1SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
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Shubham DUTTAGUPTA, Naomi NANDAKUMAR, John RODRIGUEZSolar Energy Research Institute of Singapore (SERIS), NUS, Singapore
SNEC 2020: 14th Global Advanced PV Technology Conference7-9 Aug 2020
monoPolyTM Technology Platform: Implementation of Passivated Contacts in PERC/T Production Lines
2SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Introduction of the Speakerq Dr Shubham Duttagupta is the Deputy Director of the Silicon Solar
Cells & Modules (SSCM) Cluster at SERIS and also heads the Advanced Silicon Solar Cells Group inside the SSCM Cluster.
q The scientific-technical aim of the research cluster is to develop technologies that target the limit of silicon based single-junction cell & module efficiency while keeping the overall process cost-competitive.
q The research cluster collaborates with several solar cell/module, equipment, automation and material companies to jointly develop next-generation processes.
q Dr Duttagupta’s PhD research focused on the development of advanced multifunctional passivation materials required for high-efficiency crystalline silicon wafer solar cells.
q Recently his research team has won an APVIA Technological Achievement Award at SNEC 2019 and a Research Partner Award at World Solar Congress (WSC) 2019 – both for the monoPoly© high-efficiency silicon solar cell technology.
3SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
About SERISSolar Energy Research Institute of Singapore
q National Lab founded at NUS in 2008; supported by NRF & EDB
q Focuses on applied solar energy research(solar cells, PV modules, PV systems)
q > 160 staff & adjunct researchers; state-of-the-art labs, ISO certified (9001, 17025)
q Close collaborations with industry & government agencies
q Strategic priorities: To develop & commercialise solar technologies suited for urban and tropical applications, and support industry development and the energy transformation towards higher solar adoption
SERIS
Solar cells
PV modules
Solar PV
systems
4SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Main R&D areas of SERIS
Solar cells:§ Silicon solar cells (various
cell architectures)§ Perovskite/silicon tandem
solar cells§ Characterisation &
simulation
Solar PV systems:§ System technologies,
incl. Floating solar§ PV grid integration§ Solar potential & energy
meteorology§ Urban Solar, incl. BIPV§ Quality assurance of PV systems
PV modules:§ Module development § Module testing (indoor &
outdoor)§ Characterisation & simulation§ Module reliability studies,
failure root cause analysis§ Module recycling
5SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Outlineq Motivation
q PERC innovation & evolution q Need for and transition to passivated contact
q SERIS’ bifacial monoPoly™ cell technology
q Strategic vision for evolutionary pathq The monoPolyTM process/platform
q monoPolyTM cells using inline single-side PECVD deposition
Ø monoPolyTM process flowØ monoPolyTM layer propertiesØ I-V results for thinner n+:poly-Si
q Late News: initial results of biPolyTM cells
q Summary
6SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC innovation to industrialisationPassivated Emitter & Rear Cell
~25% efficiency, late 1980s/1990s Industrial Process, 2008 – 2010
~680 mV, ~22%
TEX
ANNEAL
DIF
WET
r + f.PECVD
FIRING
Stabilisation
LASER
Blakers, Zhao, Green et al. (UNSW)
New ProcessOptimisedKnobloch, Aberle et al. (Fraunhofer ISE)
7SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/T Cells[pPERC]
680 mV, ~22.5% 670 mV, ~22%
TEX
WET
DIFF
DIF
WET
r + f.PECVD
FIRING
[nPERT] q PERC: Passivated Emitter & Rear Cell
q Capacity (today): ~90 GW [1]
q Cost (today): $0.24 – 0.28/Wp [1]
q PERC cell efficiency:
Ø 5 – 12 BB eff. PERC cells today are at 22.5 ± 0.5% (best bin, golden line)
Ø May or may not include selective emitter
Ø Record cell reported in R&D: 24% (press-release [2])
TEX
ANNEAL
DIF
WET
r + f.PECVD
FIRING
Stabilisation
[1] ITRPV 2019, [2] LONGi press release (2018/19)
8SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC – with Passivated ContactsBeyond standard PERC/PERT
Ø Passivated Contacts: Voc of ≥ 700 mV due to lower surface recombination losses (J0,metal + J0,passivated)
REQUIREMENTØHigh-throughput, low-cost,
established process techniques for passivated contacts
Ø Easy upgrades to existing PERC/PERT production lines
Ø Thermally stable screen-printed, fire-through metallization
ITRPV 2020
9SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
q Best efficiency on small-area cells: 25.7% (TOPCon), 26.1% (ISFH IBC-POLO)q Industry soon catching up on large-area cells: 24.79% (JinkoSolar) q Still significant gaps for the transfer of technology to mass production!
Poly-Si/SiOx passivated contacts
10SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/PERT
SINGLE-SIDE PASSIVATED CONTACT
Vision “beyond PERC/T”
Ø Based on classical PERC/PERT device structure
Ø Low absorbing poly-Si at either-side
Ø Voc at 680 mV today
Ø Voc of >700 mV is not easy
22.5%
11SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/PERT
SINGLE-SIDE PASSIVATED CONTACTØ Based on classical
PERC/PERT device structure
Ø Low absorbing poly-Si at either-side
Ø Voc at 680 mV today
Ø Voc of >700 mV is not easy
22%
24.5%
Vision “beyond PERC/T”
12SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/PERT
SINGLE-SIDE PASSIVATED CONTACTØ Based on classical
PERC/PERT device structure
Ø Low absorbing poly-Si at either-side
Ø PECVD method to increase bifaciality and very high throughput
Ø Voc at 680 mV today
Ø Voc of >700 mV is not easy
Vision “beyond PERC/T”
13SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/PERT
SINGLE-SIDE PASSIVATED CONTACTØ Based on classical
PERC/PERT device structure
Ø Low absorbing poly-Si at either-side
Ø PECVD method to increase bifaciality and very high throughput
Ø Voc at 680 mV today
Ø Voc of >700 mV is not easy
PERC
Upgraded PERC
Vision “beyond PERC/T”
14SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/PERT
SINGLE-SIDE PASSIVATED CONTACTØ Based on classical
PERC/PERT device structure
Ø Low absorbing poly-Si at either side
Ø Ultra high deposition speed (2 nm/s)
Ø Voc at 680 mV today
Ø Voc of >700 mV is not easy
PERT
Vision beyond “standard” PERC/T
Upgraded PERT / TOPCon
15SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Industrial Platform: monoPolyTM
Passivated Emitter & Rear Cell~25%, late1980s/1990s
Industrial platform ~2017
710 mV, ~23.5%
TEX
DIF
WET
r. n-doped layer
FIRING
Anneal
r. + f. Passivation/ARC
Feldmann, Glunz et al. (Fraunhofer-ISE)
TOPCon~25.7% efficiency, ~2013
New ProcessOptimised
Ø Screen-printing &Ø High-T fired contactsØ Bifacial cell Ø Industrial processØ 2 nm/sec dep. rate
Blakers, Zhao, Green et al. (UNSW)
PERT
16SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
SERIS’ monoPolyTM celle.g. rear-side monoPolyTM scheme
Front PECVD passivation/ARC stack
Screen-printed (& fired) rear metal
contact
Diffused junction
Screen-printed (& fired) rear
metal contact
Rear PECVD layer
n-type or p-type 6” Cz-Si
n+:monoPolyTM layer
Interfacial oxide
17SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
LPCVD
PECVD
APCVD
Industrial Tools for monoPolyTM cell
18SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
SDE + Texture
In-situ oxide + n+:a-Si
Annealing
HF dip
B-diffusion
Rear side etch
n-type
n-typen-typep+
p+
Rear etch
n-typen-type
p+
Thin oxide Poly-Si (n+)
cn-type
p+ emitter
Thin oxide Poly-Si (n+)
Front ARC
SiNx
Solar cell process flow8-step process with inline PECVD poly-Si
[2] Duttagupta et al., SOLMAT 187 (2018)[3] Nandakumar et al., Prog. in Photovolt. 27 (2019)
cn-type
p+
ARC + passivation
19SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
SDE + Texture
In-situ oxide + n+:a-Si
Annealing
HF dip
Screen-printing + Firing
B-diffusion
Rear side etch
8 ST
EPS
Solar cell process flow8-step process with inline PECVD poly-Si
[2] Duttagupta et al., SOLMAT 187 (2018)[3] Nandakumar et al., Prog. in Photovolt. 27 (2019)
ARC + passivation
20SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
monoPolyTM layer propertiesin-situ interfacial oxide layer
Symmetric test structure τeff (µs) iVoc at 1 Sun (mV) J0,pass per side
(fA/cm2)J0,metal per side
(fA/cm2)No oxide formation 1700 711 8.9 -In-situ oxide formed 3000 740 3.0 20
n-Si
SiNx
n+:poly-Sioxide
oxiden+:poly-Si
SiNx
With oxide
n-Si
SiNx
n+:poly-Si
n+:poly-SiSiNx
W/o oxide growth
Test sample structuren+:poly-Si
SiOx
c-Si
5 nm
21SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Ø Reason for low parasitic absorption: High O-content in poly-Si layer!
Ø Poly-SiOx widens bandgap making layer transparent to long wavelength light4
monoPolyTM layer propertiesLow absorbing n+:poly-Si
4Yang et al., APL, 112 (2018)
ED
S A
real
Map
s
LPCVD poly-Si
Si substrate
SiNx
PECVD poly-Si
Si substrate
SiNx
22SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
I-V resultsImprovements in B-emitter and Si wafer
Best group (busbarless) Voc (mV) Jsc (mA/cm2) FF (%) η (%)Batch median 705 41.1 79.2 23.0Best cell 707 41.1 79.7 23.2
23SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
I-V resultsImprovements in B-emitter and Si wafer
η [%]
Isc [mA]
Voc [mV]
FF [%]
Cell area [cm²]
Jsc [mA/cm²]
23.20 9868 707.9 81.20 244.44 40.37*Measurement with rear full-area brass chuck
q External verification at ISFH CalTec
24SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
I-V resultsImprovements in B-emitter and Si wafer
Cell precursor iVoc to cell Voc drop Reverse current characteristics
q Lowly doped emitter shows a higher drop due to higher recombination at the metal contact
q Thinner wafers with lowly doped emitters show lower Irev at -12 V
25SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
monoPolyTM efficiency progress Poly-Si deposited using an advanced PECVD tool
Record Batch Voc (mV)
Jsc (mA/cm2)
FF (%)
η (%)
Record batch (Aug 2019)
708 40.37 81.2 23.2
SDE + Texture
In-situ oxide + n+:a-Si
Annealing
HF dip
Screen-printing + Firing
B-diffusion
Rear side etch
8 ST
EPS
ARC + passivation
qRapid progress – LR of 1%abs/year
qPilot-scale production ongoing with strategic technology partners
Independently Certified by
26SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Initial Module ResultsmonoPolyTM inside
352 W
60 cellsWhite Back Sheet
monoPolyTM inside
TUV
Cer
tifie
d
27SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Upgraded PERT/monoPolyTM PlatformPassivated Emitter & Rear Cell
monoPolyTM Industrial Platform ~2017
710 mV, ~23.5%
TEX
DIF
WET
PECVD n-doped layer*
FIRING
Anneal
r. + f. Passivation/ARC
Ø Screen-printing &Ø High-T fired contactsØ Bifacial cell Ø Industrial process
690 mV, ~23.0%
TEX
DIF
WET
LPCVD poly-Si POCl3
pClean process*
PECVD Process* LPCVD Process*
FIRING
r. + f. Passivation/ARC
*SERIS proprietary
28SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
PERC/PERT
BACK-SIDE PASSIVATED CONTACT
FRONT & BACK-SIDE PASSIVATED CONTACTS
Late News: Vision “beyond PERC/T”
Ø Based on classical HJT device structure
Ø poly-Si at both sides to increase Jsc Ø PECVD layers to enable “thin,
stable and contactable” front-layers
Ø Alternative metallisation pastes to reduce cost and increase stability
Ø Based on classical PERT device structure
Ø Low absorbing poly-Si at rear sides to increase VOC
Ø Voc limits at 680 mV today
Ø Voc of >700 mV is difficult
Advancement - 1
Advancement - 2
25.5%
24.5%
29SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
q Firing-stable “semi-transparent” poly-Si thickness on front ~20 nm q Firing-stable “standard” poly-Si thickness on the rear ~ 50 nm
iVoc [mV]
Jsc* [mA/cm2]
iFF [%]
h max
[%]Cell “precursor“ (244.3 cm2) 730 40.5 85.1 25.1
* parameters for an assumed Jsc of 40.5 mA/cm2
Upgraded high-temperature “heterojunction” cell
Vision “beyond PERC/T”
30SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Summaryq SERIS’ monoPolyTM platform presents a “unique” industrial
solution for PECVD and LPCVD processes suitable for mass production
q Inline, single-side PECVD deposition (CAiA®). q 8-step process flow easily adaptable for mass production.q Low parasitic absorption due to higher O-content in poly-Si.q Thinner PECVD poly-Si layers (20-120 nm) show good
results q Best efficiency using 80-100 nm PECVD n+:poly-Si with no
loss in Jsc
q Peak efficiency of 23.5%, with Voc of ~710 mV!q First modules have power of 345 W (60 cells)q After monoPolyTM; SERIS is strategizing towards biPolyTM
cell development potential is beyond 25% cell efficiency
31SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).
Thank you for your attention!SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB)
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