RESEARCH CENTER JLICH GMBH, JLICH, GERMANY INSTITUTE OF ENERGY AND - PowerPoint PPT Presentation

RESEARCH CENTER JÜLICH GMBH, JÜLICH, GERMANY INSTITUTE OF ENERGY AND CLIMATE RESEARCH 5 – PHOTOVOLTAICS INNOVATION IN THIN-FILM MATERIAL AND PROCESSING FOR SILICON SOLAR CELL 25.02.2019 K.DING, A.LAMBERTZ, W.DUAN, M.POMASKA, A.GAD, K.BITTKAU

RESEARCH IN GERMANY 22.03.2019 2

RESEARCH CENTER JUELICH 22.03.2019 3

IEK-5 PHOTOVOLTAICS Research groups: 6 Staff: ~100 Helmholtz RC Jülich IEK-5 PV 22.03.2019 4

MOTIVATION SHJ Silicon thin- film „DNA“ at IEK-5  Si thin-films  Si alloys  TCO films  Multijunction  Light management  Laser processing  … Key expertise is application of novel material and process in SHJ solar cells 22.03.2019 5

SHJ (c-Si) GROUP Main collaborator for c-Si activities  Establishing a baseline for industrial sized (156 x 156 mm²) SHJ solar cells  Establishing a baseline for silicon solar modules for vehicle integrated PV  Establishing a process and characterization standard for passivated contact solar cells  Application of silicon alloys and HWCVD processes in SHJ solar cells 22.03.2019 6

DEVICE TYPE „ Rear emitter M2 size SHJ solar cell  µc-Si:H and µc-SiOx:H etc.  IWO, ITiO, AZO etc.  Smartwire  Thin wafers (<40 µm)  Pero-Si-Tandem 22.03.2019 7

SILICON HETEROJUNCTION BASELINE For industrial sized SHJ solar cells Wafer Silicon TCO Silver screen Cell STEP 1 STEP 2 STEP 3 STEP 4 STEP 5 pretreatment deposition sputtering printing characterization 22.03.2019 8

SILICON HETEROJUNCTION BASELINE For industrial sized SHJ solar cells 40  High solar cell efficiency Current density [mA/cm 2 ]  Reproducible and homogeneous process 30  High throughput J sc [mA/cm²] V oc [mV]  Fast feed back 20 37.4 724  Industrial scalable tools ƞ [%] FF [%]  Established platforms 10 78.8 21.4  Test materials and processes for ƞ > 25% 0 0 200 400 600 Voltage [mV] 22.03.2019 9

NANOCRYSTALLINE SILICON OXIDE Transparent and conductive window layer  Deposited by PECVD, both n- and p-type possible  Industrial compatible/transferable process  Fully compatible with SHJ solar cell technology A. Richter, et.al. (2017) Sol. Energy Mater. Sol. Cells, 174, 196 – 201. 22.03.2019 10

NANOCRYSTALLINE SILICON OXIDE Good uniformity of material properties 2.4 10 a E 04 on a-position [eV]  on a-position [S/cm] 2.3 e 0.01 2.2 1E-5 2.1 1E-8 2.0 2.0 2.1 2.2 2.3 2.4 1E-8 1E-5 0.01 10  on e-position [S/cm] E 04 on e-position [eV] 22.03.2019 11

VEHICLE INTEGRATED PV SHJ solar cell for integration in automobile industry Audi New aspects on cell requirement:  High demand on aesthetics  Flexibility in cell size required StreetScooter 22.03.201 12 9 22.03.2019 12

MICROCRYSTALLINE SILCON CARBIDE Transparent and low-T passivated contact effective minority carrier SiC/SiO 2 passivation 10 τ eff (10 15 ) = 2.2 ms lifetime t eff [ms] iV oc = 731 mV 1 10 14 10 15 10 16 minority carrier density D p [cm -3 ]  Deposited by HWCVD  Low-T process compatible with SHJ  Highly transparent SiO 2 /SiC stack  High passivation quality M. Pomaska, et.al. (2015) Thin Solid Films, 595, 217 – 220. 22.03.2019 13

TRANSPARENT PASSIVATED CONTACT µc-SiC:H(n)/SiO 2 passivation deteriorated during ITO sputtering  iV oc limited  J sc decreased J sc η FF V oc R s (mA/c (%) (%) (mV) ( Ω cm²) First low-T transparent m²) passivated contact SiC/SiO 2 19.7 38.7 71.5 712 2.1 Ref. 19.9 36.1 75.7 727 1.4 22.03.2019 14

POLY-SI PASSIVATED CONTACT Process chain: Ag Ag 1. growth of ca. 1.5 nm tunnel oxide 2. HWCVD n-doped layer (Si, SiO SiC) SiN x 3. furnace anneal @ 800-900 °C 4. deposition of ca. 80 nm SiN x layer a-/nc-Si:H(n) poly-Si(n+) 5. Screen print Ag-contacts SiO x 6. fire contacts @ 850 °C Currently best i V oc : 731 mV c-Si(n) (with R sheet = 142 Ω □ and deposition rate of 42 nm/min 22.03.2019 15

CHARACTERIZATION JOSEPH Understanding the passivated contact 22.03.2019 16

SUMMARY  Research Center Jülich works on SHJ and Pass. Con.  Key expertise is thin-film materials and processes for SHJ  Industrial sized processes  Unique Si-alloy materials and HWCVD processes 22.03.2019 17

ACKNOWLEDGEMENT Thank you for your attention! 22.03.2019 18

CATALYTIC DOPING Post deposition treatment for SHJ solar cell  Increase in P doping (ECV, SIMS)  Increase in lifetime (QSSPC)  No impact on optics (PDS)  Good synergy by combining cat- doping and SHJ technology  Post deposition treatment to engineer the thin-films and the interfaces Y. Liu, et.al., (2017) Thin Solid Films, 635, 63 – 65 . 22.03.2019 19

DIFFUSION OF PHOSPHORUS Doping mechanism and application in cell +0.3 % absolute 22.03.2019 20