Application of Te-Based Glass in Silicon Solar Cells

doi:10.1007/s40195-014-0188-2

Abstract

Abstract:

(90-x)TeO₂-xZnO-10Bi₂O₃ (x = 15, 17.5, 20 and 22.5, in mol%) and 70TeO₂-20ZnO-(10-y)Bi₂O₃-yNa₂O (y = 1, 3, 5, 7, and 10, in mol%) glasses, and the corresponding Ag paste were prepared in order to prove that the Te-based glass frit could be applied to Ag pastes to fabricate Ag electrode. The relationship between structure and properties of the glasses was analyzed. The effects of glass frit on the microstructure, adhesion force, and resistivity of the Ag electrode were studied. The microstructure of Ag electrodes and the phase analysis of interface between Ag electrodes and the Si wafer were investigated using SEM and XRD. Finally, the 70TeO₂-20ZnO-5Bi₂O₃-5Na₂O glass showed better performance in the paste. What is more, Ag crystallites could be found on the Si wafer. These results suggested that the Te-based glass frit could react with SiN_xanti-reflecting coating and Si to serve as a medium for forming Ag crystallites.

Key words: Solar cells, Ag electrode, Silver paste, Tellurite glass, Ag crystallites

Xin-Xin Pi, Xiu-Hua Cao, Zhen-Xiao Fu, Le Zhang, Peng-De Han, Li-Xi Wang, Qi-Tu Zhang. Application of Te-Based Glass in Silicon Solar Cells[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(2): 223-229.

Figures/Tables 11

Fig. 1 Infrared spectra of (90-x)TeO2-xZnO-10Bi2O3 glasses

Table 1 Physicochemical properties of the (90 - x)TeO2-xZnO-10Bi2O3 glass

Sample	T _g (°C)	T _c1 (°C)	T _c2 (°C)	ΔT (°C)	T _f (°C)	α (10^-6/°C)	DR (g cm^-2 min^-1)
x = 15	371	448	566	77	654	9	4.0621 × 10^-8
x = 17.5	377	470	570	97	615	11	4.1458 × 10^-8
x = 20	384	561	N/A	177	610	12	4.2592 × 10^-8
x = 22.5	368	476	578	103	593	15	4.3605 × 10^-8

Fig. 2 DTA thermograms of the investigated glasses in the (90-x)TeO2-xZnO-10Bi2O3 (heating rate is 10 °C/min)

Fig. 3 SEM images of the surface of the Ag electrode a, cross section between Ag electrode and Si wafer b, corresponding to the paste using 70TeO2-20ZnO-10Bi2O3 glass

Fig. 4 Infrared spectra of the 70TeO2-20ZnO-(10-y)Bi2O3-yNa2O glasses

Fig. 5 Raman spectra of the 70TeO2-20ZnO-(10-y)Bi2O3-yNa2O glasses

Table 2 Physicochemical properties of the 70TeO2-20ZnO-(10 - y)Bi2O3-yNa2O glasses and the adhesion force and resistivity of the corresponding Ag electrodes

Sample	T _g (°C)	T _c1 (°C)	ΔT (°C)	T _f (°C)	α (10^-6/°C)	DR (g cm^-2 min^-1)	Ag electrode code	Adhesion force (N)	Resistivity (μΩ cm)
y = 1	375	475	100	573	13	1.3678 × 10^-7	ZN1	2.1	2.6021
y = 3	366	465	99	540	15	2.4239 × 10^-7	ZN2	2.7	2.5378
y = 5	354	457	103	500	16	4.5617 × 10^-7	ZN3	3.3	2.4752
y = 7	330	428	98	485	21	1.0648 × 10^-6	ZN4	4.7	2.4124
y = 10	310	411	101	450	24	2.0216 × 10^-6	ZN5	6.0	2.3569

Fig. 6 Variation of the glass transition temperature, softening temperature, and thermal expansion coefficient with the Na2O content of 70TeO2-20ZnO-(10-y)Bi2O3-yNa2O glasses

Fig. 7 Variation of the dissolution rate with the Na2O content of 70TeO2-20ZnO-(10-y)Bi2O3-yNa2O glasses

Fig. 8 SEM images of the ZN1, ZN3, and ZN5 Ag electrodes: a ZN1 surface; b ZN1 cross section; c ZN5 surface; d ZN5 cross section; e ZN3 surface; f ZN3 cross section; g ZN3 interface

Fig. 9 XRD patterns obtained from the surface ZN3 Ag electrode a, Si surface after removing ZN3 Ag electrodes using HNO3/HF b, Si surface after removing Ag electrodes without glass frit c

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