EFFICIENCY AND PRODUCTIVITY INCREASE OF SOLAR-CELLS AND -MODULES BY INNOVATIVE LASER APPROACHES

EFFICIENCY AND PRODUCTIVITY INCREASE OF SOLAR-CELLS AND -MODULES BY INNOVATIVE LASER APPROACHES PD Dr. Alexander Horn, V. Schütz, J. Gonzalez, C.C. Kalmbach Photovoltaics Group Dpt. for Production and Systems Email: a.horn@lzh.de Web: www.lzh.de Laser Zentrum Hannover, Germany 28.09.2012

LASERS IN PHOTOVOLTAICS PRODUCTION Drilling Texturing Cutting Welding Soldering Annealing Ablation dielectric layer Ablation Organic layers Structuring Laser Edge Delation others 2

IMPROVEMENT APPROACHES WITH LASERS Efficiency v.s. Productivity Parallelization Optimization Splitting the beam Spatial beam shaping Temporal beam shaping Energy management (e.g. wavelenth, pulse duration, repetition rate) Acceleration Increasing repetition rate Spatial beam shaping 3

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module 4

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module 5

BEAM SHAPING FOR PRODUCTIVITY INCREASE Laser setup with an additional diffractive optical element (DOE) Beam Expander Mirror DOE Scanner f-theta objective Laser Source SHG Mirror Haupt O., Schütz V., and Stute U. Proc. SPIE 7921, 79210V, doi:10.1117/12.876102, 2011 * measured with Primes MSM 6

BEAM SHAPING Single spot Laser spots diffracted by one DOE 1 x 3 1 x 7 1 x 81 5 x 5 0 th and1 st diffration order larger diffration orders 7

BEAM SHAPING FOR EFFICIENCY INCREASE Gauss Top-Hat Gaussian spatial intensity distribution features a tipically Ablation threshold [W/cm²] intensity peak centered within the beam profile Top-Hat features an uniform I [W/cm 2 ] r [m] r [m] power distribution Improvement ablation quality of thin films through beam shaping 8

EXAMPLE: LASER STRUCTURING OF CIGS SOLAR MODULES Improvements in P2 structuring Gauss Top-Hat Module lay-out ZnO:Al-Layer 400-900 nm ZnO-Layer 50-100 nm CIGS Mo CIGS Mo P1 P2 P3 CdS-Layer~50 nm CI(G)S-Layer ~2 µm Mo-Layer ~0,5 µm 20 45 µm 20 45 µm Glass substrate E P = 2 µj; v f = 0,1 m/s (Multiple pass, 4x) E P = 4,4 µj; v f = 0,1 m/s (Multiple pass, 3x) Increased process window Reduced HAZ P1 P2 P3 All 3 laser patterning steps with shaped beam 20 45 µm 20 45 µm 20 45 µm E P = 34 µj; v f = 2 m/s E P = 6,5 µj; v f = 0,1 m/s (Multiple pass, 2x) E P = 8 µj; v f = 2 m/s Experimental set-up using sub-nanosecond laser radiation at 532 nm 9

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module 10

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module 11

SETUP FOR THE FUNDAMENTAL INVESTIGATION Beam Expander Mirror Scanner f-theta objective Laser Source SHG Mirror TRUMPF TRU MICRO 5050 Average Power 50 W @ 1030 nm Pulse duration 7 ps Wavelength 1030 nm/515 nm Repetition rate Up to 400 khz Silicon Poly-Si Size 5 squared Isotextured 12

SILICON ABLATION CHARACTERISTICS 13

FORMATION OF STRUCTURES 0. untreated silicon 1. regular ripple pattern 2. pearl-like structures 3. cone-like structures Bonse 09 Sarnet 08 Nayak 11 larger energy dose I. Formation of ripples at defects II. Formation of regular ripple pattern III. Transformation to pearl-like structure IV. Transformation to cone-like structures 14

STRUCTURING OF SILICON Different topologies at the same laser fluence and different focal diameters Topology is mainly a function of laser fluence and number of pulses per point 15

STRUCTURING OF SILICON Increased structure height with larger number of pulses per point Large variety of achievable topologies Schütz, V. et al. Proc. of SPIE Vol. 8244 82440 X1-7 (2012) 16

PROCESSING OF LARGE-SCALE SILICON WAFERS 5 isotextured Si wafer 7-spots multi-beam processing 15 minutes overall processing time Schütz, V. et al. Proc. of SPIE Vol. 8244 82440 X1-7 (2012) 17

PROCESSING OF LARGE-SCALE SILICON WAFERS Decreased reflectivity of absolute 10% due to laser processing At certain laser parameters no dependence on crystall orientation Processing of large areas with diffractive optical element Schütz, V. et al. Proc. of SPIE Vol. 8244 82440 X1-7 (2012) 18

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module 19

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module 20

LASER STRUCTURING OPV CHALLENGES Goal: monolithic series connection Remove a predominantly transparent thin layer Requirement: obtaining minimal bur and minimal damage of the substrate or layer below Economically feasible for roll-to-roll mass production 21 Project PPP Nr: 13N9847

POLYMER SOLAR CELL AND MODULE Principles and materials PEDOT:PSS P3HT PCBM 22

LAY-OUT AND LASER SELECTION CRITERIA Module lay-out Transmittance of single layers GEN1: With ITO Patterning step P1 Material ITO + PEDOT:PSS Typical thicknesses 125 + 40 [nm] Function Semi-transparent electrode P2 P3HT:PCBM 200 [nm] Photoactive-layer P3 Aluminium 200 [nm] Back contact GEN2: Without ITO Patterning step P1 P2 Material High cond. PEDOT:PSS PCDTBT: PCBM Typical thicknesses 150 [nm] Function Semi-transparent electrode 200 [nm] Photoactive-layer P3 Aluminium 200 [nm] Back contact 355 nm 532 nm 1064 nm 23

LASER LAB SET UP Manufacturer Modell Helios GN Innolight Helios UV Wavelength [nm] 532 355 Power [W] 3 0,4 Beam Quality M 2 [-] < 1.25 < 1.25 Pulse duration [ns] <0,69 < 0,69 24

LASER PATTERNING P1 P2 P3 50 µm 50 µm 50 µm GEN1 Laser processing P1, P2 and P3 Suitable laser sources identified Test modules in lab produced ITO ʎ = 532 nm; tp < 0,5 ns P3HT:PCBM+PEDOT:PSS ʎ = 355 nm; tp < 0,5 ns Aluminium ʎ = 532 nm; tp < 0,5 ns P1 P2 P3 50 µm 50 µm PEDOT:PSS ʎ = 532 nm; tp < 0,5 ns P3HT:PCBM ʎ = 532 nm; tp < 0,5 ns 50 µm Aluminium ʎ = 532 nm; tp < 0,5 ns GEN2 Processing alternative material systems (ITO free) All patterning steps with one laser Test modules in lab produced 25

TEST MODULES QUALIFICATION 50 mm x 50 mm solar modules on PET foil and glass substrate 8 cells Reached efficiencies in test modules Description sample Moduleffizienz (%) Complete laser structured module on Glas 1.51 Partially laser structured module (except for P3) on PET foil Partially laser structured module (except for P3) on PET foil with PCDTBT absorber layer ITO-free complete laser structured module on PET foil with P3HT absorber layer 1.67 3.05 0.5 ELI & Lock-in Thermography of Solarmodul 26

ROLL-TO-ROLL PILOT MACHINE Target Cost effective mass production Process different material systems Combine different laser sources Process under different atmospheres possible Customized laser, scanner and camera system Data pilot machine Full automated laser structuring with pattern detection Band speed up to 180 m/min Maximal foil width 8 Modular coupling design P1 on 2 foil demonstrated 27

ROLL-TO-ROLL PILOT LASER MACHINE 28

REWINDER AND UNWINDER MODULES Rewinder module Band tension & position control with Cleaning unit Unwinder module 29

LASER STRUCTURING MODULE Front view With scanner system Rear view Laser with optics 30

COATING AND DRYING MODULES Dryer unit Coater unit Caoter & Dryer units 31

VISUAL PRESENTATIONS 2CV.6 Silicon Solar cell Improvemnts. Wednesday 26 Sept. 13:30-15:00 2CV.6.24 Black Silicon Solar Cell Processing with High Repetitive Laser Systems Presenter: Dipl.-Ing (FH) Viktor Schütz 3DV.4 Organic-based PV. Thursday 27 Sept. 17:00-18:30 3DV.4.38 Laser structuring of ITO-free organic thin-film solar modules for rollto-roll mass production Presenter: M.Sc. Javier Gonzalez 32

OUTLINE Beam Shaping for efficiency and productivity increase Efficiency increase of mc-silicon solar cell - Reflectivity reduction by laser structuring - Productivity by multiple beam structuring Roll-to-Roll Production of organic Solar modules - Practicable Laser Patterning in OPV - Laser Patterning module SUMMARY 33

SUMMARY Beam shaping: parallelize a process scaling it up Beam shaping: precisely thin film ablation without any pulse overlap Laser texturing with ultrafast lasers: reflectivity reduction for mc-si SC Laser Patterning of organic solar modules on PET without ITO R2R Pilot machine for coating, drying, laser patterning ready for use 34

ACKNOWLEDGEMENT The Photovoltaics Group at the LZH 35

THANK YOU VERY MUCH FOR YOUR ATTENTION. Laser Zentrum Hannover, Germany 28.09.2012

Laser Zentrum Hannover, Germany 28.09.2012

VERÖFFENTLICHUNGEN 2012: Schütz V., Horn A., Nagel H., Stute U., Black silicon solar cell processing with high repetitive laser systems, Proc. 27 th EUPVSEC 2CV.6.24, Germany, Frankfurt (2012) Schütz V., Horn A., and Stute U., High-throughput process parallelization for laser surface modification on Si-Solar cells: determination of the process window, Proc. SPIE Vol. 8244-33, USA, San Francisco, 2012 2011: Haupt O., Schütz V., and Stute U. "Multi-spot laser processing of crystalline solar cells," Proc. SPIE 7921, 79210V, doi:10.1117/12.876102, 2011 2010: Siegel F., Schütz V., Stute U., Kling R. Large-scale riblet surfaces using multi-spot micro machining, Proc. 29 th ICALEO, M305; Anaheim, USA, 2010 Schoonderbeek A., Schütz V., Haupt O., Stute U. Laser processing of thin films for photovoltaic applications, JLMN Vol.5, No.3, DOI:10.2961/jlmn.2010.03.0013, 2010 38

LAY-OUT AND MATERIALS Module lay-out Transmittance of single layers Patterning step P1 P2 Material ITO + PEDOT:PSS High cond. PEDOT:PSS P3HT:PCBM PCDTBT: PCBM Typical thicknesses 125 + 40 [nm] 150 [nm] 200 [nm] 200 [nm] Function Semi-transparent electrode Photoactive-layer P3 Aluminium 200 [nm] Back contact 355 nm 532 nm 1064 nm 39

LASER STRUCTURING OPV P1 P2 P3 Laser processing P1, P2 and P3 Suitable laser sources identified Test modules in lab produced 50 µm 50 µm 50 µm ITO ʎ = 532 nm; tp < 0,5 ns P3HT:PCBM+PEDOT:PSS ʎ = 355 nm; tp < 0,5 ns Aluminium ʎ = 532 nm; tp < 0,5 ns P1 P2 P3 50 µm 50 µm 50 µm Processing alternative material systems (ITO free) All patterning steps with one laser Test modules in lab produced PEDOT:PSS ʎ = 532 nm; tp < 0,5 ns P3HT:PCBM ʎ = 532 nm; tp < 0,5 ns Aluminium ʎ = 532 nm; tp < 0,5 ns 40

TEST MODULES 50 mm x 50 mm solar modules on PET foil and glass substrate 8 cells Reached efficiencies in test modules Description sample Moduleffizienz (%) Complete laser structured module on Glas 1.51 Partially laser structured module (except for P3) on PET foil Partially laser structured module (except for P3) on PET foil with PCDTBT absorber layer ITO-free complete laser structured module on PET foil with P3HT absorber layer 1.67 3.05 0.5 ELI & Lock-in Thermographie von Solarmodul 41

ROLL-TO-ROLL LASER PROCESSING Target Cost effective mass production Process different material systems Combine different laser sources Process under different atmospheres possible Customized laser, scanner and camera system Data pilot machine Full automated laser structuring Band speed up to 180 m/min Maximal foil width 8 Modular coupling design P1 on 2 foil demonstrated 42

ROLL-TO-ROLL PILOT MACHINE Rewinder and unwinder modules Laser unit Band tension and position control Coating and drying unit 43