当前位置:首页 >> 能源/化工 >>

太阳级硅中杂质对电池效率的影响(英文)


Specification of solar grade silicon: How impurities affect efficiency
Bart Geerligs

20th EPVSEC Barcelona 2005, 2AO1.3

Outline
Objective and introduction I

ngots and cells from artificially contaminated silicon feedstock: – Titanium – Aluminum Analysis of results Implications for feedstock specification

20th EPVSEC Barcelona 2005, 2AO1.3
2

Objective
Determine allowable concentrations of impurities in silicon feedstock for mc-Si solar cells. Reasons: specific Silicon produced for Photovoltaics possibility of Low-cost and abundant Silicon feedstock from carbothermic reduction of quartz. SiO2 + 2C → Si + 2CO Fe, Ti, Al, and C are major impurities in silicon from carbothermic reduction. What are the target levels for these impurities?
20th EPVSEC Barcelona 2005, 2AO1.3
3

Which specs are available?
Si wafer manufacturers: “we like to be on the safe side, the SEMI poly-Si spec [<0.1 ppmw total metals] works for us…” For PV, there exist more specific earlier studies:

J.R. Davis, et al., IEEE Trans El. Dev. ED-27, 677 (1980) Cz-growth

also, Fally et al., Revue Phys. Appl. 22, 529 (1987) mc-Si, but no info on Ti

20th EPVSEC Barcelona 2005, 2AO1.3
4

Experimental procedure

poly-Si feedstock with added impurity

directional solidification furnace

ingot & wafers

20th EPVSEC Barcelona 2005, 2AO1.3
5

Experimental procedure

poly-Si feedstock with added impurity

directional solidification furnace industrial in-line cell process SiNx:H coating 14.5 – 15% cell efficiency

ingot & wafers

20th EPVSEC Barcelona 2005, 2AO1.3
6

Titanium
10 ppmw (parts-per-million by weight) of Ti were added to the feedstock
20

JscVoc (W/cm )

2

18

15%rel

25%rel

16 reference S10: Ti 0 20 40 60 80 100

14

position in ingot towards top (%)

20th EPVSEC Barcelona 2005, 2AO1.3
7

Titanium
10 ppmw (parts-per-million by weight) of Ti were added to the feedstock
20 0
IQE (%)

18

16 reference S10: Ti 0 20 40 60 80 100

-50

14

-100

ingot S10, position in ingot: 13% 19% 24% 54% 65% 86% 400 600 800 1000 1200 wavelength (nm)

JscVoc (W/cm )

2

position in ingot towards top (%)

Reduction of Jsc due to strongly reduced red-response in IQE
20th EPVSEC Barcelona 2005, 2AO1.3
8

Aluminum
5 ppmw of Al were added to the feedstock
20

JscVoc (W/cm )

2

16

15%rel

25%rel

12

reference S6: Al 0 20 40 60 80 100

position in ingot towards top (%)

20th EPVSEC Barcelona 2005, 2AO1.3
9

Aluminum
5 ppmw of Al were added to the feedstock
20 0 JscVoc (W/cm )
2

16

IQE (%)

-50

12

reference S6: Al 0 20 40 60 80 100 -100

ingot S6, position in ingot: 14% 30% 53% 69% 400 600 800 1000 1200

position in ingot towards top (%)

wavelength (nm)

Reduction of Jsc again due to reduced red-response in IQE

20th EPVSEC Barcelona 2005, 2AO1.3
10

Analysis of results
15-25% reduction of JscVoc due to 5 ppmw Al or 10 ppmw of Ti is too much to be acceptable. How can we determine the maximum allowable concentration? Can the cell efficiency for other concentrations be modeled and predicted? Is there experimental data to verify such a model?

20th EPVSEC Barcelona 2005, 2AO1.3
11

Model for analysis
5

segregation during ingot growth

4 Cs (a.u.) 3 2 1 0.0 0

1 impurity concentration Cs ∝ 1 x

0.2 0.4 0.6 0.8 1.0 20 40 60 80 100 position in ingot x position in ingot towards top (%)

20th EPVSEC Barcelona 2005, 2AO1.3
12

Model for analysis
1 5 Leff in solar cell (a.u.) Cs (a.u.)

segregation during ingot growth

4 3 2
top 1 0 0.0 0 bottom

1 impurity concentration Cs ∝ 1 x
If impurity dominates recombination

1 1 ∝ ∝ Cs 2 Leff τ eff
Leff ∝ 1 x

0.4 (1-x) 0.6 0.8 1.0 1 √ (square root ofposition in ingot xtowards bottom) position in ingot

0.2

Leff can be determined from the red-response of the IQE
20th EPVSEC Barcelona 2005, 2AO1.3
13

Comparing Leff from IQE with model
Leff follows expected decrease to top of ingot. (exception: bottom of S6)
Leff (m) from IQE 150 S10 (Ti) S6 (Al)

100

50
top 0 0.0 bottom

0.6 0.8 1.0 √(1-x) (square root of position towards bottom of ingot)

0.2

0.4

20th EPVSEC Barcelona 2005, 2AO1.3
14

Comparing Leff from IQE with model
Leff follows expected decrease to top of ingot. (exception: bottom of S6) Conclusion: Relation between feedstock contamination and recombination is linear (no non-linear effects from precipitation, etc.).
Leff (m) from IQE 150 S10 (Ti) S6 (Al)

100

50
top 0 0.0 bottom

0.6 0.8 1.0 √(1-x) (square root of position towards bottom of ingot)

0.2

0.4

20th EPVSEC Barcelona 2005, 2AO1.3
15

Comparing Leff from IQE with model
Leff follows expected decrease to top of ingot. (exception: bottom of S6) Conclusion: Relation between feedstock contamination and recombination is linear (no non-linear effects from precipitation, etc.). (at least for Al, Ti, for the used concentrations and probably lower)
20th EPVSEC Barcelona 2005, 2AO1.3
16

Leff (m) from IQE

150

S10 (Ti) S6 (Al)

100

50
top 0 0.0 bottom

0.6 0.8 1.0 √(1-x) (square root of position towards bottom of ingot)

0.2

0.4

Do-It-Yourself specification of solar grade silicon
1. Construct PC1D model for your cell process, and calculate cell efficiency versus Leff 2. Use 1/Leff2 ∝ CL (CL is impurity concentration in the feedstock) “generic” plot of cell efficiency versus CL (CL in a.u.). 3. One data point (impurity concentration and cell efficiency) to calibrate CL-scale. 4. Choose acceptance level of cell efficiency (cost analysis! e.g. 97%rel efficiency if feedstock 25% lower cost). 5. Read required impurity concentration from plot.

20th EPVSEC Barcelona 2005, 2AO1.3
17

Graphical presentation of D-I-Y feedstock specification
relative to high-purity feedstock
14.5% cell techn. 17% cell techn.

1.0

cell efficiency (%rel)

0.9

0.8

our results: 5 ppmw Al or 10 ppmw Ti

0.7

1 10 100 impurity concentration (a.u.)
20th EPVSEC Barcelona 2005, 2AO1.3

18

Graphical presentation of D-I-Y feedstock specification
relative to high-purity feedstock
14.5% cell techn. 17% cell techn.

1.0

cell efficiency (%rel)

0.9

0.8

our results: 5 ppmw Al or 10 ppmw Ti 60x reduction

0.7

1 10 100 impurity concentration (a.u.)
20th EPVSEC Barcelona 2005, 2AO1.3

19

Graphical presentation of D-I-Y feedstock specification
relative to high-purity feedstock

1.0

spec: 0.1 ppmw Al or 0.2 ppmw Ti

14.5% cell techn. 17% cell techn.

cell efficiency (%rel)

0.9

0.8

our results: 5 ppmw Al or 10 ppmw Ti 60x reduction

0.7

1 10 100 impurity concentration (a.u.)
20th EPVSEC Barcelona 2005, 2AO1.3

20

Conclusions
Clear impact of Ti and Al at ppm level. Dependence of impact on position in ingot modeled according to segregation and linear relation between Leff-2 and Cfeedstock. Extrapolated feedstock specification based on 3%rel cell efficiency reduction: Al: 0.1 ppmw Ti: 0.2 ppmw See the paper for more details, also on carbon, mix of impurities, Fe, and modelling of economics!
20th EPVSEC Barcelona 2005, 2AO1.3
21

Thank you for your attention
Acknowledgements Oyvind Mjs, NTNU Trondheim ScanArc, Scanwafer, HCT EC for contracts SOLSILC, SPURT, and SISI Coauthors: Petra Manshanden, Paul Wyers (ECN Solar Energy), Eivind vrelid, Ola Raaness, Aud Waernes (Sintef), Benno Wiersma (Sunergy)

22

22

20th EPVSEC Barcelona 2005, 2AO1.3 20th EPVSEC Barcelona 2005, 2AO1.3


相关文章:
晶硅太阳电池效率提升方向及影响各电性能参数的因素
硅太阳电池效率提升方向及影响各电性能参数的因素_能源/化工_工程科技_专业资料...p, 式中 NA 是受主杂质 浓度;而在 n 形材料中, n ? ND 和 p ? n ...
硅片厚度对电池性能影响
硅片厚度对多晶硅太阳电池性能的影响摘要: 为了进一步降低多晶硅太阳电池的成本, 研究了硅片厚度对多晶硅太阳电池的短路电 流密度、开路电压和效率的影响。可以看出,...
太阳能电池重点答案(前4章)
现代太阳电池,转换效率达到 6%,这是太阳电池...答:半导体中的杂质和缺陷会在禁带间隙中产生允许能级...对硅太阳电池来说,经由陷阱的复合(SRH)为主要的...
影响太阳电池光电转换效率的因素和提高转换效率的主要...
影响太阳电池光电转换效率的因素及提高太阳电池效率的...光生电子 -空 穴对在空间电荷区中产生后,立即被...体内杂质和微观缺陷、PN 并联电阻是由边缘漏电、 ...
金属杂质对多晶铸锭的影响
铸造多晶硅中的金属杂质及其对硅片性能的影响研发技术部 习海平 工号 02575 摘要:铸造多晶硅中金属杂质对太阳电池的转换效率有重要影响,金属杂质的含量与多晶硅片...
杂质对铅酸蓄电池的危害
杂质对铅酸蓄电池的危害_化学_自然科学_专业资料。杂质对铅酸蓄电池的危害 铜、...铅膏中加甘油,与铅粉形成甘油脂,可提高极板强度;木醣醇可能对正极半有影响, ...
如何提高太阳能电池转换效率
效率 引言商业化晶体硅太阳电池的效率一般在 14%—17%由于电池效率队、对...作用:形成杂质接收器,有除杂的效果。 (8)背反射器 ) (9)背面织构化 )(10...
铸造多晶硅中的金属杂质及其对硅片性能的影响aaa
特别是过渡金属杂质, 在原生铸锭的浓度般都低于 1×10” cm 3, 但是它们无论是以单个原子形式,或者以沉淀形式出现,都对太阳电池的转换 效率有重要的影响。...
害杂质对镍镉电池性能的影响
杂质对镍镉电池性能的影响 在镍镉电池中,铁,锰,铜,铬,硝酸盐,碳酸根离子,氯离子及许多有机化合物对电池性能有害。 1,铁使正极的氧过电位明显下降,充电效率...
太阳能电池生产工艺
可在电池 工艺方面采取措施降低晶界及其他杂质的影响...(五)太阳级硅的研发 . 快速发展的晶体硅太阳能...在浓度 1013—1014/cm3 即对电池效率产生很大影响。...
更多相关标签: