p-ibc: combining perc and topcon · 2 o 3 perc part topcon part. p-ibc al ag gap advantages no...

P-IBC:

COMBINING PERC AND TOPCON

E.E. BENDE

N. GUILLEVIN

A.R. BURGERS

Y. WU

PERC AND WHAT NEXT?

Al

SiNx

Al2O3

SiNx

SE

Industry : ~22.3% efficiency

Ag

PERC AND WHAT IS NEXT?

Al

n-Poly

Poly fingers

AgDriver

J0,Ag reduction

Challenges

Alignment

Parasitic absorption

Processing

P-IBC: COMBINING PERC AND TOPCON

AlAg

SiNx

Al2O3

SiNx

Al2O3n-poly

PERC

partTOPcon

part

P-IBC

AlAg

gap

Advantages

No front-side shadow

No Boron-diffusion → gap “for free”

Ag & Al metallization, like PERC

n-poly on rear side

Low parasitic absorption

Huge market for “ultra blacks”

Requirements

Modified module interconnection

Double-sided Al2O3

Patterning n-poly with simple process

TWO ARCHITECTURES

Al Ag AgAl

A B

n-Polyi-Polyn-Poly

Local etching n-poly Diffusion barrier process

METALLIZATION OPTION 1

Base region: line-shaped

BSF: line-shaped

LCObase

AgAg

Aln-polyFT Ag


Base region: line-shaped

BSF: dot-shaped

base

AgAg

Aln-polyFT Ag


Base region: dot-shaped

BSF: dot-shaped

base

AgAg

Aln-polyFT Ag

FREEDOM IN METALLIZATION

AlAg

No shunt

Alignment requirement

Al

Ag

Measures to prevent shunt required

Relaxed alignment

Better conduction

QUOKKA 3D

J0 VALUES

Al Ag

n-Poly

10 fA/cm2100 fA/cm2 10 fA/cm2

5 fA/cm2

500 or 1000 fA/cm2

tB=200,300,500,1000 ms

REDUCING J0,AL

1000

M. Rauer et al, IEEE JPV, 2013

500 fA/cm2

• 7 um Al-BSF

• 2.5 um B-Al BSF

QUOKA 3D

RESISTANCES

AlAg

n-Poly

1 / 1.5 / 2.0 Wcm3 mWcm2

3 mWcm2

80 W/sq

QUOKKA 3D


LCOBase Ag

Half pitch

Half

LCO pitch

Emitter

Computational unit cell

ASSUMED AL COVERAGE

LCO Ag

Al print

80 um

30 um

50 um

130 um

VOC

J0,Al=1000 fA/cm2 J0,Al=500 fA/cm

2

pitch [mm]

0.60

0.75

1.00

pitch [mm]

0.60

0.75

1.00

wt= 145 mm

tb= 500 ms

rSi=1.5 Wcm

AL CONDUCTION

Assumptions

Rsh [mW/sq]

BSF: 25,000

Al-Si alloy: 4

Al-bulk: 16

J. Krause et al., Sol. Mat. 95 (2011)

FF


2

pitch [mm]

0.60

0.75

1.00

pitch [mm]

0.60

0.75

1.00

Internal, line, contact

resistance

wt= 145 mm

tb= 500 ms

rSi=1.5 Wcm

EFFICIENCY


2

pitch [mm]

0.60

0.75

1.00

pitch [mm]

0.60

0.75

1.00wt= 145 mm

tb= 500 ms

rSi=1.5 Wcm

EFFICIENCY

wt = 145 mm

finger pitch=750 mm

dot pitch=60 mm

rSi=

1 Wcm

2 Wcm

rSi=

1 Wcm

2 Wcm


2

LAB PROCESS RESULTS

A B

n-Polyi-Polyn-Poly

PROCESS A1 (ETCH BARRIER PRINT)

1 2 3 4

5 6 7 8

AlAg

Oxide & n-poly Etch barrier dielectric Barrier printing Etch n-poly

Etch barrier removal Double-sided

Al2O3-SiNx

PERC-like

laser contact opening

PERC- like

Metallization & co-fire

PROCESS A2 (ALL LASER)

1 2 3 4

5 6 7 8

AlAg

Oxide & n-poly Etch barrier dielectric Etch barrier

laser 1 opening

Etch n-poly

Etch barrier removal Double-sided

Al2O3-SiNx

PERC-like

laser 2 opening

PERC- like

Metallization & co-fire

IMPLIED-VOC

Al2O3-SiNx

Al2O3-SiNx

n-Poly

Test structure Cell precursor

npoly

base

IMPLIED-VOC

Al2O3-SiNx

Al2O3-SiNx

n-Poly

Test structure Cell precursor

npoly

base

J0=6 fA/cm2 J0=5 fA/cm

2

IMPLIED-VOC

Al2O3-SiNx

Al2O3-SiNx

n-Poly

Al2O3-SiNx

n-Poly

Al2O3-SiNx

i-Poly

npoly

base

Test structure Cell precursor Test structure Cell precursor

P-IBC CELL PROCESS RESULTS

Two runs

Voc = 680 mV

Shunt issues

Challenges

Pinholes

IQE

Where does the loss come from?

5%

LBIC MEASUREMENT

Contacting LBIC area

LBIC

FT Ag finger

Toyo Al pasteAl finger

Base

NC Ag busbar

Electrical shading

Emitter BB has strong LBIC signal

Base BB causes electrical shading

Ag FT fingers not visible

(passivatived contact)

Al has lowest signal as expected

Al and Ag show a reaction that

adversely affect Al2O3/SiNx

passivation

Glass frit migration issue

due to non-compatibility

3rd party

NC paste

Al2O3(6nm)/SiNx(80nm)

PINHOLES

pinhole case 1

pinhole case 2pinhole case 3

processing

Prepare for patterning Cell before metallization

LCO

paste

Dielectric

Etch barrier

Pinholes visible on n-Poly, not at base 33

Al

Ag

Al

Ag

nPolyAg

Ag

nPoly

Ag

nPoly

Al

base

Sharp transition from “dirty” to “clean” n-Poly

base

PL

No pinholes visible

SHUNT OF AL FINGERS ON N-POLY

Al

LASER PATTERNING

processing

LASER OPENING BASE AREA (N-POLY PATTERNING)

Speed (%)100 50 3565

50%

65%

85%

100%

Power

703 mV 719 mV 724 mV 719 mV

710 mV 710 mV 720 mV715 mV

680 mV668 mV 682 mV 707 mV

Not measured

Optical microscopeLaser affects bulk

R_SHEET MAP

Speed (%)100 50 3565

50%

65%

85%

100%

Power 60 65 70 75 80 85 90 95

110.6110.8111.0111.2111.4

0.000

56.64

113.3

169.9

226.6

283.2

339.8

396.5

453.1

500.0

Rsheet mapping by THz-technique

n-poly fully removed

CONCLUSION

p-IBC combines PERC & TOPcon

Implied-Voc values from 690-720 mV (after firing)

Laser patterning has high potential for solar-cell processing

R&D focus on preventing shunt

thicker SiNx

no tail in base region

no pinholes

p-IBC is a high-potential candidate as follow-up for PERC in industry

ECN.TNO seeks industrial collaboration to bring this or other concepts further

[email protected]

Acknowledgement to Toyo Aluminum

mailto:[email protected]

THANK YOU

FOR YOUR ATTENTION

Thanks to:

• Co-authors,

• Project ABC4All partners, RVO TKI funding

• Toyo Aluminium

p-ibc: combining perc and topcon · 2 o 3 perc part topcon part. p-ibc al ag gap advantages no...

Documents