Presentation is loading. Please wait.

Presentation is loading. Please wait.

IMPROVING EFFICIENCY OF ORGANIC PHOTOVOLTAICS 11/08/12 Nanjia Zhou Northwestern University.

Similar presentations


Presentation on theme: "IMPROVING EFFICIENCY OF ORGANIC PHOTOVOLTAICS 11/08/12 Nanjia Zhou Northwestern University."— Presentation transcript:

1 IMPROVING EFFICIENCY OF ORGANIC PHOTOVOLTAICS 11/08/12 Nanjia Zhou Northwestern University

2 http://econews.com.au/news-to-sustain-our-world/un-takes-hard-look-at- 20-years-since-rio-earth-summit/ http://planetark.org/enviro-news/item/53111 http://thecityfix.com/blog/choking-on-smog/ Nanjia Zhou Chang/Marks Group 1 1

3 International Energy Outlook 2011 Nanjia Zhou Chang/Marks Group 2 2

4 International Energy Outlook 201103/23/2012 3 3

5 Department of Materials Science03/23/2012 Photo courtesy: NREL Clean, renewable Reduced dependence on Fossil Fuels Distributed generation Proven, reliable Modularity and Scalability 4 4

6 http://www.heliatek.com/technologie/organische- photovoltaik/?lang=en Photo courtesy: NREL Nanjia Zhou Chang/Marks Group 5 5

7 National Renewable Energy Laboratory (NREL) Photo courtesy: NREL Nanjia Zhou Chang/Marks Group 6 6

8 Photo courtesy: NREL Mitsubishi Chemical announced a certified 10.0% cell National Renewable Energy Laboratory (NREL) Nanjia Zhou Chang/Marks Group 7 7

9 Photo courtesy: NREL Nanjia Zhou Chang/Marks Group 8 8

10 Department of Materials Science03/23/2012 Photo courtesy: NREL 9 9

11 http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2 000/press.html Photo courtesy: NREL Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa "for the discovery and development of conductive polymers". The Nobel Prize in Chemistry 2000 Nanjia Zhou Chang/Marks Group 1010 1010

12 Common conducting polymers Soliton Polaron Bipolaron Nanjia Zhou Chang/Marks Group 11

13 Gate Insulating layer Organic layer SourceDrain +++++++++++++++++++ -30V ------------------- ++++++++++++++ 1. Organic Field Effect Transistor (OFET) Nanjia Zhou Chang/Marks Group 1212 1212

14 1. OFET Nanjia Zhou Chang/Marks Group 1313 1313

15 Photo courtesy: NREL 1. OFET Nanjia Zhou Chang/Marks Group 1414 1414

16 2. Organic Light Emitting Diode (OLED) 07080910 2.0 , 2.2 , 2.4 , 2.6’’ QVGA 2.5’’ QVGA(Landscape) 2.6 , 2.8 , 3.0’’ LQVGA 3.1’’ WVGA 4.1’’ WQVGA 3.5’’ WQVGA*3D 4.8’’ WVGA 7.0’’ WSVGA 14-15.4’’ WXGA 21-23’’ UXGA 40’’/42’’ Full HD Nanjia Zhou Chang/Marks Group 1515 1515

17 2. OLED 1. Brighter, thinner, lighter, faster 2. Bright from all viewing angles 3. Need less power to run 4. A lot cheaper to produce 5. Expanding memory capability - coating new layer on top of existing one 6. Wider temperature range OLED is a display device that sandwiches carbon based films between the two electrodes and when voltage is applied creates light. Nanjia Zhou Chang/Marks Group 1616 1616

18 2. OLED Nanjia Zhou Chang/Marks Group 1717 1717

19 3. OPV Nanjia Zhou Chang/Marks Group 1818 1818

20 3. OPV Nanjia Zhou Chang/Marks Group Holger Spanggaard, Frederik C. Krebs, Solar Energy Materials and Solar Cells, Volume 83, Issues 2–3, 15 June 2004, Pages 125-146 1919 1919

21 Harvard Science in the News: https://sitn.hms.harvard.edu/sitnflash_wp/2012/03/issue113/ Photo courtesy: NREL OPV vs. Silicon Cell Nanjia Zhou Chang/Marks Group 2020 2020

22 Narrower absorption range than silicon cell Lower current output Donor: Electron rich material Acceptor: Electron poor material Bulk Heterojunction: Blend of D/A materials forming a heterogeneous mixture Domain size OPV vs. Silicon Cell Nanjia Zhou Chang/Marks Group Li et al. Nature Photonics 6, 153–161, (2012) 2121 2121

23 Kietzke, Advances in OptoElectronics Volume 2007 (2007), Article ID 40285 a.Short circuit b.Open circuit c.Forward bias d.Reverse bias Characterization Nanjia Zhou Chang/Marks Group 22

24 Class A Solar Cell Analyzer –AM 1.5G simulated light –Scan area: 5 x 5 cm –Light and dark evaluation –Series resistance evaluation –Xenon lamp with an adjustable intensity of 850 - 1150 W/m 2 –Calibrated with KG3-filtered Si standard from NREL. Spectral mismatch = 1.00 Spectral Response –Examines wavelengths from 400 - 1100 nm –Includes 15 filters in this range Circulating Bath –Cell test temperature variable from - 15C to +75C NU Characterization Nanjia Zhou Chang/Marks Group 2323 2323

25 ORGANIC PHOTOVOLTAICS Cathode – Conventional cell Low work function metal: Ca/Al (Anode – Inverted Cell High work function metal: Ag/Au) Cathode IFL – LiF, n-type semiconductors: ZnO, TiO 2 Active Layer: blend of donor and acceptor materials Transparent conductive substrate – ITO, Carbon based material Anode IFL: PEDOT:PSS P-type semiconductor: NiO, WO 3, MoO 3, V 2 O 5 graphene oxide Nanjia Zhou Chang/Marks Group 2424 2424

26 Nanjia Zhou Chang/Marks Group ORGANIC PHOTOVOLTAICS μ ED μ CT μ CC 2525 2525

27 Nanjia Zhou Chang/Marks Group ORGANIC PHOTOVOLTAICS Band Gap Tuning: Lower band gap to raise J sc. Higher IP polymers and lower EA acceptors to reduce energy loss during charge separation. STRATEGIES FOR EFFICIENCY ENHANCEMENT Decrease LUMO- LUMO offset Morphology Control: Domain sizes comparable to exciton diffusion length Efficient carrier transport Experimentally: solvent, additive, processing conditions, and self organizing properties of materials Photon Management: Alter device architecture to focus photo absorption in active layer Potentially reduce active layer thickness for higher IQE Ordered Heterojunction: Donor/acceptor form interdigitated morphology within nanometer scale Direct pathways of donor/acceptor to electrodes Nelson, J. Materials Today 2011, 14, 462–470. Li, G.; Zhu, R.; Yang, Y. 2012, 1–9. Kang, M.-G.; Xu, T.; Park, H. J.; Luo, X.; Guo, L. J. Adv. Mater. 2010, 22, 4378. 2626 2626

28 RESEARCH OUTLINE Novel high efficiency donor- type polymers, study of device characteristics Materials Development Nanoscale patterning of polymer active layer surface. Photonic and plasmonic enhancement of photocurrent Plasmonic Structure Tandem device to enhance light harvesting; Optimize electron/hole transport Nanowire, Tandem, Hybrid, etc. Nanjia Zhou Chang/Marks Group Band Gap Tuning Photon Management Novel Device Architecture Processing conditions; Solvent choice; Polymer stacking; Characterization Morphology-Carrier Transport Relationship Morphology Control 2727 2727

29 Nanjia Zhou Chang/Marks Group Control of nanoscale morphology: Domain size variation Morphology Carrier Transport Relationship

30 Nanjia Zhou Chang/Marks Group BILAYER VS. BHJ 2828 2828

31 Nanjia Zhou Chang/Marks Group EFFECT OF PROCESSING CONDITIONS 2929 2929 Annealing Treat, N. D., Brady, M. A., Smith, G., Toney, M. F., Kramer, E. J., Hawker, C. J. and Chabinyc, M. L. (2011), Interdiffusion of PCBM and P3HT Reveals Miscibility in a Photovoltaically Active Blend. Adv. Energy Mater., 1: 82–89. doi: 10.1002/aenm.201000023

32 Nanjia Zhou Chang/Marks Group EFFECT OF PROCESSING CONDITIONS 3030 3030 Solvent choice Lee et al. J. Am. Chem. Soc. 130, 3619 (2008)

33 Nanjia Zhou Chang/Marks Group CRYSTALLINITY AND PACKING 3131 3131 Huang et al. J. Phys. Chem. C, 2012, 116 (18), pp 10238–10244

34 Nanjia Zhou Chang/Marks Group CHARACTERIZATION 3232 3232 Lu et al. Nature Communications 3, Article number: 795 Atomic Force Microscope (AFM), Transmission Electron Microscope (TEM) Grazing Incidence Wide Angle X-ray Scattering (GIWAXS)

35 33 Increase DIO concentration Nanjia Zhou Chang/Marks Group PC 71 BMBTIBDT High sensitivity of DIO 0 0.5%1.0%3.0%10.0% N. Zhou, A. Guerrero, H. Heitzer, S. Lou et. al. PRECISE MANIPULATION OF DOMAIN SIZES

36 High Performance Donor Materials Nanjia Zhou Chang/Marks Group

37 Nanjia Zhou Chang/Marks Group Li et al. Nature Photonics 6, 153–161, (2012) 3434 3434

38 Nanjia Zhou Chang/Marks Group Zhou et al. Adv. Mater., 24: 2242–2248 1)R 1 =2-hexyldecyl, R 2 =2-ethylhexyl; PCE=3.4% 2)R 1 =2-butyloctyl, R 2 =2-ethylhexyl; PCE=4.8% 3)R 1 =2-hexyldecyl, R 2 =n-dodecyl; PCE=5.5% 4)R 1 =2-butyloctyl, R 2 =n-decyl; PCE=3.3% 5)R 1 =n-octyl, R 2 =2-butyloctyl; PCE=1.6% BTIBDT BASED COPOLYMERS 3535 3535

39 Bithiophene Imide (BTI) and Benzodithiophene (BDT) Copolymers Inverted OPVs The electron deficiency of the BTI units leads to polymers with a low-lying HOMOs (~-5.6 eV). Inverted solar cells are fabricated to investigate the OPV performance of the BTI- based polymers and achieve power conversion efficiencies up to 5.5%, with substantial V oc s above 0.9 V which are among the highest V oc s reported to date for polymer/PCBM solar cells. Nanjia Zhou Chang/Marks Group Zhou et al. Adv. Mater., 24: 2242–2248 3636 3636

40 Bithiophene Imide (BTI) and Benzodithiophene (BDT) Copolymers Inverted OPVs Nanjia Zhou Chang/Marks Group BTIBDT BASED COPOLYMERS Inverted architectures: ITO/ZnO/polymer:PC 71 BM/MoOx/Ag Inverted structures avoid oxidation of low work- function cathodes, such as Al or Ca, and acidic PEDOT:PSS etching of ITO, both of which limit conventional devices. ZnO is an excellent cathode interfacial layer due to its high electron mobility, excellent thermal stability, and hole-blocking properties. MoOx conduction band (-2.60 eV) lies sufficiently above the donor LUMOs (-3.7 eV, estimated from the HOMOs and optical band gaps), to block electrons, while the low work function (-5.6 eV) forms a good anode contact with the donor polymers Zhou et al. Adv. Mater., 24: 2242–2248 3737 3737

41 Polymer:PC 71 BMSolventThickness (nm)V oc (V)J sc (mA/cm 2 )FF (%)PCE (%) P11:1.5DCB950.9924.1647.91.98 P21:1DCB1000.9404.7656.32.52 P11:1.5DCB+DIO a 950.8769.6951.84.39 P21:1DCB+DIO a 1000.9229.6262.05.50 J-V CurveEQE and UV-vis Stability Device Performance Nanjia Zhou Chang/Marks Group BTIBDT BASED COPOLYMERS Stability Best device achieved without thermal annealing Initial drop due to microstructural reorganization Zhou et al. Adv. Mater., 24: 2242–2248 3838 3838

42 Nanjia Zhou Chang/Marks Group BTIBDT BASED COPOLYMERS Conventional Device and SCLC measurement Polymer:PC 71 BMV oc [V]J sc [mA/cm 2 ]FF (%)PCE (%) P11:1.50.8727.8751.13.51 P21:10.9058.0655.14.02 Space charged limited current (SCLC) measurement ITO/PEDOT:PSS/polymer/Au Hole mobilities OTFT: 1.2 × 10 -4 and 2.8 × 10 -4 cm 2 V -1 s -1 SCLC: 5.5 × 10 -5 and 1.9 × 10 -4 cm 2 V -1 s -1 for P1 and P2-based OTFTs and hole only devices, respectively Conventional Device Performance Zhou et al. Adv. Mater., 24: 2242–2248 3939 3939

43 Without DIO, predominantly phase-segregated morphologies for the P1/PC 71 BM and P2/PC 71 BM blends. The dark regions in the TEM images confirm large PC 71 BM domain sizes -- far larger than typical exciton diffusion lengths (~10 nm). Consequently, poor exciton dissociation and low current density are expected. Significantly more homogeneous morphologies are found for P1/PC 71 BM and P2/PC 71 BM films processed with DIO. nanosacle phase separation and bicontinuous interpenetrating networks result in more efficient charge separation and transport, leading to more than doubled J sc. Nanjia Zhou Chang/Marks Group BTIBDT BASED COPOLYMERS Morphology Optimization 4040 4040 Zhou et al. Adv. Mater., 24: 2242–2248

44 BTI and Dithienosilole (DTS) Copolymers Inverted OPVs Nanjia Zhou Chang/Marks Group BTIDTS BASED COPOLYMERS 4141 4141 Polymer DCB:DIO (%:%) V oc (V) J sc (mA/cm 2 ) FF (%) PCE (%) P1100:00.8386.0652.62.67 P198:20.83412.5153.15.54 P2100:00.8476.4648.42.65 P298:20.80312.8162.36.41 X. Guo, N. Zhou, et al. JACS (2012)

45 Nanjia Zhou Chang/Marks Group BTI BASED COPOLYMERS X. Guo, N. Zhou, et al. JACS (2012) 4242 4242

46 Nanjia Zhou Chang/Marks Group BTI BASED COPOLYMERS X. Guo, N. Zhou, et al. JACS (2012) 4343 4343

47 44 Nanjia Zhou Chang/Marks Group BTI BASED COPOLYMERS X. Guo, N. Zhou, et al. JACS (2012)

48 4545 4545 Nanjia Zhou Chang/Marks Group BTIDTG COPOLYMERS Polymer% of DIO additivesV oc (V)J sc (mA/cm 2 )FF (%)PCE (%) PBTISi-C62.00.82412.5960.66.29 PBTISi-C82.00.80312.8162.36.41 PBTISi-EH2.00.79112.4956.45.57 PBTIGe-C63.00.77011.7647.24.27 X. Guo, N. Zhou, et al. JACS (2012)

49 Nanjia Zhou Chang/Marks Group BTI/TPD-DTS COPOLYMERS X. Guo, N. Zhou, et al. JACS (2012) 4646 4646

50 Nanjia Zhou Chang/Marks Group neat polymer polymer/PC 71 BM DCB:DIO=100:0 polymer/PC 71 BM DCB:DIO=98:2 BTIDTS BASED COPOLYMERS BTI and Dithienosilole (DTS) Copolymers Inverted OPVs P1 P2 π-π stacking distances are 3.6 Å and 3.5 Å for P1 and P2, respectively X. Guo, N. Zhou, et al. JACS (2012) 4848 4848

51 Nanjia Zhou Chang/Marks Group BTIDTS BASED COPOLYMERS X. Guo, N. Zhou, et al. JACS (2012) 4949 4949

52 Nanjia Zhou Chang/Marks Group 5050 5050 BTIDTS MORPHOLOGY TEM images of PBTISi-C8 with different D/A ratio: (a) P:PC 71 BM (1:1), (b) P:PC 71 BM (1:1.5), and (c) P:PC 71 BM (1:2) blend films processed in DCB as solvent with 2% DIO. X. Guo, N. Zhou, et al. JACS (2012)

53 Nanjia Zhou Chang/Marks Group 5151 5151 BTIDTG COPOLYMERS X. Guo, N. Zhou, et al. JACS (2012)

54 Nanjia Zhou Chang/Marks Group 5252 5252 HiGH FF OPV AND MORPHOLOGY STUDY X. Guo, N. Zhou, et al. Nature Photonics (2012)

55 Nanjia Zhou Chang/Marks Group 5353 5353 HiGH FF OPV AND MORPHOLOGY STUDY X. Guo, N. Zhou, et al. Nature Photonics (2012)

56 Nanjia Zhou Chang/Marks Group 5454 5454 HiGH FF OPV AND MORPHOLOGY STUDY X. Guo, N. Zhou, et al. Nature Photonics (2012)

57 Nanjia Zhou Chang/Marks Group 55 HiGH FF OPV AND MORPHOLOGY STUDY X. Guo, N. Zhou, et al. Nature Photonics (2012)

58 Nanjia Zhou Chang/Marks Group Nanoscale patterning of polymer active layer surface. Photonic and plasmonic enhancement of photocurrent Photon Management

59 Nanjia Zhou Chang/Marks Group 5656 5656 PLASMONIC OPV Enhancement at Front electrode M. Heo, H. Cho, J. Jung, J. Jeong, S. Park, J. Kim, Adv. Mater. 2011, 23, 5689 M. Kang, T. Xu, H. Park, X. Luo, L.J. Guo Adv. Mater. 2010, 22, 4378 J. Yang, J. You, C. Chen, W. Hsu, H. Tan, X. Zhang, Z. Hong, Y. Yang ACS Nano 2011 5 (8), 6210 Device Fabrication Ag nanowire grating as electrode blending Au nanoparticle into interfacial layer metallic nanoparticles at front electrode

60 Nanjia Zhou Chang/Marks Group 5757 5757 PLASMONIC OPV Device Fabrication Lower transmission at TCO Reducing conductivity of TCO Disrupting organic/inorganic interface at TCO Affecting film quality and possibly polymer packing Introducing extra step that cannot be easily incorporated into fabrication, thus affect reproducibility. Modifying Front Electrode Modifying Rear Electrode No effect on device fabrication prior to metal evaporation Easily convert the metallic electrode into a plasmonic grating. The grating can increase the amount of light trapped in the active layer through three potential pathways. Trap the light in the form of surface plasmon polaritons (SPP). Increase the surface area of the interface. Increase the diffraction of light.

61 5858 5858 Nanjia Zhou Chang/Marks Group PLASMONIC OPV Collaboration with S. Lubin (Odom group), A. Hryn (Odom group) Device Fabrication N. Zhou, S. Lubin, A. Hryn, X. Guo et. al. Manuscript in preparation ITO ZnO Active Layer MoO x Ag ITOZnO solution processing Active layerHot embossing Thermal evaporation of rear electrode

62 5959 5959 Nanjia Zhou Chang/Marks Group PLASMONIC OPV Collaboration with S. Lubin (Odom group), A. Hryn (Odom group) DeviceV oc [V]J sc [mA/cm 2 ]FF (%)PCE (%) Plasmonic0.58011.564.04.28 No plasmonic0.5829.3868.53.74 Device Performance N. Zhou, S. Lubin, A. Hryn, X. Guo et. al. Manuscript in preparation Plasmonic0.56512.856.24.07 Sq 600 nm Sq 400 nm

63 Nanjia Zhou Chang/Marks Group Tandem device to enhance light harvesting; Optimize electron/hole transport Novel Device Architectures

64 Nanjia Zhou Chang/Marks Group 6060 6060 Yang Yang et al. Nature Photonics, 6, 2012, 180 TANDEM SOLAR CELLS

65 Nanjia Zhou Chang/Marks Group 6161 6161 TANDEM SOLAR CELLS The maximum efficiency for a two junction tandem under the AM1.5G spectrum and without concentration is 47 %. At the peak efficiency the top cell has a bandgap of 1.63 eV and the bottom cell has a bandgap of 0.96 eV.

66 Nanjia Zhou Chang/Marks Group 6262 6262 PCE greater than 40% is the highest efficiency obtained to date for triple junction inorganic photovoltaic cells. TANDEM SOLAR CELLS

67 Nanjia Zhou Chang/Marks Group 6363 6363 P3HTPSBTBT TANDEM ORGANICS SOLAR CELLS Jin Young Kim, Kwanghee Lee, Nelson E. Coates, Daniel Moses, Thuc- Quyen Nguyen, Mark Dante, and Alan J. Heeger Science 13 July 2007: 317 (5835), 222-225.

68 Nanjia Zhou Chang/Marks Group 6464 6464 Dresden, Germany-based OPV thin-film developer Heliatek has achieved a new organic tandem solar cell world record with 10.7% cell efficiency on a 1.1cm 2 substrate. “Deposition of small organic molecules in a low temperature, roll-to-roll vacuum process” TANDEM ORGANICS SOLAR CELLS Yang Yang group, UCLA reaches 10.6% efficiency a world’s first for polymer organic photovoltaic devices “Their tandem structure consists of a front cell with a larger (or high) band gap material and a rear cell with a smaller (or low) band gap polymer, connected by a designed interlayer.” Sumitomo's low–band gap polymer

69 Nanjia Zhou Chang/Marks Group 6565 6565 INTERLAYER Metal ohmic contacts with sub-cells Ag, Au: Yakimov et al. (2002) Colsmann et al. (2006) used n-doped and p-doped organic layers on either side of a thin Au layer as hole blocking and electron blocking layer, respectively. first time reaches nearly additive V oc =1 V p-type layer: high work function metal oxides such as molybdenum oxide (MoO 3 ) or tungsten oxide (WO 3 ), PEDOT:PSS n-type layer: solution-processed ZnO and TiO 2 A. Yakimov and S. R. Forrest, Appl. Phys. Lett., 2002, 80, 1667. A. Colsmann, J. Junge, C. Kayser and U. Lemmer, Appl. Phys. Lett., 2006, 89, 203506.

70 Nanjia Zhou Chang/Marks Group 66 PROCESSING Sustain the solution process of the top polymer layer and protect the bottom polymer layer deposited ITO or thermally evaporated semitransparent metal layers such as Au An n-type layer using ZnO or TiO 2 is coated from an alcohol based solvent aqueous based PEDOT:PSS Difficult to find a solvent for the top polymer layer that does not dissolve the bottom polymer layer. (high boiling point solvents for the top polymer layer may be detrimental to the integrity of underlying layers) Wettability of interlayer and top cells Modified PEDOT:PSS layer (dilute by alcohol, add surfactant) Thin layer of metal

71 Nanjia Zhou Chang/Marks Group 6767 6767 Yang Yang et al. Nature Photonics, 6, 2012, 180

72 Nanjia Zhou Chang/Marks Group 6868 6868 N. Zhou, et al. Manuscript in preparation

73 Nanjia Zhou Chang/Marks Group ITO NANOWIRE ELECTRODE 6969 6969 N. Zhou, et al. Manuscript in preparation ITO IFL by ALD Vertically grown ITO nanowire on ITO substrate Filled with active layer Vertically grown ITO nanowire on ITO substrate Surface modification SAM growth Active layer filling Electrode deposition Inefficiency of hole transport due to relatively poor hole mobility of polymer semiconductor comparing to the electron mobility of PCBM Reduce hole transport distance Greatly enhance electrode (anode) surface area Potentially increase hole transport and hole collection efficiencies Li, S. Q.; Guo, P.; Zhang, L.; Zhou, W.; Odom, T. W.; Seideman, T.; Ketterson, J. B.; Chang, R. P. H. ACS Nano 2011, 5, 9161–9170.

74 Nanjia Zhou Chang/Marks Group ITO NANOWIRE ELECTRODE 7070 7070 N. Zhou, P. Guo, S. Li, et. al. Facilitate hole transport Current fabricated device structure Proposed device structure

75 Nanjia Zhou Chang/Marks Group SUMMARY AND OUTLOOK Morphology control Manipulation of domain (PCBM cluster) size Processing conditions Characterization of domain size Relate to J-V parameters Photon management A simple method through hot embossing Convert the standard Ag electrode >20% increase in Jsc Novel Device Architectures Tandem OPVs Facilitate carrier transport/reduce bimolecular recombination probability Active layer filtration through solution processing/surface functionalization Further optimize processing conditions to create interdigitated structure Materials development BTI-BDT demonstrated one of the highest Voc BTI-DTS achieved performance of 6.4% Highest performance in literatures: 8.7%

76 Nanjia Zhou Chang/Marks Group ACKNOWLEDGEMENT Advisers: Prof. Tobin Marks Prof. RPH Chang Prof. Antonio Facchetti Marks group Dr. Xugang Guo Mimi Lou Stephen Loser Chang group: Dr. D. B. Buchholz Shiqiang Li Peijun Guo Marks B team members Committee Members: Prof. Lin Chen Prof. Mark Hersam Collaborators: Dr. Antonio Guerrero, Prof. Juan Bisquert group, Spain Steven Lubin and Alex Hryn, Prof. Teri Odom group

77 Thank you! “The Apollo Projects Of Our Time” - Steven Chu Courtesy of Backwoods Solar Electric Systems & NREL


Download ppt "IMPROVING EFFICIENCY OF ORGANIC PHOTOVOLTAICS 11/08/12 Nanjia Zhou Northwestern University."

Similar presentations


Ads by Google