OPV Stability From Materials to Modules. H.-J. Egelhaaf

Size: px

Start display at page:

Download "OPV Stability From Materials to Modules. H.-J. Egelhaaf"

Shanon Lynch
6 years ago
Views:

1 OPV Stability From Materials to Modules H.-J. Egelhaaf

2 OPV: Advantages Design features: Flexible, thin, light-weight Printable in various widths Low light sensitivity (indoor/outdoor) Off- angle performance Multiple colors: red, green blue Roll-to-roll printed Transparent version Customized voltage

3 Target: Building Integrated Applications Arch Aluminum & Glass Curtain Wall Tamarac, Florida Konarka New Bedford, MA Green House Plants View Bus Shelter San Francisco, CA

4 Requirements for any PV technology Efficiency (%) United Solar UCSB 1995 NREL United Solar University of Lausanne Cambridge 2000 NREL NREL U. Linz NREL NREL Sharp EPFL (SSDSSC) Konarka Heliatek Konarka Solarmer Solarmer UCSB Konarka Plextronics Konark a Siemens Siemens 2005 Year Thin Film Technologies Cu(In,Ga)Se 2 CdS/CdTe a- Si/a-SiGe Emerging PV Dye cells OPV (polymer) OPV single junction 4 0 Efficiency (>3%) Lifetime (3-5 years) Costs (<1 /Wp) Required for Building Integrated Applications: > 6% (module!) A successful product must fulfil all 3 requirements Efficiency, Lifetime and Cost

5 Higher Measured Efficiency in Usage Conditions Normalized Energy (watt hours) Konarka OPV a-si c-si CIGS Competitive Testing - Energy Collection on 08/01/10 Solar Irradiance Panels are Normalized to 5 Watts measured in standard lab conditions Higher efficiency at higher temperatures AM 6 AM 7 AM 8 AM 9 AM 10 AM 11 AM 12 PM 1 PM 2 PM 3 PM 4 PM 5 PM 6 PM 7 PM 8 PM 9 PM 1,400 1,200 1, Solar Irradiance (W/m 2 ) 20-35% more energy collected in one day (with respect to std lab conditions) than competitive PV technologies. Higher Efficiency at Low Light

6 Requirements for any PV technology Lifetime (3-5 years) Efficiency (>3%) Costs (<1 /Wp) Building Integrated Applications: < 1 /Wp (module) A successful product must fulfil all 3 requirements Efficiency, Lifetime and Cost

7 Requirements for any PV technology Lifetime (3-5 years) Efficiency (>3%) Costs (<1 /Wp) Flex Applications (niche markets?): > 5 years Building Integrated Applications: > 15 years in 2011 > 20 years in 2012 A successful product must fulfil all 3 requirements Efficiency, Cost and Lifetime

8 Overview of Degradation Mechanisms

9 Towards 20 Years Lifetime The complexity of the problem requires breaking down the task into three levels: - Materials (Degradation of Organic and Inorganic Components) - Solar Cells (Decay of Performance) - Solar Modules (Cells + Buss Bars + Packaging + Electrical Connections)

10 Materials Understanding the degradation mechanisms will help make OPV intrinsically more stable Longer life times Save on costs for packaging Degradation of the polymer depends on: - the chemical structure of the polymer - the environmental conditions - the composition of the photoactive blend

11 Photo-oxidation oxidation of P3HT: wavelength Reaction Spectra Absorbance Regio-random P3HT 1,5 1,0 0,5 b Absorption Regio-regular P3HT Action Spectra Effectiveness 0,0 1E-5 1E-6 1E Wavelength λ [nm] E Irradiation Wavelength [nm] Effectiveness 1E Wavelength λ[nm] E E Irradiation wavelength / nm 800 The PCQY does not follow the absorption spectrum radical mechanism very probable H. Hintz, H.-J. Egelhaaf, L. Lüer, J. Hauch, H. Peisert, Th. Chassé, Chem. Mater. 23 (2011) 145

12 Photo-oxidation oxidation of P3HT: wavelength λ irr = 365 nm FTIR signals λ irr = 525 nm Abs normalized 1.0 UV 365 a Time*10 3 [min] S n Abs normalized b VIS Time*10 3 [min] Absorbance [norm] UV 365 a UV/VIS loss at 520 nm [norm] S n Absorbance [norm] VIS 525 b UV/VIS loss at 520nm [norm] Different reaction pathways for different wavelengths H. Hintz, C. Sessler, H. Peisert, T. Chassé, H.-J. Egelhaaf, in preparation

13 Photo-oxidation oxidation of P3HT: Humidity Time trace of absorption maximum during degradation under 1: oxygen 2: humidified oxygen (100% rel. Humidity) 3: humidified nitrogen (100% rel. Humidity) Absorbance 0,6 0,4 0,2 0, time / min a reaction rate / 10-3 min b Relative humidity % at 22 C reaction rate % H. Hintz, H.-J. Egelhaaf, L. Lüer, J. Hauch, H. Peisert, Th. Chassé, Chem. Mater. 23 (2011) 145

14 Effect of Fullerene Structure E Fullerene LUMO energy F1 (-3.53 ev) LUMO e - F2 (-3.60 ev) e - LUMO F3 (-3.66 ev) F4 (-3.70 ev) PCBM hν HOMO F5 (-3.75 ev) P3HT Fullerene F6 (-3.80 ev) F7 (-3.81 ev) F8 (-3.83 ev)

15 Effect of Fullerene on P3HT Photobleaching normalized OD at P3HT maximum [%] 99 Fullerene (LUMO): F1 (-3.53 ev) 88 F2 (-3.60 ev) 77 F3 (-3.66 ev) F4 (-3.70 ev) 66 F5 (-3.75 ev) 55 F6 (-3.80 ev) F7 (-3.81 ev) 44 F8 (-3.83 ev) time of degradation [h] All fullerenes stabilize P3HT Stabilizing factor: 2-7 (5 for PCBM) A. Distler, H.-J. Egelhaaf, D. Waller, K.-S. Cheon, S. Rodman, D. Guldi, in preparation pristine P3HT

16 Photobleaching vs. Fullerene LUMO normalized OD at P3HT maximum [%] LUMO [ev] time of degradation: 0 h 0.5 h 1 h 2 h 3 h 5 h 10 h 30 h 50 h maximum stabilization effect (F5)

Effect of Polymer Structure / Fullerene Fluorescence Intensity and Degradation Rate as a Function of PCBM content 2.0 1.5 1.0 0.

17 Effect of Polymer Structure / Fullerene Fluorescence Intensity and Degradation Rate as a Function of PCBM content a) C-PCPDTBT D/D0 Degradation D/D0 rate+ DIO F/F0 Fluorescence F/F0 intensity + DIO PCBM enhances degradation b) P3HT D/D0 F/F0 S PCBM reduces degradation c) Si-PCPDTBT D/D Degradation D/D0 + DIO rate F/F Fluorescence F/F0 + DIOintensity x PCBM (w/w) n PCBM slightly reduces degradation P. Kutka, A. Distler, T. Sauermann, H.-J. Egelhaaf, D. Di Nuzzo, S.C.J. Meskers, R.A.J. Janssen, in preparation

18 Solar Cells Degradation by Light and Oxygen air N 2 Overall Loss of Efficiency consists of reversible and irreversible component

Irreversible Component 1.5 Absorption and J sc Loss after Illumination in Synthetic Air and Annealing in Nitrogen 1.0 O.D. 0.5 0% 2% 5% 10% 20% Current density / ma*cm -2 0.

19 Irreversible Component 1.5 Absorption and J sc Loss after Illumination in Synthetic Air and Annealing in Nitrogen 1.0 O.D % 2% 5% 10% 20% Current density / ma*cm Wavelength (nm) b undegraded 2% degraded 5% degraded Voltage / V Minor Changes in Absorption lead to 50% J sc Loss

20 Irreversible Degradation Leads to Strong Photoluminescence Quenching Photoluminescence (10 6 counts) Absorption loss [%] PL loss [%] % 2% 5% 10% 20% + P3HT - PCBM Wavelength (nm) Loss in excitons which recombine in the P3HT domains! What about all the other excitons?

21 Effect of Degradation on Excited States - Strong effect of degradation products on excitons (ExA) on a very short timescale - Polaron (DP) lifetime slightly decreases with degradation due to recombination via degradation products (a) (b) (d) (c) Energy LUMO τ HEx-Ext τ Exd-Polt τ HEx-Polf τ Polf-r HOMO P3HT PCBM Transients at Different Degrees of Bleaching T/T (10-2 ) T/T (10-2 ) (a) (c) 0% (b) ExA DP 0% 10% 20% Time Delay (ps) (d) 10% 20% Time Delay (ps) F. Deschler, A. De Sio, E. von Hauff, P. Kutka, T. Sauermann, H.-J. Egelhaaf, J. Hauch, E. Da Como, Adv. Funct. Mater., accepted

22 Reversible Oxygen Effect on jv-curves Solar Cell with inverted structure and Ag grid electrode Reversible oxygen doping leads to reduction of j sc A. Seemann, T. Sauermann, C. Lungenschmied, O. Armbruster, S. Bauer, H.-J. Egelhaaf, J. Hauch, Solar Energy 85 (2011) 1238

and to loss in FF (irreversible) A. Seemann, T. Sauermann, C.

23 Temporal behaviour of cell performance Cell parameters: efficiency, j sc, V oc, FF Performance loss is mainly due to loss in j sc (partly reversible) and to loss in FF (irreversible) A. Seemann, T. Sauermann, C. Lungenschmied, O. Armbruster, S. Bauer, H.-J. Egelhaaf, J. Hauch, Solar Energy 85 (2011) 1238

dark - accelerated under illumination A. Seemann, T. Sauermann, C.

24 Oxygen Effect on CELIV measurements CELIV traces Charge carrier concentration Oxygen doping leads to increase in charge carrier concentration - Slow in the dark - accelerated under illumination A. Seemann, T. Sauermann, C. Lungenschmied, O. Armbruster, S. Bauer, H.-J. Egelhaaf, J. Hauch, Solar Energy 85 (2011) 1238

25 Charge Carrier Formation Monitored by ESR ESR signal in the dark and under illumination Time trace of ESR signal upon light on under air and light off under vacum Light + Oxygen Formation of Metastable Charge Carriers A. Aguirre, S.C.J. Meskers, R.A.J. Janssen, H.-J. Egelhaaf, Org. Electronics (2011)

26 Mechanism of Oxygen Doping E / ev hν P3HT O 2 PCBM

27 Effect on Device: Simulation with PC1D Solving the fully coupled set of Differential Equations for an Effective Medium Bulk Semiconductor Doping leads to the formation of a space charge region in front of the anode Shielding of the electric field in the bulk Reduced charge carrier extraction

28 Modules Intrinsic Degradation Active layers Interfaces Electrodes Lifetime is a System Property Extrinsic Degradation BussBars, Leads Packaging films Adhesives

29 Outdoor Testing - Konarka Lowell, MA Location Lowell, MA. facing solar south at kwh / m2 2 measurement modes: a) Outdoor JV in 4th quadrant with modulated load and wireless data read out b) Periodic characterization under standard solar simulator Southern Florida Southern Arizona

30 Encapsulation of the Module Buss Bar Electrode Active Layers Encapsulation Substrate

31 affords Outdoor LT > 2yrs Normalized Efficiency 140% 120% 100% 80% 60% 40% 20% 0% Gen1, Lowell Rooftop Gen 2, Lowell rooftop Gen2, South Florida Two years outdoor without drop in performance.

32 Accelerated Lifetime Testing Stress Factors Light Humidity Temperature Oxygen Hot/Cold cycles Wet/Dry cycles Wind Rain Hail Pollutants Intrinsic Degradation Active layers Interfaces Electrodes Lifetime is a System Property Extrinsic Degradation BussBars, Leads Packaging films Adhesives

33 Standard ALT Testing Equipment Test Equipment Solar Simulator AM1.5G, 100 mw/cm 2 Dry Ovens Pass 1000 hrs at 65 C Steady State Oven Temperature / Humidity Thermal Cycling Chamber Temperature Light Soaking / Humidity Chambers Temperature / Humidity / Rain Ultraviolet Flex bending Light Chamber Pass C / 85 % r.h. (extended 3 hrs cycle, 85 C/85-40 C to % + r.h.) 80 C Pass 1000 hrs 65 C/1sun According to IEC + IEEE + ASTM standards > 1000 bends over 50 mm roll

34 Lifetime of Production Modules Norm. Eff. [a.u.] C/1sun Time [hours] Building a correlationwithoutdoorlifetimedata.

35 Lifetime of Production Modules WVTR Barrier1 >> WVTR Barrier2 >> WVTR Barrier3 Norm. Eff. [a.u.] C/85%rh Barrier 3 Barrier 1 Barrier Time Hours Lifetime of the modules depends on the adhesive/barrier quality.

36 Flex Product pre-qualification for letter of compliance IEC damp heat 85 C/85%RH 1000hours PAS SED

37 Flex Product pre-qualification for letter of compliance IEC thermal cycling (50 cycles) + IEC humidity freeze (10 cycles) PASSED

38 Acknowledgments The German Ministry for Education and Research is Acknowledged for Funding (BMBF project OPV Stability )

Product Development for Organic Photovoltaics

Product Development for Organic Photovoltaics Jens Hauch jhauch@konarka.com Who is Konarka? Renewable Energy Printable low-cost Solar Cell Organic Chemistry Printed Electronics Innovators at the Intersections