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DSSC- Dye Sensitized Solar Cells

 

Dye-sensitized solar cells (DSCs) [1] are typically fabricated on transparent conducting glass substrates and comprise a 10 micron-thick, high-surface-area porous layer of TiO2 nanoparticles, a dye monolayer anchored to the TiO2 which absorbs sunlight, an electrolyte which transports charges and a catalytic layer that enables passage of charge from one of the contacts (i.e. the counter-electrode) to the ions in the electrolyte [2]. All these layers can be deposited in solution or via pastes (e.g. screen printing) requiring low cost deposition equipment [3]. Record efficiencies are around 13% over small laboratory cells [4] and 8% over small modules [5-6] under standard test conditions.

A great variety of dyes have bene employed as sensitizers, including organometallic (e.g. N719) and metal-free organic dyes. After the first decade, where organometallic dyes have shown best perfomances, now DSSC record efficiencies approaching 15% have been obtained by using metal-free organic dyes, in some cases in combination with Co-based complexes,[7] which combine higher perfomances with greater variety of properties and much lower synthesis costs.[7-8]

DSCs have demonstrated remarkable power outputs under low level indoor lighting [9-10]. In fact, because of this, and because lifetimes for many indoor applications can be met, industrial outfits such as G24 Power have commercialized DSCs in their flexible form [11] on metal foils (but they can also be developed on plastic films) mainly for these environments.

DSC have attracted a lot interest because they enable to make semi-transparent coloured glass facades desirable for BIPV applications which is potentially a huge market [12-13]. The efficiency, colour and transparency parameters can be tuned depending on applications and they work very well even under indirect light. More R&D is required for attaining a product that is able to consistently guarantee outdoor stability of two decades required for commercialization with a high enough efficiency. Stability can be improved by working on all constituent materials, especially the electrolyte (e.g. quasi solid, or solid mediators) [14-16] although, at the moment, often compromising on the levels of efficiency. Thus, there is room for optimizing the combined efficiency/lifetime parameters for long term outdoor operation.

Published by Thomas Brown, (UTV)
Alessandro Abbotto (UNIMIB), Aldo Di Carlo (UTV)

 

References:

  1. B. O’Regan and M. Grätzel, Nature, 353, 737-740 (1991)
  2. A. Hagfeldt et al., Chem. Rev., 110, 6595–6663 (2010)
  3. P. Mariani et al., Semiconductor Science and Technology, 30, 104003, (2015)
  4. S. Mathew et al. Nat Chem. 6, 242-7 (2014)
  5. Han et al., Appl. Phys. Lett. 94, 013305 (2009)
  6. H. Arakawa et al, Current Applied Physics, 10, S157–S160 (2010)
  7. Kakiage, Y. Aoyama, T. Yano, K. Oya, J.-i. Fujisawa and M. Hanaya, Chem. Commun., 51, 15894-15897 (2015).
  8. Yao, M. Zhang, H. Wu, L. Yang, R. Li and P. Wang, J. Am. Chem. Soc., 137, 3799 (2015)
  9. De Rossi et al., Applied Energy, 156, 413–422, (2015)
  10. Ricoh <http://www.ricoh.com/about/company/technology/tech/066_dssc.html> (2014).
  11. T.M. Brown et al, J. Chem. A, 2, 10788-10817 (2014)
  12. A. Hinsch et al., ChemPhysChem, 15, 1076–1087 (2014)
  13. A. Fakharuddin et al., Energy Environ Sci, 7, 3952–3981 (2014)
  14. U. Bach et al., Nature 395, 583-585 (1998)
  15. P. Wang et al., Nature Materials 2, 402-407 (2003)
  16. H. Snaith et al, Adv. Mat., 19, 3187–3200 (2007