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DSSC and TF Poly-Si Solar Cells

Dye-sensitized TiO 2 and thin film poly-silicon solar cells: fabrication and measurements of photo n-to-electron conversion efficiencies using LabView. DSSC and TF Poly-Si Solar Cells. National Nano Device Laboratory Tainan Science Park. Taiwan Tech Trek (TTT) 2006 Interns: Eric Chang

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DSSC and TF Poly-Si Solar Cells

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  1. Dye-sensitized TiO2 and thin film poly-silicon solar cells: fabrication and measurements of photon-to-electron conversion efficiencies using LabView DSSC and TF Poly-Si Solar Cells

  2. National Nano Device Laboratory Tainan Science Park Taiwan Tech Trek (TTT) 2006 Interns: Eric Chang Department of Electrical Engineering and Computer Sciences University of California at Berkeley Kevin Chen Ying Chang Department of Electrical and Computer Engineering University of California at San Diego Yu-Kai (Kevin) Su Department of Biomedical Engineering Washington University in St. Louis

  3. The Clean Room Different levels - NDL Tainan is level 10,000 per cubic feet Requires standard uniforms For our clean room, we have to have specialized hats, gloves, jackets, shoes, and mouth covers Temperature, pressure, and humidity are constantly monitored so room condition can be kept at an optimal level Standard Lab Clothing

  4. The Equipments and Technology • Wet bench • Consists of four different chemical solutions to eliminate extra foreign particles • PECVD (Plasma Enhanced) - produces organic thin film by growing silicon dioxide/poly-silicon • Furnace is LPCVD (Low Pressure) – same function as PECVD requiring longer time for processing but better quality Wet Bench

  5. Photolithography Includes following processes in order: priming, putting on photo resist (PR), pre-baking, UV exposure with mask, and then hard bake Exposure - uses a mask to allow entrance of UV light to hit target wafer, which causes chemical reaction with the PR Area uses yellow light so PR is not damaged The Equipments and Technology (Continued) Photolithography

  6. PR spin coated onto wafer (manually or automatically) Track (automatic) – Can perform all steps necessary for coating the wafer using an automated computer system Spin Coater (manual) Choose desired size of target Manually test optimal parameters (RPM/time/position) The Equipments and Technology (Continued) Spin Coater

  7. Spin Coating Main purpose: to achieve an even surface

  8. Side View of an Uneven Surface slide Uneven

  9. Side View of an Even Surface slide Smooth

  10. Spin Coating Demonstration

  11. Thermal Evaporator and Sputter - both coat thin film of metal on the target wafer Thermal evaporator – evaporated metal on bottom hits wafer on top, then molten metal gradually spreads evenly from center of wafer to coat surface Sputter – molten metal on top rains down droplets at numerous positions to coat the wafer on the bottom The Equipments and Technology (Continued) Sputter

  12. The ICP and RIE are both machines that are used for etching ICP is better since it can etch out the whole target wafer while the RIE cannot Etchant is very corrosive and dangerous, so protective gear is required The Equipments and Technology (Continued) Protective Mask

  13. AFM – scans out 3D image of target’s surface Nano-scale probe vibrates with a certain frequency at a synchronized distance away from the target Vibration changes can be detected by a light that is reflected upon it, which gives data for image Probe station Uses microscope and nano-scale probe to make contact with different shapes of arrays on target Probe station is utilized for contact with conductive materials, while AFM targets regular surfaces The Equipments and Technology (Continued)

  14. The Mask The design and pattern of the mask - developed through AutoCad, then sent to specific company for production Normal mask is created with glass and Chromium (1-2 months for completion) Due to limited time, replaced the materials with plastic and chalk, (only an overnight process) Masks

  15. Mask Aligning UV

  16. Some Measuring Equipments

  17. Some Measuring Equipments

  18. Finding the Optimal RPM and Time 1 2 3 4 RPM 500 1300 1200 1100 Time (second) 20 30 30 30 0.2 mL HAc (hydrogen acetate) in 100 mL DI water TiO2: 1.35±0.05 g with 40 drops of acetic acid

  19. RPM Time (second) Comment 7A 1100 30 7B 1100 30 More drops at corners 7C 1000 30 7D 900 30 not drops, painted on (corners) 7E 900 30 Less TiO2 at the corners compared to D 7F 1100 30 Less drops, not as evenly distributed 7G 1100 30 7H 1100 30 Table 1: 70 Drops of Acetic Acid

  20. RPM Time (second) Comment 8A 1000 30 8B 900 30 Not evenly spread 8C 700 20 8D 800 10 8E 700 40 Table 2: 80 Drops of Acetic Acid

  21. Triton X 100 Surfactant

  22. RPM Time (second) Comment 7XA 900 30 Good, with little bubbles 6XA 1100 30 Thicker than 7A, more bubbles 6XB 1200 30 7XB 900 30 7XC 800 30 8VC 700 30 Surfactant Table 3: 2 g TIO2  {60, 70, 80} drops  Triton X 100 (surfactant)

  23. Fabrication of DSSC Upper Electrode (1) Spin-coating PR: AZ 5214 Step 1: 500 RPM for 5 s Step 2: 3000 RPM for 30 s Soft bake 90°C, 30 s Exposure Plastic mask of our design Duration: 4 s

  24. Fabrication of DSSC Upper Electrode (2) Reverse Bake 110°C, 120 s Reverse, flood Exposure (without mask) 15 s Develop AZ 300 developer for about 30 s Hard Bake 100°C, 60 s

  25. In order to make the photoresist negative: REVERSE BAKE AND REVERSE FLOOD EXPOSURE

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