Nanowires and Application of Its Transparent Electrodes[J]. Journal of Inorganic Materials, 2019, 34(1): 49-59.

Figures/Tables 8

Fig. 1 Formation of Cu nanowires directed by liquid-crystalline structure of the medium[14]

Table 1 Summary of representitive synthetic methods of Cu nanowires

Solvent	Reducing agent	Capping agent	Cu precursor	Average diameter/nm	Average length	Ref.
DI water	H₃PO₃	Sodium dodecyl benzene sulfonate (SDBS)	CuSO₄·5H₂O,	~85	Tens of micrometers	[17]
DI water	Hydrazine hydrate	Ethylenediamine	Cu(NO₃)₂	35-70	20-80 μm	[11-13, 18]
DI water	Ascorbic Acid	PVP	Cu(NO₃)₂	~50	>10 μm	[19]
DI water	Glucose	HDA	CuCl₂·2H₂O	24±4	Tens to hundreds micrometers	[20]
DI water	Glucose	Oleic acid, Oleylamine	CuCl₂	~45	60-90 μm	[9]
1-hexadecylamine (HDA)	1-Hexadecylamine (HDA)	Hexadecyl trimethyl ammonium bromide (CTAB)	Cu(acac)₂	~78	Tens to hundreds micrometers	[14]
Oleylamine	Oleylamine	Oleylamine	CuCl	~63	10-30 μm	[10]
Oleylamine	Oleylamine	Oleylamine	CuBr₂/CuCl₂	16.2-90.0	20-40 μm	[15-16]
Oleylamine	Tris(trimethylsilyl) silane	Oleylamine	CuCl₂	~16.1	~17 μm	[21]

Fig. 2 SEM images and diameter distribution of Cu nanowires synthesized by using different halide ions[16] (a, e) 2.6 mmol Cl-; (b,f) 2.0 mmol Cl-; (c,g) 1.6 mmol Cl-; (d,h) 1.6 mmol Br-

Fig. 3 (A) SEM image of Cu-Ni NWs with inset showing high resolution SEM image of Cu-Ni NWs; (B) Dark field optical microscopy images of Cu-Ni NWs; (C-H) The distribution of Cu and Ni elements of Cu-Ni NWs with different contents of nickel[23]

Fig. 4 Schematic diagram of the vaccum transfer method (a)[35], the spray-coating method (b)[36], the meyer rod coating method (c)[37], and the roll-to-roll coating method (d)[37]

Fig. 5 (a-c) Schematic diagram of the experimental setup of a typical plasma treatment process; (d) SEM image of the nanowire junction after plasma treatment; (e) Current-voltage measurement of LED lamps connected by stretchable Cu NW conductors at various strains. Insets are digital photos of the whole setup at 0 and 250% strain[48]

Fig. 6 Schematic diagram (a) of the preparation procedure of Cu NWs/PA electrode. SEM (b), TEM (c), HRTEM (d) and EELS spetra (e) of the Cu NWs film after TiO2 nanopartical sol treatment. Raman spectra (f) of Cu NWs before post-treating, after H2 plasma treatment and TiO2 nanopartical sol treatment. Plot of the transmittance (at a wavelength of 550 nm) with respect to the sheet resistance (g) for ﬁlms of Cu NWs with H2 annealing, H2 plasma treatment and TiO2 nanopartical sol treatment. Sheet resistance variation (h) of the commercial ITO/PET and Cu NWs/PA electrodes during the bending test of 104 cycles[53]

Fig. 7 (a) Time-dependent temperature curves of Cu NW-1000 on PET films at input voltages of 1.5-5 V under ambient conditions; (b) PET/ITO transparent heaters during 104 cycles of bending tests; (c) Infrared photograph and (d) application examples of Cu NW-based stretchable heater[61]

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