1. Nanocellulose In Dye Solar Cells
Katariina Solin
Supevisors: Kati Miettunen, Maryam Borghei

2. Motivation
The spatial variation of electrolyte components in conventional DSC
The sealing of the cell with liquid electrolyte
No leakage
Solar Power Breakthrough: New Inexpensive, Environmentally Friendly Solar Cell | PlanetSave

3. Dye-sensitized Solar Cells (DSC)
Thin film solar cells
Photoelectrochemical system
Semiconductor between photo-sensitized anode and electrolyte
Porous layer of TiO 2 nanoparticles + molecular dye (anode)
Platinum based catalyst (cathode)
When placed in the sun, photons of the sunlight can excite electrons on the p-type side of the semiconductor, a process known as photoexcitation. In silicon, sunlight can provide enough energy to push an electron out of the lower-energy valence band into the higher-energy conduction band. As the name implies, electrons in the conduction band are free to move about the silicon. When a load is placed across the cell as a whole, these electrons will flow out of the p-type side into the n-type side, lose energy while moving through the external circuit, and then flow back into the p-type material where they can once again re-combine with the valence-band hole they left behind. In this way, sunlight creates an electric current.(

4. Dye-sensitized Solar Cells (DSC)
Sunlight creates an electric current:
Sunlight passes through the transparent electrode into the dye layer → excite electrons that flow into the TiO 2 → diffusion
Flowing through the external circuit → electrons are re-introduced into the cell on a metal electrode
Electron flow into the electrolyte
The electrolyte transports the electrons back to the dye molecules
When placed in the sun, photons of the sunlight can excite electrons on the p-type side of the semiconductor, a process known as photoexcitation. In silicon, sunlight can provide enough energy to push an electron out of the lower-energy valence band into the higher-energy conduction band. As the name implies, electrons in the conduction band are free to move about the silicon. When a load is placed across the cell as a whole, these electrons will flow out of the p-type side into the n-type side, lose energy while moving through the external circuit, and then flow back into the p-type material where they can once again re-combine with the valence-band hole they left behind. In this way, sunlight creates an electric current.(
National Institute for Materials Science (NIMS) |

5. Nanocellulose Bacterial cellulose films and electrospun fibers
Derived from abundant and renewable resources, non-toxic
Thin films
Highly porous
Absorbing sponge

6. Solar Cells with Nanocellulose
Method to deposite electrolyte in DSC
Nanocellulose absorbs the electrolyte
No electrolyte pumping needed → no uneven distribution of electrolyte components
Molecular filtering effect
No filling holes → simplifies the sealing of the cell
Miettunen, K. et. al. Nanocellulose aerogel membranes for optimal electrolyte filling in dye solar cells. Nano Energy Vol. 8. pp

7. Solar Cells with Nanocellulose
Bacterial cellulose films and electrospun nanocellulose
Cell assembly
Miettunen, K. et. al. Nanocellulose aerogel membranes for optimal electrolyte filling in dye solar cells. Nano Energy Vol. 8. pp

8. References
Miettunen, K.; Vapaavuori, J.; Tiihonen, A.; Poskela, A.; Lahtinen, P.; Halme, J.; Lund, P. Nanocellulose aerogel membranes for optimal electrolyte filling in dye solar cells. Nano Energy Vol. 8. pp
Miettunen, K.; Halme, J.; Lund, P. Spatial distribution and decrease of dye solar cell performance induced eletrolyte filling. Electrochemistry Communications Vol. 11. pp
Miettunen, K.; Asghar, I.; Mastroianni, S.; Halme, J.; Barnes, P.R.F.; Rikkinen, E.; O'Regan, B.C.; Lund, P. Effect of molecular filtering and electrolyte composition on the spatial variation in performance of dye solar cells. Journal of electroanalytical chemistry Vol pp
Miettunen, K.; Barnes, P.R.F.; Li, X.; Law, C.H.; O Regan, B.C. The effect of electrolyte filling method on the performance of dye sensitized solar cells. Journal of Electroanalytical Chemistry Vol pp
Hashmi, G.; Miettunen, K.; Peltola, T.; Halme, J.; Asghar, I.; Aitola, K.; Toivola, M.; Lund, P. Review of materials and manufacturing options for large area flexible dye solar cells. Renewable & Sustainable Energy Reviews, Vol. 15, nro 8, pp
O’Regan, B.; Grätzel, M.; A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature, Vol 353, pp