1. Titanium Dioxide Self-ordered
Arrays for use in DSSC
Photovoltaics
By: Anna
Dorfi
June-August
2012

2. Objectives:
• Achieve TiO2 pore sizes of 100-150 nm
• Use Scanning Electron Microscope for characterization (SEM)
• Length of 4-20 μm
• 3-6 μm has been achieved, membrane stays on template and is
stable
• Increase surface area inside the nano-tubes.
• “Bamboo” procedure of varying voltage
• Fill pores with P25 TiO2
• Use Ruthenium and test solar cell efficiency

3. Start:
• Anodizations at 25C with .38 wt% NH4F and 1.8wt% H20 and
50 V.
• 40-60 nm size pores, +4-5 nm
-2
0
2
4
6
8
10
12
14
0 1000 2000 3000 4000 5000 6000 7000
Current(mA)
Time (every 2 s)
Current vs. Time - AD008 (50V) Anodization 1

4. Developments
• Higher Voltages
• Bigger Pores
AD011 (70V)
Average pore size: 68.0 nm
AD009 (60V)
Average pore size: 49.0 nm

5. AD015 (80V):
Average pore size: 58.54 nm
AD017 (85V):
Average pore size: 81.34 nm
- Higher voltages seem to produce less of an ordered pore array

6. • Varying Voltage to create “bamboo” tubes with higher surface
area.
• Nanotube ridges
ridges
AD022 (75V 4min, 20V 2 min):
Average pore size: 79.92 nm

7. AD008 (50V 4 min, 10 V 2 min), 10 cycles:
Average pore size: 59.8 nm
ridges

8. -5
0
5
10
15
20
25
30
35
40
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Current(mA)
Time (every 2s)
Current vs. Time -AD018 (60V), 2nd Anodization
Average pore size: 82.65 nm
ridges
AD018 (60 V 2min, 10V 4 min for 10 cycles @ 24°C):

9. • Higher NH4F wt% in anodization solution
• Bigger Pores
• Less ordered array
AD020 (75V and 20 V, .38wt% NH4F
and 1.8wt% H20):
Average pore size: 66.68 nm
AD022 (75V and 20 V, .42wt% NH4F
and 1.9wt% H20):
Average pore size: 79.92 nm

10. TiO2 Nanoparticle Filling
• The AD028 samples using the P25 had partially filled
pores. The TiCl4 method will not be utilized in the future.
• Variations on the procedure using P25 powder will be
used in the proceeding methods for filling.
• 2 samples from AD049 will be put in the USB with the prepared
solution before being put in the autoclave.
• Older samples with 110 nm pores will be reproduced for
future use.

11. Nanoparticle Procedures:
• Each foil is put in a vacuum at 400C for 1.5-2 hours to become crystalline.
The sample is then cut in 4 pieces for use in different coating methods.
TiCl4 Method:
• Two syringes of TiCl4 and some chloroform are put in a vacuumed flask
with the samples and stirred for 15 minutes.
P25 Method:
• The solution of P25 particles was made with 100 ml of distilled water and
.015 M nanoparticle powder (calculated to be .12g P25 powder).
• Using ultra-sonicating and magnetic force the solution was stirred for
about 15 minutes at room temperature. The 30 ml of this solution is used
for each sample.
• It is sealed and put in an autoclave at 85°C for 8 to 12 hours for coating.
• The PCTs are finally achieves after the reactants are cooled freely and
washed with water, then heated at 400C for 2 hours.

12. AD028 – TiCl4 Method:
AD028_ TiCl4_1 AD028_ TiCl4_2

13. AD028 – P25 Powder Method:
AD028_ P25_1 AD028_ P25_2

14. AD028 P25 Sample 2:

15. Future Work
• Vary the electrolyte solution used along with the voltages
and temperatures to get membranes with even bigger
pores.
• Continue to reproduce Samples AD028 and AD032 for
continued use in later steps
• Continue developing different procedures for filling the
pores with P25 TiO2 nanoparticles.
• Dye the samples with Ruthenium dye and test their
efficiency!

16. Thank you!!
I would like to acknowledge Patrick Leidich and
Prof. Dr, Tremel for their guidance and the DAAD
RISE program for the research opportunity.