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Fabrication of Organic bulk Heterojunction Solar Cell

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Fabrication of Organic bulk Heterojunction Solar Cell

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Fabrication of Organic bulk Heterojunction Solar Cell

  1. 1. Fabrication of Organic bulk Heterojunction Solar Cell Professor: Dr.Joodaki Presented by: Farzane Senobari Fall 2016
  2. 2. 2/32 outline I. Introduction II. Organic Polymer solar cells • Junction type • Working principle • The layer stack III. Fabrication methods • Spin coating • Spray coating • Fabrication steps • specification IV.Discuss the article
  3. 3. Introduction 3/32 Organic solar cells (OSCs) have attracted strong attention in recent years • Clean • Renewable • Flexibility • Thinness • Simple Manufacturing Process
  4. 4. 4/32 Introduction Organic solar cell (OPV) 1. Dye sensitized 2. Polymer 3. Liquid crystal
  5. 5. 5/32 outline I. Introduction II. Organic Polymer solar cells • Junction type • Working principle • The layer stack III. Fabrication methods • Spin coating • Spray coating • Fabrication steps • specification IV.Discuss the article
  6. 6. 6/32 Organic Polymer solar cells Junction type o Single layer o Bilayer o Bulk Heterojunction o Graded Heterojunction o Continues Heterojunction
  7. 7. 7/32 Organic Polymer solar cells Working principle Heterojunction o A heterojunction is the contact of two materials with different electrical properties. o The donor is more electron rich than the acceptor.
  8. 8. Organic Polymer solar cells Working Principle Light absorption (exciton formation) 8/32
  9. 9. 9/32 Organic Polymer solar cells Working Principle Exciton diffusion
  10. 10. 10/32 Organic Polymer solar cells Working Principle Charge transfer
  11. 11. 11/32 Organic Polymer solar cells Working Principle Charge collection
  12. 12. Organic Polymer solar cells The layer stack 12/32  Active layer • Absorbs light • Consist of : donor + acceptor  Transport layers • based on materials which have the capability of being able to primarily transfer either electrons or holes • hole transport materials : (MoOx) • electron transport material: (LiF), (Ca) ,(ZnO) ,(TiO)
  13. 13. Organic Polymer solar cells The layer stack 13/32  Electrodes • Most common material: (ITO) due to a high optical transmission combined with a low resistance (a transmission of >85% at <10 Ohm/sq) • PEDOT:PSS (allow conductivities of more than 500 Scm with a transmission of >80%) easier fabrication on flexible substrates, better tolerance towards bending compared to an ITO electrode Substrates •Glass •plastics
  14. 14. 14/32 outline I. Introduction II. Organic Polymer solar cells • Junction type • Working principle • The layer stack III. Fabrication methods • Spin coating • Spray coating • Fabrication steps • specification IV.Discuss the article
  15. 15. Fabrication Methods Spin Coating 15/32 • The deciding process parameters involved in spin coating are: 1. Solution viscosity 2. Angular speed 3. Spin Time • Advantage: possibility of making very well defined film thicknesses • Disadvantage: difficulty with scaling to large area samples
  16. 16. Fabrication Methods Spray Coating 16/32 (Http://Www.Nanowerk.Com/Spotlight/Id17636.Jpg)
  17. 17. Fabrication Methods Spray Coating 17/32 Atomization process: 1. Surface tension viscosity 2. Fluid density 3. Gas flow properties 4. Nozzle design  Quality of the coated layer 1. Wetting behavior 2. Surface properties 3. Working distance 4. Coating speed 5. Droplet sizes 6. Amount of sprayed layers. The Surface roughness : spray ~tens of nanometers spin coated ~few nanometers.
  18. 18. Fabrication Methods ITO coating on glass substrate[7] 18/32 𝐼𝑛𝐶𝑙3and 𝑆𝑛𝐶𝑙2 powder Dilution with methanol Dissolution with glaciel acetic acid Mixing(25 ̊C,1h,air) Glass slide substrate rinsed in acetone dried in air The solutions were deposited on glass substrates by spin coating Drying (300 ̊C,5min) heat treatment(500 ̊C,5min) Annealing (600 ̊C,1 hr, air) ITO Film
  19. 19. Fabrication Methods ITO−coated glass substrates cleaning[8] 19/32 1. cleaned with detergent 2. ultrasonicated in acetone and isopropyl alcohol for 15 min 3. dried in an oven at 120 °C 4. UV–ozone was used to treat the ITO surface for 10 min
  20. 20. Fabrication Methods PEDOT:PSS layer formation[8] 20/32 PEDOT:PSS solution irradiated with UV light (emission centered at 365 nm and power density of 300 µW 𝑐𝑚−2) in a dark glove box for 15, 30, 45, or 60 min. sprayed (by handheld airbrush ,0.1 Mpa, distance 30cm,20s) spin-coated(5000 rpm ,30 s) Annealing (150 °C, hot plate ,10 min) The thickness of the PEDOT:PSS film was well controlled in the range of 30–40 nm
  21. 21. Fabrication Methods active layer formation (bulk heterojunction film )[8] 21/32 mixing in chlorobenzene solution different blend ratios(1:1; 1:1.5, 1:2, 1:3, and 1:4 (w/w)) sprayed (0.1 Mpa, distance 20 cm, 30 s) spin-coated(1500 rpm, 30 s) Polymer and PC70BM The thickness of active ~ 120 nm
  22. 22. Fabrication Methods AL Deposition[8] 22/32 The active surface area of the device was 0.12 cm2 . samples transferred into a vacuum chamber deposit Al (100 nm, pressure 2.0 * 10-6 Torr.)
  23. 23. Specification Spin coating Spray coating • Max Temperature: 150 ̊C • No need to clean room • Needs vacuum for AL dep • Thickness≅260nm • Weight: light weight • Material: no rare, not toxic • PCE=4.94% • Short life time • Can’t be used in R2R process • flexible • Max Temperature: 150 ̊C • No need to clean room • Need vacuum for AL dep • Thickness≅260nm • Weight: light weight • Material: no rare, not toxic • PCE=4.94% • Short life time • Can be used in R2R process • flexible 23/32
  24. 24. 24/32 outline I. Introduction II. Organic Polymer solar cells • Junction type • Working principle • The layer stack III. Fabrication methods • Spin coating • Spray coating • Fabrication steps • specification IV.Discuss the article
  25. 25. Discuss the article 25/32 • Open Circuit Voltage (𝑉𝑜𝑐) • Short Circuit Current (𝐼𝑆𝐶) • Fill Factor(FF) • Power Conversion Energy(PCE)
  26. 26. Discuss the article 26/32
  27. 27. 27/32 • UV irradiated PEDOT:PSS films were qualitatively similar to annealed films • The UV-irradiated solvent-modified PEDOT:PSS films have a high dipole moment. The PEDOT:PSS segments are evenly distributed throughout the entire thin film and this could effectively reduce light scattering • Enlargement of the PEDOT grains and the reduction in the density of pores improvement of conductivity by increasing the number of conducting pathways for carriers. Discuss the article UV irradiation time 15 min 30 min 45 min 60 min RMS roughness 1.33 nm 1.24 nm 1.20 nm 1.17 nm
  28. 28. Discuss the article 28/32 • Low performance + Low life time need a solution! Nanoparticle The size of metal nanoparticles is one of key factors to strong light trapping
  29. 29. Discuss the article nanoparticle[9] 29/32 0.5 ml PEDOT:PSS solution+ 0.1 mg ZnO powder (size of nanoparticles smaller than 100 nm) LiF thin layer deposited by thermal vacuum evaporation ultrasonicated (2 hours and 30 minutes, room temperature) spin-coating
  30. 30. Discuss the article 30/32
  31. 31. Discuss the article 31/32 life time decreased due to: • The diffusion of PCBM molecules between the P3HT chains leading to a low crystalinity
  32. 32. 32/32
  33. 33. References [1] http://energy.dtu.dk/ [2] http://plasticphotovoltaics.org/lc/lc-solarcells.html / [3] https://en.wikipedia.org/wiki/Organic_solar_cell [4] http://depts.washington.edu/cmditr/modules/opv/index.html [5] http://edu.nano.ir/paper/68 [6] V.Doojin,” Fabrication of organic bulk heterojunction solar cells by a spray deposition method for low-cost power generation”, Appl. Phys. Lett,vol.91,Aug,2007. [7] E. Celik,U. Aybarc,” ITO films on glass substrate by sol–gel technique: synthesis, characterization and optical properties”, JSST,vol.50,pp.337-347,June,2009. [8] P.Kumar,” Comparison of properties of polymer organic solar cells prepared using highly conductive modified PEDOT:PSS films by spin- and spray-coating methods”, JJAP, vol.53,no.1s, Dec,2013. [9] A. Radu,” The Influence of LiF layer and ZnO nanoparticles adding on the performances of flexible photovoltaic cells based on polymer blends”, DIG J NANOMATER BIOS,Vol. 6,no.3, pp.1141-1148, Sep, 2011.

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