Degradation Mechanism of Silver Nanowire Transparent Conductive Films: a Review

doi:10.15541/jim20190098

Abstract

Abstract:

Silver nanowire transparent conductive film is one of the new indium-free electrode materials. It has attracted increasing attention from academia and industry due to its superior optoelectronic properties and excellent flexibility. It has been employed in a wide variety of applications in displays, touch panels, solar cells, smart heaters, electromagnetic interference shielding, and so on. However, silver nanowire transparent conductive film has a serious stability issue in service, for example, break or spheroidization above 300 ℃ under fulfidation, accelerating the degradation under ultraviolet light, pores for mation or even breakdown due to electromigration. In this review, the degradation phenomena is thoroughly introduced, the degradation mechanisms is analyzed, and the remedy strategy of degradation is discussed.

Key words: silver nanowires, transparent conductive films, degradation mechanism, electromigration, sulfidation, review

CLC Number:

TQ174

YE Chang-Hui, GU Yu-Jia, WANG Gui-Xin, BI Li-Li. Degradation Mechanism of Silver Nanowire Transparent Conductive Films: a Review[J]. Journal of Inorganic Materials, 2019, 34(12): 1257-1264.

Figures/Tables 8

Fig. 1 Different failure modes of silver nanowires (a) Chemical corrosion[10]; (b) Thermal failure[15]; (c) Joule heat failure[18]; (d) Electromigration[27]

Fig. 2 TEM images of the same AgNW sample stored for different time after exposure to air at ambient condtions[10] (a) The sample just after synthesis; (b) The sample stored for 3 w; (c-e) The sample stored for 4, 5, and 24 w, respectively; (f) High-resolution TEM image of one of the crystallites that compose the shell with inset showing to the FFT of the image

Table 1 Interplanar distances and angles between lattice planes from the FFT in Fig. 2(f)[10]

Parameters	Measured values	Theoretical values
d₍₀₁₃₎/nm	0.242	0.242
d₍₁₁₁₎/nm	0.305	0.308
${{d}_{(10\bar{2})}}/\text{nm}$	0.311	0.311
(013) ∠ (111)/(°)	49.1	50.0
(111) ∠ $(10\bar{2})$./(°)	79.2	79.4
$(10\bar{2})$.∠ (013)/(°)	51.7	50.6

Fig. 3 Schematic representation of a junction between two adjacent AgNWs[12] (a) As-deposited junction; (b) Local sintering; (c) Initiation of the deterioration of the junction; (d) SEM image of a AgNW junction after thermal load just before the failure point; (e-g) SEM images of bare AgNW electrodes (e) Before annealing and after annealing for (f) 200 ℃, 20 min and (g) 380 ℃, 20 min[14]

Fig. 4 (a) Finite-element simulation of the current flow through a two AgNW junction[22]; (b, c) SEM images of a 12 □/sq AgNW electrode under a constant current density of 17 mA/cm2 for 17 d [21]; (d-f) SEM image of AgNW network under Joule heating[22]: (d) Local fracture of the AgNW network; (e) Expansion of hot spots; (f) Hot spots merge to form an electrically discontinuous region

Fig. 5 The morphology of the small nanodots and large particles emerged on/around silver nanowires after light irradiation[23] (a) The small nanodots on/around single AgNW; (b) The small nanodots on/around AgNWs with different diameters; (c) The small nanodots at the end of AgNW and also the large particle at the wire-wire junction with inset showing the high magnification image; (d) The large particle adjoined AgNWs

Fig. 6 SEM images of a bi-crystalline AgNW under a current of 54 mA[26] (a) Prior electrical stressing; (b-e) The direction of vacancy movement when the current flows to the left; (f-i) The direction of vacancy movement when the current moves to the right; (k-n) Surface morphology SEM images of the AgNW network in different stages of degradation[27]: (k) Fresh sample; (l) Degradation with larger grain size; (m) The emergence of larger voids; (n) Complete breakdown

Fig. 7 Remedy strategy of silver nanowire degradation (a) A self-assembled organic 2-mercaptobenzimidazole (MBI) used as an inhibitor of AgNWs[28]; (b) ZnO-AgNW composite electrode prepared by AP-SALD[12]

References 31

[1]	SHANG Z, LI J, FAN C , et al . In situ study on surface roughening in radiation-resistant Ag nanowires. Nanotechnology, 2018,29(21):215708.
[2]	BELLET D, LAGRANGE M, SANNICOLO T , et al. Transparent electrodes based on silver nanowire networks: from physical considerations towards device integration. Materials, 2017,10(6):570.
[3]	SUN Y, GATES B, MAYERS B , et al. Crystalline silver nanowires by soft solution processing. Nano Lett., 2002,2(2):165-168.
[4]	LEE J Y, CONNOR S T, CUI Y , et al. Solution-processed metal nanowire mesh transparent electrodes. Nano Lett., 2008,8(2):689-692.
[5]	LIANG G, YI M, HU H , et al. Coaxial-structured weavable and wearable electroluminescent fibers. Adv. Electron. Mater., 2017,3(12):1700401.
[6]	SCHUETTE W M, BUHRO W E . Silver chloride as a heterogeneous nucleant for the growth of silver nanowires. ACS Nano, 2013,7(5):3844-3853.
[7]	CHEN C, ZHAO Y, WEI W , et al. Fabrication of silver nanowire transparent conductive films with an ultra-low haze and ultra-high uniformity and their application in transparent electronics. J. Mater. Chem. C, 2017,5(9):2240-2246.
[8]	VOLOE L, PETERSON P J . The atmospheric sulfidation of silver in a tubular corrosion reactor. Corros. Sci., 1989,29(10):1179-1196.
[9]	FRANEY J P, KAMMLOTT G W, GRAEDEL T E . The corrosion of silver by atmospheric sulfurous gases. Corros. Sci., 1989,25(2):113-143.
[10]	ELECHIGUERRA J L, LOPEZ L L, LIU C , et al. Corrosion at the nanoscale: the case of silver nanowires and nanoparticles. Chem. Mater., 2005,17(24):6042-6052.
[11]	GRAEDEL T E, FRANEY J P, GUALTIERI G J , et al. On the mechanism of silver and copper sulfidation by atmospheric H₂S and OCS. Corros. Sci., 1985,25(12):1163-1180.
[12]	KHAN A, NGUYEN V H, ROJAS D M , et al. Stability enhancement of ailver nanowire networks with conformal ZnO coatings deposited by atmospheric pressure spatial atomic layer deposition. ACS Appl. Mater. Interfaces, 2018,10(22):19208-19217.
[13]	ZHANG X, YAN X, CHEN J , et al. Large-size graphene microsheets as a protective layer for transparent conductive silver nanowire film heaters. Carbon, 2014,69:437-443.
[14]	HWANG B, AN Y, LEE H , et al. Highly flexible and transparent Ag nanowire electrode encapsulated with ultra-thin Al₂O₃: thermal, ambient, and mechanical stabilities. Sci. Rep., 2017,7:41336.
[15]	AHN Y, JEONG Y, LEE Y . Improved thermal oxidation stability of solution-processable silver nanowire transparent electrode by reduced graphene oxide. ACS Appl. Mater. Interfaces, 2012,4(12):6410-6414.
[16]	LAGRANGE M, LANGLEY D P, GIUSTI G , et al. Optimization of silver nanowire-based transparent electrodes: effects of density, size and thermal annealing. Nanoscale, 2015,7(41):17410-17423.
[17]	LAGRANGE M, SANNICOLO T, ROJAS D M , et al. Understanding the mechanisms leading to failure in metallic nanowire- based transparent heaters, and solution for stability enhancement. Nanotechnology, 2017,28(5):055709.
[18]	KHALIGH H H, XU L, KHOSROPOUR A , et al. The Joule heating problem in silver nanowire transparent electrodes. Nanotechnology, 2017,28(42):425703.
[19]	SANNICOLO T, CHARVIN N, FLANDIN L , et al. Electrical mapping of silver nanowire networks: a versatile tool for imaging network homogeneity and degradation dynamics during failure. ACS Nano, 2018,12(5):4648-4659.
[20]	FANTANAS D, BRUNTON A, HENLEY S J , et al. Investigation of the mechanism for current induced network failure for spray deposited silver nanowires. Nanotechnology, 2018,29(46):465705.
[21]	KHALIGH H H, GOLDTHORPE I A . Failure of silver nanowire transparent electrodes under current flow. Nanoscale Res.Lett., 2013, 8(1):235.
[22]	CHEN D, ZHAO F, TONG K , et al. Mitigation of electrical failure of silver nanowires under current flow and the application for long lifetime organic light-emitting diodes. Adv. Electron. Mater., 2016,2(8):1600167.
[23]	WANG J, JIU J, ZHANG S , et al. The comprehensive effects of visible light irradiation on silver nanowire transparent electrode. Nanotechnology, 2018,29(43):435701.
[24]	LEE G P, SHI Y, LAVOIE E , et al. Light-driven transformation processes of anisotropic silver nanoparticles. ACS Nano, 2013,7(7):5911-5921.
[25]	GRILLET N, MANCHON D, COTTANCIN E , et al. Photo- oxidation of individual silver nanoparticles: a real-time tracking of optical and morphological changes. J. Phys. Chem. C, 2013,117(5):2274-2282.
[26]	SINDERMANN S P, LATZ A, SPODDIG D , et al. Lattice degradation by moving voids during reversible electromigration. J. Appl. Phys., 2014,116(3):034502.
[27]	CHEUK K W, PEI K, CHAN P K L . Degradation mechanism of a junction-free transparent silver network electrode. RSC Adv., 2016,6(77):73769-73775.
[28]	LIU G S, XU Y, KONG Y , et al. Comprehensive stability improvement of silver nanowire networks via self-assembled mercapto inhibitors. ACS Appl. Mater. Interfaces, 2018,10(43):37699-37708.
[29]	DENG B, HSU P C, CHEN G , et al. Roll-to-roll encapsulation of metal nanowires between graphene and plastic substrate for high-performance flexible transparent electrodes. Nano Lett., 2015,15(6):4206-4213.
[30]	RAMASAMY P, SEO D M, KIM S H , et al. Effects of TiO₂ shells on optical and thermal properties of silver nanowires. J. Mater. Chem., 2012,22(23):11651-11657.
[31]	CHEN D, LIANG J, LIU C , et al. Thermally stable silver nanowire-polyimide transparent electrode based on atomic layer deposition of zinc oxide on silver nanowires. Adv. Funct. Mater., 2015,25(48):7512-7520.